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THE

RAY SOCIETY

INSTITUTED MDCCCXLIV

Thi* volume is issued to tlie Subscribers to the RAY SOCIETY for

the Year 1922.

LONDON

MCMXXIII

A MONOGRAPH

OF THE

BRITISH DESMIDIACE.E

.

BY

THE LATE

W. WEST, F.L.S., ^L

Lecturer in Botany, Biology, and Bacteriology at the Technical

College, Bradford;
Ex-president of the Yorkshire Naturalists' Union;

AND

THE LATE

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 ,//«.? Hutchinson Research Student of St. John's

College, Cambridge

VOLUME Y

BY

NELLIE CARTER, D.Sc.,

Research Assistant at the Missouri Botanical Garden; Formerly Research
Assistant at the University of Birmingham ; and Seessel Research

Fellou- at Yale Unirersiti/.

LONDON
PRINTED FOR THE RAY SOCIETY

1923

PRINTED BY

ADLARD AND SON AND WEST NEWMAN, LTD.,
LONDON AND DORKING.

PREFACE TO VOL. Y

ELEVEN years have elapsed since the appearance of
the fourth volume of this series, a period which has seen
many changes, and during which the science of Algology
has lost a number of its most active investigators.

o

Undoubtedly the worst blow, as far as Britain is con-
cerned, has been the irreparable loss of the two authors
of the British Desmidiacece. In the death of his father,
William West, in 1913, George S. West suffered the
bereavement not only of a parent to whom he was
devoted but also of a colleague who had been a fellow-
worker and supporter since his early childhood when
they pursued their algological studies together. From
this blow he never quite recovered, for continued ill-
health and the strenuous years of the Great War played
havoc with his constitution, and finally, in 1919, he
succumbed to pneumonia.

In attempting to complete, at the request of the Ray
Society, this great work of her beloved and much-
respected teacher, the writer is aware that she has
undertaken a difficult task ; yet she feels that, if only
in publishing and thus rendering available for students
of algse the remainder of Professor West's beautiful
drawings of Desmids, she will have accomplished some-
thing useful. Wherever possible the figures given have
been copied from Professor West's drawings. Failing
this, the drawings were made by the present writer in

VI PREFACE.

most cases from material identified by Professor West ;
these are distinguished in the description of the plates
by an asterisk. As a last resource the figures of previous
authors have been copied.

Professor West's drawings and a list of British and
foreign localities for Desmids were the only material
left by the Wests on which the remainder of the work
could be based. For inaccuracies in the diagnoses or
remarks the writer must take entire responsibility.
Whilst she has attempted to embody in these remarks
all that has been previously published concerning the
various species and, in addition, has sometimes included
her own original observations, she can only regret that
the information she is able to give is so meagre and
incomplete in comparison with what it might have been if
Dr. West had not prematurely died ; for it is impossible
that work resulting from a six or eight years' know-
ledge should form a worthy conclusion to that started
on the basis of a life-long study.

Undoubtedly, many students when studying the
numerous species of the difficult genus Staurastrum, will
be especially disappointed at being deprived of the experi-
ence of our two great algologists. The arrangement into
the main sections E, F, G, etc., adopted by the writer
is, on the whole, the provisional one prepared by the
Wests for the classification of the species of this genus
and outlined by them in Vol. IV. A few alterations
were made when the writer could not reconcile the
structure of the species concerned with the characters of
the group. These include the removal of St. pungens
and St. Simonyi from Section E to Section F, St.
forficulatum from Section I to Section J, and St.
aciculiferum from Section J to Section I. The writer
realises that the arrangement of the species within each

PREFACE. Vll

group is very unsatisfactory and that, when unusual
forms of some species are in question, the keys will be
useless ; but she feels quite unable to make any improve-
ment in these respects.

The localities of species, as given in the text, were
compiled in the main by the two Wests, but a number
of others have been added by the author from recent
papers. The Canadian records were obtained from a
hitherto unpublished list kindly sent by Mr. C. W. Lowe.

To the Department of Scientific and Industrial
Research at London the writer is indebted for a grant
which enabled her to spend an uninterrupted year at
the work, and she is also indebted to Dr. G. T. Moore
who allowed her to complete it during the tenure of a
Fellowship at the Missouri Botanical Garden. To
Professor Yapp, Dr. Jessie S. Bayliss-Elliott, and others
in the University of Birmingham, and to all those who
by their constant encouragement and interest have
stimulated the continuation of the work, the writer is
very grateful, and hereby expresses her warmest thanks.

NELLIE CARTER.

The Missouri Botanical Garden ;
August, 1922.

CONTEXTS OF VOL. V.

ADDITIONAL BIBLIOGRAPHY ....
FAMILY DESMIDIACE^:.

SUB-FAMILY II. PLACODERM^E.

TRIBE 5. COSMARIE^E.

GENUS 18. STAURASTRUM (concluded)

19. COSMOCLADIUM

20. OOCARDIUM

21. SPH^EROZOSMA

22. ONYCHONEMA

23. SPONDYLOSIUM

24. HYALOTHECA

25. DESMIDIUM .

26. GYMNOZYGA

PAGE
xvii

ADDENDA
INDEX

33

S3

33

33

33

33

33

1

. 197

. 203

. 206

. 215

. 219

. 228

. 240

. 254

. 258
271

/ <\

LIST OF THE PLATES.

PLATE CXXIX.

Figs. 1. — Staurastrum

fn in (vol. iv, p. 176)
2-5.— St. (flab nun (p. 2)
,, 6-8. — St. apiculatnni (p. 6)

9-13.— Sf. dejcrfnni (p. 7)
„ 14-16.— St. Dickiei (p. 3)

PLATE CXXX.

Figs. 1-5. — Staurastrum dejectum

r (P- 7)
,, 6-9. — St. coiDHitHiH (]>. 15)

10-14. — St. >nucroii'(f>/iii (p.

,,

„

15-16. — St. curvattun (p. 19)
17-18. — St.jaculiferum(p. 16)

PLATE CXXXI.

Figs. 1-6. — Staurastrum

f era in (p. 16)

„ 7-10. — St. megacanthum (p.
20)

PLATE CXXXII.

Figs. 1-4. — Staurastrum pfcro-

sporum (p. 14)
5-9.— St. O'Mearii (p. 13)
10-12.— St. arixtifenuH (p. 22)
13-12.— St. cuspidatum (p. 23)
20. — St. leptodenuuin (p.
27)

55

55

Figs.

J5

55
55

55
55

55
55

Figs.

55
55

55

55

PLATE (.'XXXIII.

1. — Staurastrum ruspi-

tl (if inn (p. 23)

2-3. — St. pscudocitxp id at u »t
(p. 26)

4. St. ttltH/'txciUilUH (p.

28)

o.—St. U»(/eri (p. 28)
6-7. — St. subcruciatum (p.

42)

8-12.— St. Aricula (p. 40)
13-15. — St. denticulatum (p.

38)

16. — St. corn u/ nni (p. 31)
17-22.— St. Inna1iun (p. 29)

PLATE CXXXIV.

1-3. — Staurastrum loinji-

spinum (p. 33)
4:.—St.bifidum(p.32)
5 — St. quadrangulare (p.

37)

Figs.

55

55

6. — St. aciculiferum (p.

171)
7. — St. spiniferum (p. 50)

PLATE CXXXV.

1-4. — Staurastrum Simonyi

(p. 45)
5-7. — St. quadrispinatum

(p. 38)

8-10. — St. punijcnx (p. 44)
11-13.— St. Bi-axilicnse (p. 35)
14-15.— St. Gat »«'»«> (p. 32)

Xll

LIST OF THE PLATES.

Figs.

55

55

Figs.

55

Figs.

55
5>

Figs.

5?

5 1
• ?
•••>

PLATE CXXXVI.

1 . — Staurastrum Hystrix

(p. 60)

2-7. —St. teliferum (p. 58)
S-ll.—St. polytrichum (p. 53)
12. — St. erostellum (p. 72)
13-14. — St. setigerum (p. 52)

PLATE CXXXVII.

1 -3 . — Staurastrum gladio -

sum (p. 57)
4-6. — St. Brebissonii (p.

61)

7. — St. Saxonicum (p. 54)
8. — St. Picum (p. 51)
9-11. — St. erasum (p. 71)

12. — St. echinatum (p. 56)
13-15. — St. cumbricum (p. 55)

PLATE CXXXVIII.

1 -3 . —Staurastrum pilosum

(p. 63)

4-6.— St. hirsutum (p. 65)
7-8.— St. Ravenelii (p. 70)

9.— St. muricatum (p. 67)
1U-13. — >SY. pyramidatum (p.
68)

PLATE CXXXIX.

1-2. — Staurastrum m uri-

catum (p. 67)
3. — /5Y. trachygonum (p.

50)
4. — *S7. horametrum (p.

51)

5. — St. cristatum (p. 47)
6-7. — St. oligacanthum (p.

48) "
8-9. — /S7. echinodermum (p.

79)

10. — >S7. )n(ianiense (p. 75)
11-15.— ^SV. Arnellii (]}. 79)
16. — />7. pyramidatum (p.
68)

Figs.

5J

PLATE CXL.

1-2. — Staurastrum scabrum

(p. 81)

3-5. — St. subscabrum (p. 82)
6-10.— £7. acarides (p. 73)
11-13. — >57. asperum (p. 74)
14-16. — &7. spongiosum (p. 76)

PLATE CXLI.

Figs. 1-3. — Staurastrum Iceve (p.

92)
,, 4-8. — St. inconspicuum (p.

86)

-St. bacillare (p. 84)
-St. brachiatum (p. 88)
16. — St. nodosum (p. 88)
17-18. — St. lcBvispinum(p. 90)
1 9 . — St . s ublcevispinwn

(p. 91)
20. — St. subnudibrachiatum

(p. 91)
21. — St. asperum (p. 74)

„ 9-13.
14-15.

Figs.

53

•
55

55

Figs.

PLATE CXLII.

1 -7 . — Staurastrum brachia-

tum (p. 88)
8. — St. inconspicuum (p.

86)
9-10. — St. franconicum (p.

85)

11-15. — St. hexacerum (p. 138)
16-18. — St. neglectum (p. Ill)
19-20. — St. Haaboeliense (p.

140)
21-22. — St. brachycerum (p.

136)

23.— St. affine (p. 128)
"24:.— St. polymorphism (p.
125) '

PLATE CXLIII.
1-6.

55

pulytnor-
p/non (p. 125)
7-8.— /SY. injicxiim (p. 108)

LIST OF THE PLATES.

Xlll

PLATE CXLIII — continued.

Figs. 9-13. — St. crenulatum (p. 1 10)
,, 14-16. — St. proboscidiioit (p.

129)

17.— St. bicorne (p. 117)
,, 18-22. — St. oxyacantham (p.

169)
23. — St. eboracense (p. 137)

Figs.

,,

PLATE CXLIV.

1-2. — Staurastrum stib-

gracillimum (p. 118)
3-13. — St. gracile (p. 96)

PLATE CXLV.

Figs. 1-10. — Staurastrum

doxutti (p. 101)

,, 11-12. — St. pseudopelagictim
(p. 107)

PLATE CXLVI.

Figs. 1-3. — Staurastrum para-

doxwn (p.
,, 4. — St. dubiuni (p.

5.— St. boreale (p. 112)
6. — St. pelagicum (p. 124)
7-8. — St. anatinum (p. 142)

PLATE CXLVII.

Figs. 1-6. — Staurastrum ana-

I in ton (p. 142)
,, 7. — St. natator (p. 149)

PLATE CXLV1II.

Figs. 1. — Staurastrum Dun-

cense (p. 116)

'2-3.— St. Manfeldtii (p. 114)
,, 4. — St. dorsidentiferum

(p. 171)
b-7.—St. Sebaldi (p. 166)

5J

55

Figs.

55
JJ

55

J5

5)

Figs.

Figs.

55
55

Figs.

PLATE CXLIX.

1 . — Staurastr uin iotan ton.

(p. 121)

2-5.— St. tetracerwm (p. 118)
6.— St. micron (p. 123)
7. — St. irregular e (p. 150)
8. — St. latiusculum (p.

124)

9-10. — St.cyrtocerum (p. 135)
1 1 . — St. pseudotetracerum

(p. 122)

12.— St. Chavesii (p. 134)
13. — St. Pseudosebaldi (p.

113)
14-16. — St. Heimerlianum

(p. 165)
11.— St. Sebaldi (p. 166)

PLATE CL.

1-3. — Staurastrum Arachne

(p. 151)

4. — St. cyrtocerton (p. 135)
5-13. — St. margaritaceum (p.

131)
14-15. — -St. sexcostatnnt (p.

147)
16.— SZ. Cerastes (p. 141)

PLATE CLI.

1 . — Staurastrum Cerastes

(p. 141)

2-5. — St. elongatum (p. 156)
6. — St. barbaricum (p. 157)
7-8. — St. verticillatum (p.

155)
9-11.— St. vestituiH (p. 158)

PLATE CLII.

1 -4 . — Staurastrum Oph i u ra

(p. 153)
5-8. — St. vestitum (p. 158)

XIV

LIST OF THE PLATES.

5)
55

PLATE CLIII.

Figs. 1-4. — Staurastrum aculca-

tum (p. 160)
5. — St. vest-Hum (p. 158)
6-7— S*. Archer ii (p. 155)

PLATE CL1V.

Figs. 1-4. — Staurastrtim cond'o-
vcrxiun (p. 162)

\ L '

„ 5-7.— St. cosmospinosum

(p. 164) J
8-12. — St. 'monticulosum (p.

183)
,, 13. — St. megalonotum (p.

182)
„ 14-16.— St. forjwidatum (p.

187)

PLATE CLV.

Figs. 1-7. — Staurastrum furcatum

(p. 173)

8, $.—St. arcuatum (p. 180)
10. — St. subavicula (p. 181)
11. — St. ainphidoxon (p.

181)
., 12-14. — St. Tohopekaligense

(P-

Figs.

Figs.

55

PLATE CLVI.

1 -2 . — Staurastrum d ipla-
canthuin (p. 186)
3. — St. senarium (p. 175)
4.— St. West ii (p. 187)
5. — St. gemeltiparum (p.

176)

6.— &. Clevei (p. 177)
l-ll.—St.furciyerum (p. 188)

PLATE CLVII.

1.- — Staurastrum ftirci-

1/cnun (p. 188)
2-4. — St. sexangulare (}>.

L94)
5.— St. Arctiscon (p. 193)

PLATE CLVIII.
Fi«rs. 1-3. — Cosmocladium con-

o

strictum (p. 198)

4-7.— C. prrisNtun (p. 200)

8-10.— C. pusillnm (p. 201)

„ 11-12.— C. pidclclhnn (p. 200)

13-16.— C. Saxonicum (p. 202)

PLATE CLIX.

Figs. 1-8. — Oocardium stratum

(p. 204)
,, 9-12. — Spharozosm-a verte-

bra-tain- (p. 209)
13-17. — 8. Aubertianum (p.
207)

„

PLATE CLX.

Figs. 1-5

55
55
55

55

J5
55

55

Figs.

55

55

J5

55

-Sphcerozosma exca-

vatum (]). 211)
6-8. — S. granulatHin (p. 213)
9-II.—S. Wallichii (p. 214)
12. — S. vertebratum (p.

209)
13-14. — Onychonema jiliforme

(p. 216)

15-17. — 0. Iceve (p. 218)
18-22 . — Spondylosium pyy-

mceum (p. 220) '
23-25.— S. plan am (p. 222)

PLATE CLXI.

1-5. — Spondylosium pid-

chellum (p. 227)
6-7. — S. papillosum (p.

223)

8-11.— S. secede ns (p. 225)
12-14. — S. tetragon-urn (p.

226)

15.— S. eHipliciDH (p. 222)
1 6-27 . — Hyalotheca dissiliens
(p. 229)

LIST OF THE PLATES.

XV

PLATE CLXII.

Figs. 1-5. — Hyalotheca mucosa

(p. 235)
6-9.— #. undulata (p. 239)

W.—H. Imlica (p. 237)
„ 11-15.— #. neglectn (p. 238)
„ 16-19.— #. dixsiliens (p. 229)

PLATE CLXIII.

Figs. 1-4. — Hyalotheca neglecta

(p. 238)

,, 5-10. — DesniiiiiiDii Sira /'/://
(p. 246)

PLATE CLXIV.

Figs. 1-6. — Desmidium Apto-

gotiuni (p. 242)

„ 7-10.— D.cylim!n'rum(p. 249)
., 11. — D. occidentals (p. 245)

Figs.

55
55

PLATE CLXV.

1-4. — De*in iiliiuii coarcta-

tuw (p. 252)
5-6. — D. pseudostreptonema

(p. 244)

7.— D. Swartzii (p. 246)
8-10. — Gymnozyga monili-
f or mis (p. 255)

Figs.

55

Figs.

J5
55

55
55

PLATE CLXVI.

1 . — Staurastru m C haves i i

(p. 134)
2. — St. brevispinum (p.

269)
3. — Euastrum laticolle (p.

264)
4. — Staurastrum Pseudo-

sebaldi (p. 113)
5. — Desmidium, gracileps

(p. 252)

6-7. — D. quadrat um (p. 254)
8-9. — Closterium tumid um

(p. 263)
1 0. — Gymnozyga )ii,on ///-

for mis (p. 255)
11-13. — Roy a anglica (p. 2 ">'.•)
14. — R. cambrica (p. 260)

PLATE CLXVII.

1-4. — Oocardium ^ti-atmn

(p. 204)
5. — Euastrum mvnfrtiium

(p. 265)

6. — Roya obtusa (p. 260)
7. — ? Staurasti um iti-
jlexum (p. 108)
8-9.— St. Meriani (p. 269)
10. — Spondylosium Lun-

dellii (p. 224)
1 1 . — Micrasterias papilli-
fera (p. 266)

ADDITIONAL BIBLIOGRAPHY.

(SEE VOL. I, pp. xvii-xxxvi ; VOL. II. p. x : VOL. III. pp. xiii-

xv ; VOL. IV, pp. xi-xiv.)

ACTON, Hyalotheca dissiliens. — E. Acton, Studies on Nuclear
Division in Desmids I. Ann. Bot. xxx, 1916, p. 379.

ADAMS, Synops. Irish Alg. — -J. Adams, A Synopsis of Irish Alga?.
Trans. Koy. Irish Acad. xxvn, Sect. B, no. 2, 1908.

AGARDH, Syst. Alg. — A. C. Agardh, Systema Algarum. Lunda3,
1824.

ARCH in Joum. Bot. 1874. W. Archer.

ARCH, in Ann. Mag. Nat. Hist. ser. 5, vm, 1881. W. Archer.

BAILEY, Amer. Bacill. — J. W. Bailey, American Bacillaria. Part
I : Desmidiaceae. Amer. Journ. Science Arts, iv, 1, 1841.

BORGE, Botan. Notiser. — 0. Borge, Beitriige zur Algenflora von
Schweden. Botan. Not. 1913.

BORGE, Sao Paulo Alg. — 0. Borge, Die von Dr. Lofgren in Sao
Paulo gesammelten Siisswasseralgen. Arkiv for Botanik,
K. Svenska Vetensk. Akad. xv, 1918.

BULNHEIM in Hedwigia. — 0. Bulnheim, Einige Desmidiaceen.
Hedwigia, n, no. 4, 1859. Beit-rage zur Flora der Des-
midiaceen Sachsens. Hedwigia, n, no. 9, 1861.

CARTER, Chloroplasts Desmids. — N. Carter, Studies on the Chloro-
plasts of Desmids. Ann. Bot. xxxm and xxxiv, 1919-20.

CEDERGREN, Sotvattensalg. Sverige. — G. R. Cedergren, Bidrag till
kannedoinen om Sotvattensalgerna i Sverige. I. Algfloran
vid Upsala. Arkiv for Botanik, K. Svenska Vetensk. Akad.
xm, 1913.

COOKE in Grevillea 1880. — M. C. Cooke.

XV111 ADDITIONAL BIBLIOGRAPHY.

DE BARY, Cosmocladium. -A. de Bary, Ueber Cosmocladium.

Flora, 1865, p. 321.

•

DILLWYN, Confervce. — W. Dillwyn, British Confervae. London,
1802-1809.

DUCELLIER, Cat. Desm. Suisse. — F. Ducellier, Catalogue des
Desmidiees de la. Suisse et de quelques localites frontieres.
Geneve, 1914.

DUCELLIER, Contr. Flor. Desm. Suisse. — F. Ducellier, Contri-
bution a 1'etude de la flore Desmidiologique de la Suisse.
Geneve, 1916.

EHR., Org. kl. Raumes. — C. G. Ehrenberg. Dritter Beitrag zur
Erkenntnis grosser Organisation in der Richtung des klein-
sten Raumes. Physikal. Abh. k. Akad. Wiss. Berlin, 1833.
Berlin, 1834.

EHR., Meteorpap. — C. G. Ehrenberg, Ueber das im Jahre 1686
in Curland vom Himmel gefallene Meteorpapier, und iiber
dessen Zusainmensetzung aus Conferven und Infusorien.
Physikal. Abh. k. Akad. Wiss. Berlin, 1838. Berlin, 1839.

EHR., Berlin Monatsb. — C. G. Ehrenberg, Characteristik von 274
neuen Arten von Infusorien. Bericht Verhandl. Preuss.
Akad. Wiss. Berlin, 1840.

EHR., Mikr. Leh Siid. u. Nord Amerik. — C. G. Ehrenberg, Ver-
breitung und Einfluss des mieroscopischen Lebens in Siid
und Nord Amerika. Physikal. Abh. k. Akad. Wiss. Berlin,
1841. Berlin, 1843.

ESPENSCH., Desm. berg. Landes. — F. Espenschied, Die Desmidia-
ceen des bergischen Landes. Jahresbericht Naturwiss.
Verein Elberfeld, H. 10, 1903.

FRITCH, Alg. Madagascar. — F. E. Fritch, Contributions to our
knowledge of the Freshwater Algae of Africa. 1 : Some
Freshwater Algae from Madagascar. Ann. Biologic lacust.
vii, 1914.

FRITCH, Alg. Cape Peninsula. — F. E. Fritch, Contributions to
our knowledge of the Freshwater Algae of Africa. 2 : A
First Report on the Freshwater Algaa, mostly from the Cape
Peninsula, in the Herbarium of the South African Museum.
Ann. S. Afr. Museum, ix, 1919, p. 483.

ADDITIONAL BIBLIOGRAPHY. XIX

GREVILLE, Scott. Crypt. Flora. — R. K. Greville, Scottish Crypto -
gamic Flora, vi. Edinburgh, 1828.

GRIFFITHS, Plankt, N. Wore. Pooh.—B. M. Griffiths, The August
Heleoplankton of some North Worcestershire Pools. Journ.
Linn. Soc. XLIII, 1916.

GRONBLAD, Desm. Keuru. — R. Gronblad, Finnlandische Des-
midiaceen aus Keuru. Act. Soc. Flora Fauna Fenn. XLVII,
1920.

GRONBLAD, Desm. Finnland. — R. Gronblad, New Desmids from
Finnland and Northern Russia. Act. Soc. Flora Fauna
Fenn. XLIX. 1921.

HARRIS, Desm. Dartmoor. — G. T. Harris, The Desmid Flora of
Dartmoor. Journ. Quek. Micr. Club, xm, 1917.

HARRIS, Desm. Triassic Dist.—Q. T. Harris, The Desmid Flora
of a triassic district. Journ. Quek. Micr. Club, xiv, 1920.

HODGETTS, Roya anglica. — W. J. Hodgetts, Roya anglica G. S.
West, a new Desmid, etc. Journ. Bot. LVIII, 1920, p. 65.

KAISER, Alg. Traunstein Chiemgau I. — E. Kaiser, Beitrage zur
Kenntnis der Algenflora von Traunstein und Chiemgau. I.
Verzeichnis. Bayerischen Botan. Ges. Bericht. xiv, 1914,
p. 145.

KIRCHXER, Mikr. Pjianz. d. Siisswassers. — 0. Kirchner, Die
mikroskopische Pflanzenwelt des Siisswassers. Zweite
Auflage, 1891.

KOFOID, Plankt. Ill River. — C. A. Kofoid, The Plankton of the
Illinois River. Part II : Constituent Organisms and their
Seasonal Distribution. Bull. 111. State Lab. xm, 1908.

LUTKEM., Gattung Cylindrocystis. — J. Lutkemiiller, Die Gattung
Cylindrocystis Breb. Verh. zool.-bot. Ges. Wien, 1913.

MEYEN, BeobacJtt. niedere Alg. — F. J. F. Meyen, Beobachtungen

liber einige niedere Algenformen. Nov. act. physico-medica
Akad. Caesar. Leop. Carol. Nat. cur. xiv, 1828, p. 768.

PLAYFAIR, Alg. Lismore Distr. — G. I. Playfair, Freshwater Algee
of the Lismore District, etc. Proc. Linn. Soc. N. South
Wales, XL, 1915.

PLAYFAIR, Census. — G. I. Playfair, "Freshwater Algae" in Census
of New South Wales Plants. Sydney. 1917.

XX ADDETIONAL BIBLIOGRAPHY.

EABENHORST, Alg. Europe. — L. Rabenhorst, Die Algen Sachsens.
Dresden, 1850-1879 (exs.).

RALFS in Ann. Mag. Nat. Hist.— 3. Ralfs, 1843-1848.

SCHRODER, Cosmocladium Saxonicum.—R. Schroder, Cosmo-
cladium. Saoconicum De Barv. Ber. deutsch. hot. Gesellsch.
xvin, 1900.

SEXN, Ueber Coloniebild. Alg. — Semi, Ueber einige colonie-
bildende einzellige Algen. Botan. Zeitung, LVII, 1899, p. 39.

SEXX. Oocardium stratum. — G. Senn, in Zeitschrift fiir Natur-
wissensch. 1899.

SMITH, Engl. Bot. — J. E. Smith, English Botany or Coloured
Figures of British Plants, xxxv. London, 1812.

STROM, Alg. Tnddal. — K. M. Strom, Freshwater Algae from
Tuddal in Telemark. Nyt Magazin f. naturvidenskaberne,
LVII, 1919.

TRAXSEAU, Alg. Michigan. — E. N. Transeau, The Algse of
Michigan. Ohio Journ. Science, xvn. no. 7, 1917.

VIRIEUX, Alg. reg. Jurass. — J. Virieux, Contribution a 1'etude
des alques de la region jurassienne. IV : Quelques Algues
et quelques Peridiniens de Franchecomte. Bull. Soc.
d'Histoire nat. Doubs, no. xxvn, 1912-13.

Vox KEISSLER, Plankt. Hallst. Sees. — K. von Keissler, Uber das
Plankton des Hallstatter-Sees in Oberosterreich. Verhandl.
zool.-bot, Ges. Wien, 1903, p. 338.

WAHLBURG, Bidr. Jcanned. Littois-trask. — A. Wahlburg, Bidrag
till kannedomen om Littois trask med sarskild hansyn till
dess Plankton. Act. Soc. Fauna Flora Fenn. xxxvm, 1913.

WEST, Alg. Notes V-XL—G. S. West, Algological Notes V-XL
Journ. Bot, 1912, p. 79.

WEST, Alg. Colombia. — Gr. S. West, A Contribution to our know-
ledge of the Freshwater Algae of Colombia. Mem. Soc.
Neuchat. des Sci. nat. v. Neuchatel, 1914.

WEST, Alg. Notes XV.— G. S. West, Algological Notes XV.
Journ. Bot. 1915, p. 78.

WEST, Alg. Burma. — W. & G. S. West, Freshwater Algae from
Burma, etc. Ann. Roy. Bot. Gard. Calcutta, 1907.

ADDITIONAL BIBLIOGRAPHY. XXI

WEST, Period. Plankt. British Lakes.— Vf. & G. S. West, On the
Periodicity of the Phytoplankton of some British Lakes, etc.
Journ. Linn. Soc. Bot. XL, 1921.

WEST, Clare Island Alg. — W. West, " Freshwater Algae ' in
Clare Island Survey. . Proc. K. Irish Acad. xxxi, 1912.

WOLLE in Butt. Ton: Bot. Club, 1885.- -Fr. Wolle.

VOL. v.

BRITISH DESMIDIACE.E.

Genus 18. STAURASTRUM (continued).

SECTION E.

Cells furnished with spines at the angles only, each angle pro-
vided with single or binate spines, rarely with three or four.
* Cells having a single spine at each angle.

| Cell- wall smooth or minutely punctulate, never granulate
or verrucose.

42. St. glabrum.

43. St. Dickiei.

44. St. apiculatum.

45. St. dejectum.

46. St. mucronatum.

47. St. O'Mearii.

48. St. pterosporum.

49. St. connatum.

50. St. jaculiferum.

51. St. curvatum.

52. St. megacanthuni

53. St. aristiferum.

54. St. cuspidatum.

55. St. pseudocuspidatum.

56. St. leptodermum.
|f Cell-wall granulate or even verrucose.

57. St. Ungeri.

58. St. tunguscanum.

59. St. lunatum.

60. St. cornutum.

61. St. Gatniense.
** Cells with more than one spine at each angle.

| Cell- wall smooth or punctulate, never granulate.

62. St. bifidum.

63. St. longispinum.

64. St. Brasiliense.

65. St. quadrangulare.

66. St. quadrispinatum.

VOL. V. 1

BRITISH DESMIDIACE.E.

f f Cell-wall rough with tiny granules.

67. St. denticidatum.

68. St. Avicula.

69. St. subcruciatum.
60. St. cornutum.

42. Staurastrum glabrum (Ehr.) Kalfs.
(PI. CXXIX, figs. 2-5.)

Desmidium glabrum Ehr. Meteorpap. 1838, pp. 51 and 56, t. 1, f. 13 (in part).
Phycastrum glabrum Kiitz. Phyc. Germ. 1845, p. 137 ; Spec. Alg. 1849,

p. 179.
Staurastrum glabrum Ralfs, Brit. Desm. 1848, p. 217 ; Arch, in Pritch. Inf.

1861, p. 738 ; Cooke, Brit. Desm. 1887, p. 143, t. 50, f . 4 ; De Toni, Syll.

Alg. 1889, p. 1145 ; Roy, Freshw. Alg. Enbridge Lake and Vicin. 1890,

p. 337 ; Roy & Biss. Scott. Desm. 1893, p. 20 ; West & G. S. West, Some

N. Amer. Desm. 1896, p. 255, t. 16, f. 8 (var.) ; Alg. N. Ireland, 1902,

p. 44 ; Borge, Botan. Notiser, 1913, p. 28.

Phycastrum (Stenactinium) glabrum Nag. Gatt. einz. Alg. 1849, p. 128.
Staurastrum dejectum ft Debaryanum forma Borge, Sverig. Chlorophyc. II,

1895, p. 23, t. 1, f. 14.

Cells very small, about as long as broad, not in-
cluding trie spines, or sometimes a little broader than
long, deeply constricted, sinus widely open and almost
rectangular ; semicells in front view cuneate, sides
straight or very slightly convex, apex straight or slightly
concave, with a long, strongly inflexed spine at each
angle. Vertical view usually triangular, sides slightly
concave, angles ending in a sharp spine. Chloroplasts
axile, one in each semicell, with a central pyrenoid,
and a pair of lobes extending into each angle.

Zygospore "globular, spines numerous, simple, subu-
late, base broad : (Roy).

Length 16-25^ ; breadth, without spines, 15-30(JL ;
length of spines 7-10(ji; breadth of isthmus 5-7 JJL ;
diam. zygosp., without spines, 25' 6^ ; length of spines
14*4 [JL.

ENGLAND. — Cam Fell and bog near Clapham, W.
Yorks ! Mickle Fell, N. Yorks ! Bisley Common,
Surrey ! Enbridge Lake, Hants (Roy}. Devon !
(Harris). Cornwall (Marquand).

WALES. — Moel Siabod, Llyn Bochlwyd, Glyder Fach

STAURASTRUM. 3

(at 2,200 ft.), Llyn-y-cwm-nynon and Capel Curig,
Carnarvonshire !

SCOTLAND. — Common (Roy & Biss.). Khiconich,
Sutherland ! Shetlands !

IRELAND.- -Lough Nacung, Donegal ! Dublin and
Wicklow (Arch.).

Geogr. Distribution. — Germany. Austria. Sweden.
Asia Minor. United States (var.).

St. glabrum is a widely distributed but rarely abundant bog
species, whose angular form and inflexed spines readily dis-
tinguish it from all allied species.

43. Staurastrum Dickiei Ralfs.
(PL CXXIX, figs. 14, 15.)

Staurastrum Dickiei Ralfs, Brit. Desm. 1848, p. 123, t. 21, f. 3 ; Arch, in
Pritch. Inf. 1801, p. 737 ; Rabenh. Krypt. Fl. -Sachs. 18(33, p. 189; Gay,
Monogr. loc. Conj. 1884, p. 07 ; \Y«>lle, Desm. U.S. 1884, p. 122, t. 40, f. 5, 6,
t. 51, f. 20, 21 ; Cooke, Brit, Desm. 1887, p. 140, t. 49, f. 3 ; Wittr. &
Nordst. Alg. Exsic. Ease. 21, p. 37, 1889 (forma); De Toni, Syll. Alg.
1889, p. 1139 ; Anderss. Sverig. Chlor. 1890, p. 11 ; West, Ahr. \V. Ireland,
1892, p. 171 ; Alg. aq. dulc. Lusit. 1892, p. 1503 (forma) ; Liitkem. Desm.
Central China, 1900, p. 123, t. 0, f. 28, 29 (forma) ; Comere, Desm. France,
1901, p. 162, t. 13, f. 23 ; Schroder, Gallertbilcl. Alg. 1902, p. 168, t. 7,
f. 18; G. S. West, Brit. Fivsliw. Alg. 1904, p. 141, f. 52, A-C ; Borge,
Siissw. Alg. Spitzb. 1911, p. !'.».

Didt/ in nl ium (Staurastrum) concergens B trigona Reinsch, Algenfl. Frank.
1807, p. 154.

Staurastrum brevispimun (3 Dickiei Rabenh. Flor. Europ. Alg. 1868, p. 202.

St. dejectum /3 Dickiei Jacobs. Desm. Danem. 1875, p. 204.

St. laniatum Delp. Desm. subalp. 1877, p. 135, t. 10, f. 17 (in part).

St. forcipatum Playfair, NCAV or less-known Desm. X. S.Wales, 1907, p. 182,
t. 5, f. 1.

Cells rather small, about as long as broad, not in-
cluding the spines, deeply constricted, sinus open and
acute-angled with a slightly rounded apex ; semicells
subelliptic in outline, dorsal and ventral margins almost
equally convex, or the ventral margin a little more
convex than the dorsal ; angles terminating in a short,
very slightly recurved spine, directed towards the other
semi cell. Vertical view triangular, lateral margins
somewhat concave, angles rather inflated, each with a
short spine. Chloroplasts one in each semicell, with a

4 BRITISH DESMIDIACE^E.

central pyrenoid and a pair of lobes extending into
each angle.

Zygospore globose, covered with numerous long spines,
broader at the base.

Length = breadth (not including the spines) = 34-44 JJL ;
length of spines 4-5 [JL ; breadth of isthmus 5-7 y. ;
diam. zygosp., without spines, 39 ^ ; length of spines 11 pi.

ENGLAND. — Cumberland ! Westmoreland (Biss.) I
Lancashire ! W., N., and E. Yorks ! Leicestershire
(Roy}. King's Norton, Worcs ! Surrey (zygospores
from Puttenham Common) ! Hants ; zygospores from
New Forest (Roy) I Kent ! Devon (Harris). Cornwall
(Marquand) \

WALES. — Moel Siabod, bog between Glyder Each and
Llugwy, Llyn Idwal, Llyn Padarn and Capel Curig,.
Carnarvonshire ! Dolgelly, Merioneth (Rolfs).

SCOTLAND. — General; zygospores from Aberdeen and
Kincardine (Roy & Biss.). Near Lochmaddy, N. Uist
and in Lewis, Outer Hebrides ! Shetlands ! In the
plankton !

IRELAND.- -Donegal ! Mayo ! Clalway ! Plankton of
Lough Caragh, Kerry ! Dublin and Wicklow (Arch.).
Armagh ! Down !

Geogr. Distribution.- -France. Germany. Switzerland.
Austria. Hungary. Servia. Portugal. Norway. Sweden.
Denmark. Bornholm. Finland. Poland. N. Russia.
Faeroes. Nova Zembla. Spitzbergen. Greenland.
Siberia. Central China. Japan. E. India. Australia.
New Zealand (var.). Madagascar (var.). Central Africa.
United States. Brazil. Paraguay. Patagonia.

St. Dickiei is a most ubiquitous Desmid and frequently occurs
in great abundance in gatherings from bogs and marshes. It is
only very rarely found in plankton. By reason of its broadly
elliptical semicells, and slightly inflexed spines, it is a species
which is very easily recognised.

Forma punctata West.

St. Dickiei forma punctata West, Alg. W. Ireland, 1892, p. 18 ; Clare Island
Alg. 1912, p. 21.

STAURASTRUM. 5

A form with the cell-wall minutely punctate ; in all
other respects quite similar to the type.

ENGLAND. — Bowness, Westmoreland ! Thursley Com-
mon, Surrey !

IRELAND. — Near Westport, Mayo ! Clifden and Bally-
nahinch, Galway ! Adrigole, Cork !

Var. circulare Turn. (PL CXXIX, fig. 16.)

*S7. DirJcieiv&r. circulare Turn. Fresh w. Alg. E. India, 1893, p. 105, t. 16, f. 5 ;

West & G. S. West, Some X. Amer. Desm. 1896, p. 255.
St. Dickiei var. semicirculare West & G. S. West, Alg. S. England, 1897,

p. 492.
St. brevispinum Hustedt, Desm. Bac. Tirol, 1911, p. 338, f. 28.

Cells nearly circular in outline, not quite so deeply
constricted as in the type ; semicells nearly semicircular,
sinus linear in the median part, finally opening more
widely. Spines straight and considerably shorter than
in the type, very strongly inflexed, and attached at the
basal angles of the semicell.

Length 24-40 \L ; breadth 26-40 p ; breadth of isthmus
8-12 (JL ; length of spines 2-3 JJL.

ENGLAND.- -Thursley Common, Surrey !

Geogr. Distribution. --Poland. India. Central Africa.
United States.

This variety is well defined from the type by reason of its
semicells with, very strongly convex apex and short, straight, and
strongly inflexed spines, which project from the basal angles of
the semicell.

Var. rhomboideum West & G. S. West, (PL CXXIX,

fig. 17.)

-67. Dickiei var. rhomboideum West & G. S. West, Scott. Freshw. Plankt. I,
1903, p. 545, t. 16, f. 9.

Semicells distinctly rhomboidal in shape ; spines
rather longer, and strongly incurved.

Length 37 pi ; breadth, without spines, 38 '5-46 [JL ;
length of spines 6-9 'opt ; breadth of isthmus 8 '5 pi.

SCOTLAND.- -Plankton of Loch nan Eun, N. Uist,
Outer Hebrides !

6 BRITISH DESMIDIACEJE.

44. Staurastrum apiculatum Breb.
(PL CXXIX, figs. 6-8.)

Staurastrum apiculatum Breb. Liste Desm. 185(5, p. 142, t. 1, f. 23 ; Arch.

in Pritch. Inf. 1861, p. 737 ; in Q. J. M. S. 1868, p. 67 ; Cooke, Brit. Desm.

1887, p. 139, t.49, f. 2; Borge, Siissw. Chlor. Archang. 1894, p. 37; Roy

& Biss. Scott. Desm. 1893, p. 16 ; West & G. S. West, Some N. Amer.

Desm. 1896, p. 254, t. 16, f. 6 ; Freshw. Chlor. Koh Chang, 1901, p. 92 ;

. Alg. Yorks. 1902, p. 96 ; Alg. N. Ireland, 1902, p. 44 ; Georgev. Desm.

Macedonia, 1910, p. 243 ; Borge, Botan. Notiser, 1913, p. 28.
St. dejectum var. apiculatum Lund. Desm. Suec. 1871, p. 59 ; Kirchn. Alg.

Schles. 1878, p. 169 ; Wille, Norges Ferskv. Alg. 1880, p. 40 ; Comere,

Desm. de France, 1901, p. 161, t. 12, f. 30 ; Him, Desm. Filmland, 1903,

p. 20, t. 2, f. 30.
St. dejectum a Jacobs. Desm. Danem. 1875, p. 203.

Cells small, about as long as broad, deeply constricted,
sinus widely open, with its apex acutely rounded ; semi-
cells rather wine-glass shaped, dorsal margin almost
straight, only slightly convex, or even a little concave,
ventral margin nearly semicircular ; with a minute
acute spine at each angle which is dorsal rather than
lateral in its attachment, and is directed vertically
upwards. Vertical view triangular, lateral margins
slightly concave, angles somewhat turgid and provided
with a minute mucro at each extremity.

Zygospore spherical, provided with numerous simple
acute spines.

Length = breadth = 18-29 \L ; breadth of isthmus 5*5-
7 \L ; diam. zygosp., without spines, 23 \L ; length of
spines 6\i.

ENGLAND. — Cumberland ! Westmoreland (Biss.) I
W., N., and E. Yorks ! Cambridge ! Surrey (zygo-
spores from Thursley Common) ! Hants (Roy] ! Devon
(Harris}. Cornwall (Marquand) I

WALES.- -Not uncommon !

SCOTLAND. — General, but scarce ! With zygospores
from Slewdrum, Aberdeen (Roy & Biss.}.

IRELAND.- -Donegal ! Mayo and Clare Island ! Gal-
way ! Kerry ! Dublin and Wicklow (Arch.}. Louth !
Down ! Londonderry ! Plankton of Lough Neagh ! of
Galway ! and of Kerry !

Geogr. Distribution.- -France. Germany. Galicia in

STAURASTRUM. 7

Austria. Turkey in Europe. Norway. Sweden. Den-
mark. Finland. N. Russia. W. Greenland. Japan.
Burma. Siam. Australia. United States.

St. apiculatum is very closely allied to St. dejectum, St. mucro-
natum and others, but is readily distinguished from all similar
forms by the shape of its semicells, with their nearly straight
apices and minute spines projecting vertically upwards. It is
quite a common species and is widely distributed.

The original description of the zygospore given by de Brebisson
and copied by Cooke and others is inaccurate, since the zygo-
spores have numerous sharp spines, not blunt ones with broad
bases.

45. Staurastrum dejectum Breb.
(PI. CXXIX, figs. 9-12.)

BinateUa dejecta Breb. Alg. Falaise, 1835, p. 269.

Staurastrum dejectum Breb. in Menegh. Synops. Desm. 1840, p. 227 ; Ralfs,
Brit. Desm. 1848, p. 121, t. 20, f. 5 (ex parte) ; Breb. Liste Desm. 1856,
p. 142 ; De Bary, Conj. 1858, p. 50, t. 6, f. 25-32 ; Arch, in Pritch. Inf.
1861, p. 737 ; Rabenh. Krypt, Fl. Sachs. 1863, p. 189 ; Wood, Freshw.
Alg. N. Airier. 1873, p. 148, t. 21, f. 18, t. 13, f. 9 ; Kirchn. Alg. Schles.
1878, p. 168 ; Wille, Norges Ferskv. Alg. 1880, p. 40 ; Wolle, Desm. U. S.
1884, p. 121, t. 40, f. 7-11, 17-22 (ex parte) ; Lagerh. Bidr. Amerik. Desrn.-
fl. 1885, p. 247 ; Cooke, Brit. Desm. 1887, p. 138, t. 49, f. 1 ; De Toni,
Syll. Alg. 1889, p. 1137; West, Alg. W. Ireland, 1892, p. 170 ; Alg. Engl.
Lake Distr. 1892, p. 18 ; Schmidle, Beitr. Algenfl. Schwarzwald u. Rheineb.
1893, p. 107, t, 5, f. 26, 27 (forma) ; Roy & Biss. Scott. Desm. 1894, p. 19 ;
Schmidle, Beitr. Alp. Alg. 1895, p. 30, t. 16, f. 30, 31 ; W. & G. S. West,
Alga-fl. Yorks. 1901, p. 96 ; Comere, Desm. de France, 1901, p. 161, t. 13,
f. 18 ; W. & G. S. West, Alg. N. Ireland, 1902, p. 44 ; Freshw. Alg. Ceylon,
1902, p. 175; Scott. Freshw. Plankton, I, 1903, p. 528; Freshw. Alg.
Orkneys and Shetlands, 1905, p. 24 ; Coinp. Study Plankton Irish Lakes,
1906, p. 86 ; Gutw. Flor. Alg. Mont, Tatr. 1909, p. 470 ; Kaiser, Beitr. Alg.
Traunstein Chiemgau, 1914, p. 152.

St. mucronatum Ralfs in Ann. Mag. Nat. Hist. 1845, p. 152, t. 10, f. 5 (ex
parte).

St. cuspidal um v. dejectum Kiitz. Spec. Alg. 1849, p. 179.

Didymidium (Staurastrum) erectum Reinsch, Alg. Frank, 1867, p. 157 (ex
parte) ; Contr. Alg. Fung. 1875, p. 86, t. 15, f. 8.

Staurastrum laniatum Delp. Spec. Desm. Subalp. 1877, p. 39, t. 10, f. 25 (in
part).

St. dejectum var. a lunatum Cooke, Brit. Desm. 1887, p. 138, t. 49, f. la.

St. dejectum f. punctata West, Add. Alg. W. Yorks. II, 1891, p. 247.

Cells small, about as long as broad (not including the
spines), deeply constricted, sinus widely open, acute or
obtusely rounded at the apex, often nearly rectangular ;
semicells usually more or less triangular in outline,

8 BRITISH DESMIDIACE.E.

rarely elliptical, dorsal and lateral margins nearly
straight or very slightly convex ; with a long spine at
each angle ; spines usually somewhat diverging, some-
times parallel, and very rarely converging. Vertical
view triangular, rarely quadrangular, lateral margins
slightly concave, angles slightly turgid and terminated
by a strong spine. Chloroplast axile with a central
pyrenoid and two lobes projecting into each angle.

Zygospore spherical, with a number of rather short,
stout spines, broad at their base.

Length, not including the spines, 18-27^ ; breadth,
not including the spines, 17-27 (JL ; breadth of isthmus
5-8 (JL ; length of spines 3-8 [JL ; diam. zygosp., without
spines, 32'5 (JL ; length of spines, 5-10 [JL.

ENGLAND. — Cumberland ! Westmoreland ! Lanca-
shire (Rolfs}. W., N., and E. Yorks! Essex! Warwicks
(Wills). Surrey ! Sussex ! Kent (Rolfs). Hants !
Wilts ! Devon ! (Harris). Cornwall ! Plankton of
Ennerdale Water, Cumberland, and of Hawes Water
and Stickle Tarn, Westmoreland !

WALES. — Capel Curig (Cooke & Wills), Llyn Idwal,
Llyn Ogwen, Llyn C4eirionedd, Llyn Bodgynwydd and
Y Foel Eras, Carnarvonshire ! In the plankton.

SCOTLAND. — General : zygospores not uncommon (Roy
& Biss.). Bute ! Loch Doon, Ayrshire ! Wigtownshire !
Lewis and Harris, Outer Hebrides ! General in the
plankton !

IRELAND. — Donegal ! Mayo and Clare Island ! Gal-
way ! Kerry ! Dublin and Wicklow (Arch.). London-
derry ! In the plankton !

Geogr. Distribution. — France. Germany. Switzerland.
Austria and Galicia. Hungary. Servia. Italy. Norway.
Finmark. Sweden. Poland. N., Central and S. Russia.
Faeroes. Iceland (var.). Greenland. Siberia. Mongolia.
Central China. Japan. India. Ceylon. Australia. New
Zealand (var.). E. Africa. Alaska. LTnited States.
Canada. Colombia.

St. dejectum is an extremely common and widely distributed

STAURASTRUM. 9

species and, at the same time, it is somewhat variable in form
and in the inflexion of its spines. These are usually inserted near
the apex of the semicell and are, as a rule, slightly divergent
or parallel. The more or less triangular form of the semicells
and the dorsal insertion of its spines are the features by which
it can be distinguished from St. mucronatum. In the latter
species the semicells are more elliptical in form and the spines
are lateral in their insertion.

There has been much confusion in the past between St. dejec-
tum and St. mucronatum, particularly with regard to the zy go-
spores. Kalfs (in ' Brit. Desm.' 1848) united the two species
and figured them under the name of St. deject um. The con-
jugating specimens figured by him belong most probably to St.
mucronatum., as is evident from the shape of the semicells (see
' Nordst. Freshw. Alg. N. Zeal.' 1888, p. 40). These zygospores
have been copied by many authors and reproduced under the
name of St. dejection. The zygospore of St. dejection is, however,
not well known, since it has only been figured by De Bary (' Conj.'
1858, t. 6, f. 26-32) and Eeinsch (' Contrib. Alg. Fung.' 1875, 1. 15,
f. 8).

Forma major West & G. S. West. (PL CXXIX, fig. 13.)

Stauraslruni dejectum forma West & G. S. West, Comp. Study Plankton
Irish Lakes, 1900, p. 102, t. 11, f. 1(3.

Differs from the type in its larger size and much
stouter spines.

Length, without spines, 42 pt ; breadth, without spines,
48 pi ; breadth, including spines, 80-85 u ; breadth of
isthmus 11 (JL.

IRELAND.- -Plankton of Lough Corrib, Galway !

Var. patens Nordst. (PI. CXXX, figs. 1, 2.)

Stanrasfnun dejectum /3 patens Xordst. in Botan. Xotis. 1887. p. 158 ; Freshw.
Alg. N. Zeal. 1888, p. 39, t. 4, f. 16 ; De Toni, Syll. Alg. 1889, p. 1138;
\Vest, Alg. Engl. Lake Distr. 1892, p. 18 ; Borge, Siisswasseralgen Siid-
Patagon. 1901, p. 27, t. 1, f. 11 ; Gutw. Flor. Alg. Mont. Tatr. 1909,
p. 470 ; Borge, Sao Paulo Siisswasseralgen, 1918, p. 47.

A form with small spreading spines which are diver-
gent ; sinus acute-angled, isthmus not even slightly
elongated.

10 BRITISH DESMIDIACE.E.

Length 21-26 pi ; breadth 21-25 (JL ; breadth of isth-
mus 6-7 [JL ; length of spines up to 2*5 pi.

ENGLAND.- -Brother's Water, Westmoreland! En-
bridge Lake, Hants (Rot/).

SCOTLAND. — Alford and Tomachar, Aberdeen (Roy &
Biss.).

Geogr. Distribution.- -Finland. Italy. Austria. Aus-
tralia. New Zealand. Brazil. Patagonia.

The more elliptical and inflated form of the semicells and the
small spreading spines seem to be characteristic of this variety.

Var. inflatum West. (PI. CXXX, figs. 3-5.)

Staurastrum dejectum var. inflatum West, Alg. W. Ireland, 1892, p. 170, t. 22,
f. 11 ; West & G. S. West, Alg. N. Ireland, 1902, p. 44 ; Freshw. Alg.
Orkneys and Shetlands, 1905, p. 24 ; Borge, Botan. Notis. 1913, p. 27.

Cells much larger than in the type, semicells more
elliptical in form and very inflated, sinus acute, spines
at the angles much shorter and directed outwards.

Length, without spines, 35*5-43 \JL ; breadth, without
spines, 33*5-52 ^ ; breadth of isthmus 10*3-12 pi ; length
of spines 2*8-4*3 p.

WALES.- -In the plankton !

SCOTLAND.- -Loch Ruar, Sutherland ! Plankton of
Loch Mor Bharabhais and Loch Cuthaig, Lewis, Loch
Laxadale, Harris, and Loch nan Eun, N. LHst, Outer
Hebrides ! Plankton of the Orkneys and Shetlands !

IRELAND.- -Derryclare Lough, Ballynahinch, and in
the plankton of Lough Corrib, Co. Galway ! Plankton
of Lough Neagh and Lough Beg, Londonderry !

Geogr. Distribution. — Sweden. Norway.

This large variety is more frequent in plankton than in any
other habitat. Borge (' Botan. Notiser.' 1913, p. 27) suggests
that it is simply a large form of var. patens Nordst., and certainly
it does resemble this variety in the form of its semicells.

ST. DEJECTUM var. CONVERGENS Wolle, ' Desm. U. S.' 1884,
p. 121, t. 40, f. 7, 9-11 ; De Toni, ' Syll. Alg.' 1889, p. 1138;
Harris in " Journ. Quek. Micr. Club,' 1920, p. 25. Harris (loc.

STAURASTRUM. 1 1

cit.) records this variety for Woodbury Common, E. Devon,
which is the first British locality for it. Exactly what Wolle
intended us to understand by his variety convergens is difficult
to decide. His figures are very bad, and some of them bear a
strong resemblance to St. glabrum (Ehr.) Kalfs, or to ArtJiro-
desmus convergent Ehr. The writer is of the opinion that Wolle's
description and figures are wholly inadequate as the basis of a
valid variety, and believes that specimens recorded under this
name have in all probability been either forms of Staurastrum
glabrum or simply St. dejection with slightly convergent spines.

46. Staurastrum mucronatum Ralfs.
(PL CXXX, figs. 10-12.)

Staurastrum mucronatum Ralfs in Ann. Mag. Xat. Hist. 1845, p. 152, t. 10,
f. 5, 6 (ex parte) ; Breb. Liste Desm. 1856, p. 142 ; Xordst. Desm.
Spetsb. 1872, p. 38 ; Gay, Monogr. loc. Conj. 1884, p. 67 ; Roy & Biss.
Scott. Desm. 1894, p. 22; West & G. S. West, Alga-fl. Yorks. 1902,
p. 96 ; Ale. X. Ireland, 1902, p. 44, t. 2, f. 31 ; Borge, Botan. Xotis. 1913,
p. 28.

Goniocystis (Trigonocystis) mucronata Hass. Brit. Freshw. Alg. 1845, p. 350,
t. 84, f.8 (ex parte).

Staurastrum dejectum ft Ralfs, Brit. Desm. 1848, p. 121, t. 20, f. 5 (ex parte).

Phycastrum (Amblyactinium) mucronatum Xiig. Gatt. einz. Alg. 1849, p. 125.

Staurastrum dejectum forma Reinsch, Contrib. Alg. et Fung. 1875, p. 90,
t. 13, f. 7.

St. dejectum var. mucronatum Kirchn. Alg. Schles. 1878, p. 169 ; Wolle,
Desm. U. S. 1884, p. 121, t. 40, f. 8 ; Cooke, Brit. Desm. 1887, p. 139
t. 55, f. 7 ; De Toni, Syll. Alg. 1889, p. 1137 ; Gutw. Xonn. Alg. Xov.
1896, p. 27, t. 7, f. 69;' Comere, Desm. de France, 1901, p. 161, t. 12,
f. 28 ; Teodoresco, Mater, flor. alg. Rouman. 1907, p. 183.

Cells small, about as long as broad, deeply constricted,
sinus open and acute-angled ; semicells elliptic, dorsal
margin more convex than in St. dejectum, ventral margin
more convex than the dorsal ; angular spines rather
short, projecting horizontally, rarely converging. Ver-
tical view usually triangular, lateral margins concave,
angles very turgid, ending in a short stout spine. Criloro-
plast axile with a central pyrenoid, and a pair of lobes
stretching into each angle.

Zygospore spherical, furnished with numerous conical
spines.

Length 22-26 y. ; breadth, without spines, 18-25 a. ;
length of spines 3-3*5 y. ; breadth of isthmus 6 '7-7 [j. ;

12 BRITISH DESMIDIACE^;.

diam. zygosp., without spines, 33'7 JJL ; length of spines
12-5 p.

ENGLAND.- -Wastdale, Cumberland ! Helvellyn and
near Bowness, Westmoreland (Biss.). Cullingworth
and near Settle, W. Yorks ! Mickle Fell and Pilmoor,
N. Yorks ! Risley Bog (Roy] and Hampsfell, Lanca-
shire ! Leicester (Roy). Enbridge Lake, Hants (Roy).
Keston Common, Kent !

WALES. — Capel Curig, Carnarvonshire !

SCOTLAND. — General, but scarce (Roy & Biss).

IRELAND.- -Lough Gartan, Donegal ! Dublin and
Wicklow (Arch.).

Geogr. Distribution.- -France. Germany. Galicia in
Austria. Roumania. Norway. Sweden. Bornholm.
Poland. Spitzbergen. Siberia. N. India. United
States. Alaska.

This species is not quite as common as St. dejectum, to which
it is very closely allied. It is distinguished from the latter by
its more convex apex and elliptical semicells, whilst its laterally
inserted spines, which are rather small, are either parallel or
more rarely slightly converging. In St. dejectum the semicells
are cuneate rather then elliptic.

Var. subtriangulare West & G. S. West. (PL CXXX,

figs. 13, 14.)

St. mucronatum var. subtriangulare W. & G. S. West, Scott. Freshw. Plankton,
I, 1903, p. 545, t. 17, f. 11 ; Freshw. Alg. Burma, 1907, p. 213, t. 15,
f. 20 ; Borge, Botan. Notiser, 1913, p. 28.

Cells rather larger than in the type, the sinus more
widely open ; dorsal margin of semicell nearly straight
or slightly convex, ventral margin nearly semicircular.

Length 26-44 (JL ; breadth, without spines, 29-44 pi ;
length of spines 3'8-4'6(ji ; breadth of isthmus 6-13 (JL.

ENGLAND.- -Plankton of Grasmere, Westmoreland !

WALES.- -In the plankton !

SCOTLAND. --Plankton of Loch Doon, Ayrshire !

Geogr. Distribution. — Sweden. Finland. Burma.

STAURASTRUM. 13

47. Staurastrum O'Mearii Arch.
(PL CXXXII, figs. 5-8.)

Staurastrum O'Mearii Arch. Suppl. Cat. Desm. 1858, p. 254, t. 21, f. 8-13 ;
in Pritch. Infus. 1861, p. 738 ; Rabenh. Flor. Europ. Alg. 1868, p. 204 ;
Nordst. Xorges Desm. 1873, p. 27 ; Arch, in Journ. Bot. 1874, p. 93 ;
Gay, Monogr. loc. Conj. 1884, p. 66 ; Cooke, Brit. Desm. 1887, p. 142,
t. 50, f. 1 ; De Toni, Syll. Alg. 1889, p. 1143; Liitkem. Desm. Attersees,
1893, p. 563 ; Roy & Biss. Scott. Desm. 1894, p. 23 ; West & G. S. West,
Alg. S. Engl. 1897, p. 493 ; Comere, Desm. de France, 1901, p. 163, t. 11,
f. 22 ; West & G. S. West, Alg. N. Ireland, 1902, p. 44 ; Georgev. Desm.
Wlasina-See, 1909, p. 203 ; Borge, Botan. Notis. 1913, p. 28.

St. Pseudincus Reinsch, Spec. Gen. Alg. 1867, p. 15, t. 5, c.II, f. 1-5 (ex
parte = = f. 2-gona).

Arthrodesmus Incus v. iiitfnnedius Wittr. Skandinav. Desm. 1869, p. 15,
t. 1, f. 6 (f. 2-gona) ; Jacobs. Desm. Danem. 1875, p. 205, t. 8, f. 26,
b & c.

Cells very small, about as long as broad, constriction
not very deep, sinus rectangular, somewhat acute at
its apex ; semicells triangular, apex broad and truncate,
lateral margins very slightly convex, upper angles sub-
acute and each furnished with a fairly stout diverging
spine. Vertical view 2-4- (usually 3-) angled, sides very
slightly convex, angles with a stout spine.

Zygospore spherical, with numerous long and delicate
spines.

Length, without spines, 12-17[x; breadth, without
spines, 10-18*5 ^ ; breadth of isthmus 5-8 (JL ; length of
spines 5-1 0 ku. ; diam. zygosp., without spines, 12-14pu

ENGLAND.- -Borrowdale, Cumberland ! Near Bow-
ness (Biss.), Helvellyn, Scandale and Stickle Tarn, West-
moreland ! Cocket Moss, near Griggleswick, and bog
2 miles south of Clapham, W. Yorks ! Puttenham and
Thursley Commons, Surrey ! Enbridge Lake, Hants
(Roy}. Dartmoor, Devonshire (Harris). Halgavor
Moor, Cornwall !

WALES. — Capel Curig, Snowdon, and Glyder Fach
(at 2,200 ft.), Carnarvonshire ! Ffestiniog, Merioneth !

SCOTLAND. — Sutherland, Aberdeen, Kincardine, For-
far, Perth, Argyle and Arran (Roy & Biss.). Orkneys !

IRELAND. - -Donegal ! Galway ! Kerry! Dublin and
Wicklow (Arch.). Down !

14 BRITISH DESMIDIACE.E.

Geogr. Distribution.- -Fiance. Austria. Servia. Nor-
way. Sweden. United States. Colombia.

In the sterile condition this species can scarcely be distinguished
from the one following, namely, St. pterosporum Lund. When
zygospores are present the two cannot be confused, since the
zygospores of St. O'Mearii are spherical and spiny, whilst in
St. pterosporum they are smooth and angular. The sterile cells
of St. 0 Mearii are somewhat larger than those of St. ptero-
sporum, whilst the spines are also considerably longer and stouter.
It is also very similar to some forms of St. dejectum, but is usually
smaller and less deeply constricted.

Var. minutum West. (PL CXXXII, fig. 9.) :

Staurastrum 0" Mearii var. minutum West, Alg. W. Ireland, 1892, p. 172,
t. 22, f. 15.

Cells minute, smaller than in the typical form, a
little shorter than broad, excluding the spines, apex of
semicells slightly concave, spines proportionately longer ;
angles in vertical view extremely acute.

Length, without spines, 7-8 pi ; breadth, without
spines, 10 [i ; length of spines lOjz ; breadth of isthmus

5 {/,.

SCOTLAND. — Lewis, Outer Hebrides !
IRELAND. — Cromagloun, Co. Kerry !

48. Staurastrum pterosporum Lund.
(PL CXXXII, figs. 1-4.)

Staurastrum pterosporum Lund. Desm. Suec. 1871, p. 60, t. 3, f. 29 ; Arch,
in Ann. Mag. Nat. Hist. 1881, p. 233 ; Cooke, Brit, Desm. 1887, p. 143,
t. 50, f. 2 ; ? Nordst. Freshw. Alg. N. Zealand, 1888, p. 40 ; De Toni,
Syll. Alg. 1889, p. 1143 ; Gutw. Flor. Glon. Okolic Lwowa, 1891, p. 65 ;
Roy & Biss. Scott. Desm. 1894, p. 24 ; ? West & G. S. West, Some N. Amer.
Desm. 1896, p. 256 ; Alg. N. Ireland, 1902, p. 44 ; Brit, Freshw. Phyto-
plankton, 1909, p. 203 ; George v. Desm. Wlasina-See, 1909, p. 203 ;
G. S. West, Contrib. Freshw. Alg. Columbia, 1914, p. 1045.

Cells minute, about as long as broad, constriction
not very deep, sinus widely open, acute at the apex ;
semicells somewhat cuneate, broadening towards the
apex, which is broadly truncate ; sides straight or very

STAURASTRUM. 15

slightly convex, upper angles subacute, and tipped
with a very delicate spine. Vertical view triangular,
very rarely biradiate, lateral margins in the triangular
form straight or slightly concave, angles rounded, each
with a minute spine.

Zygospore compressed, rectangular, angles produced
and each lodged in one of the four semicells of the con-
jugating cells, whose form they simulate.

Length, without spines, = breadth without spines =
10-15 (z ; breadth of isthmus o'o-6'o u ; length of spines
2-4 (j. ; length of zygospore 20 [JL ; breadth 13;ji.

ENGLAND. --Near Bowness, Westmoreland (Biss.).
Delamere, Cheshire (Roy). Dartmoor, Devonshire
(Harris).

WALES. — Glyder Fawr, Carnarvonshire (Roy).

SCOTLAND. --Not uncommon : zygospore from near
Aboyne, Aberdeen (Roy & Biss.). Sutherland !

IRELAND.- -Lough Anna, Lough Machugh and near
Glenties, Donegal ! Adrigole, Co. Cork ! Dublin and
Wicklow (Arch.).

Geogr. Distribution. — Servia. Galicia in Austria.
Sweden. Finland. Greenland. New Zealand. United
States. Colombia.

This species is very similar to the preceding one, from which
it can scarcely be distinguished in the sterile condition (see above).
It is fairly widely distributed in the British Isles, but is probably
frequently overlooked. It is very much more common in the
western parts, however, than in other localities. The biradiate
form is known from Austria.

49. Staurastrum connatum (Lund.) Roy £ Biss.

(PL CXXX, figs. 6-8.)

Staurastrum dejectum var. connatum Lund. Desm. Suec. 1871, p. 60, t. 3,
f. 28 ; Wille, Norges Ferskv. Alg. 1880, p. 41; Turn. Freshw. Alg. E. India,
1893, p. 106.

St. hexacanthum Gay, Monogr. loc. Conj. 1884, p. 67, t. 2, f. 9 (forma).

St. connatum Roy &^Biss. Jap. Desm. 1886, p. 237 ; De Toni, Syll. Alg. 1889,
p. 1138 ; Borg. Desm. Brasil. 1890, p. 44 ; West, Freshw. Alg. W. Ireland,
1892, p. 171 ; Roy & Biss. Scott. Desm. 1894, p. 18 ; West & G. S. West,
Alga-fl. Yorks. 1902, p. 96 ; Alg. N. Ireland, 1902, p. 43 : Freshw. Alg.
Ceylon, 1902, p. 175 ; Hustedt, Desm. et Bacill. aus Tirol, 1911, p. 339.

16 BRITISH DESMIDIACE^:.

Cells small, about as long as broad, or up to Ij times
longer than broad, excluding the spines, deeply con-
stricted, sinus subrectangular, often acute at the apex,
opening broadly ; semicells obversely subsemicircular,
ventral margin very strongly convex, dorsal margin
nearly straight, or even slightly concave, upper angles of
semicells somewhat acutely rounded, with a long erect
spine projecting from each. Vertical view triangular,
lateral margins slightly concave, angles broadly rounded,
spines very small (as a result of foreshortening).

Zygospore of type unknown, but probably more or
less rounded, with a few short stout conical spines (cf.
zygote of var. Spencerianum, PL CXXX, fig. 9).

Length, without spines, 21-29*5 [j, ; breadth 20-22 '5 pi;
breadth of isthmus 6 '6-9 '2 (JL ; length of spines 8-13 [i.

ENGLAND. — Strensall Common, N. Yorks (W. B.
Turn.). Eiccall Common, E. Yorks ! Dartmoor,
Devonshire ! Gunwen Moor, Cornwall !

WALES.- -Bettws-y-coed (Roy), and Capel Curig !
Carnarvonshire.

SCOTLAND. — General (Roy & Biss.). Rhiconich,
Sutherland !

IRELAND.- -Lough Anna and near Lough Magrath,
Donegal ! Dublin and Wicklow (Arch.). Lough
Derryadd, Armagh !

Geogr. Distribution. — Austria. Norway. Finmark.
Sweden. Bornholm. Finland. Poland. Central China.
Japan. Turkey in Asia. Ceylon. Australia. New
Zealand. United States. Brazil.

St. connatum is widely distributed but is not quite as common
as some of the other allied species. The form of its semicells
and its long erect spines readily distinguish it from all other
Desmids of the Staurastrum dejectum series.

50. Staurastrum jaculiferum West.
(PL CXXX, figs. 17, 18 ; PL CXXXI, figs. 1-3.)

Staurastrum jaculiferum West, Alg. W. Ireland, 1892, p. 172, t. 22, f. 14;
Racib. Desra. Tapakoomas, 1895, p. 34 ; Borg. Freshw. Alg. Faeroes,

STAURASTRUM. 17

1901, p. 232, t. 8, f. 1 ; West & G. S. West, Scott. Freshw. Plankton, I,
1903, p. 543, t. 17, f. 1-4; Further Contrib. Freshw. Plankton Scott.
Lochs, 1905, p. 485, t. 1-5 ; Comp. Study Plankton Irish Lakes, 1906,
p. 103, t. 11, f. 17-19; Brit. Freshw. Phytoplankton, 1909, p. 168;
Phytoplankton Engl. Lake Distr. 1909, p. 189 ; Period. Phytoplankton
Brit, Lakes, 1912, p. 417.

Arthrodesmus longicornis Roy & Biss. Scott. Desm. 1894, p. 28 (fornia
biradiata}.

Cells small, about 1^ times longer than broad, deeply
constricted, sinus acute-angled, widening considerably ;
semicells roughly triangular, lateral margins convex,
and apex subconvex, the upper angles provided with
very long, strong and diverging spines. Vertical view
2-4-radiate, lateral margins convex, with a strong spine
at each angle. Chloroplast axile, with a central pyrenoid
and a pair of lobes stretching into each angle.

Zygospore unknown.

Length, without spines, 20-31 \L ; breadth, without
spines, 14-22 pt ; length of spines 15-38pL ; breadth of
isthmus 5*5-8 \L ; thickness (in forma brradiata) 12'5-
14 JJL.

ENGLAND. Plankton of Buttermere, Crummock
Water, Ennerdale (f . 2-radiata) and Wast Water, Cumber-
land ! Plankton of Brother's Water, Red Tarn (f. 2-
and 3-radiata3), Hawes Water, Codale Tarn, Easedale
Tarn, and Windermere, Westmoreland !

WALES.- -In the plankton (f. 2-radiata). Llyn Cwlyd,
Carnarvonshire !

SCOTLAND. --Fairly general in the plankton of the
mainland (both 2- and 3-radiate forms), of the outer
Hebrides, and of the Orkneys and Shetlands !

IRELAND.- -Lough Guitane, and common in the plank-
ton, Co. Kerry ! Rare in the plankton of Lough Keel,
and Lough Gall (f. 2-radiata), Co. Mayo !

Geogr. Distribution. --Noiw&y. Finmark. Finland.
Faeroes. Greenland. Guiana.

St. jaculiferum is almost entirely confined to plankton, or is
otherwise an inhabitant of large lakes. In some of the lakes in
S.W. Ireland and W. Scotland it forms a very prominent feature
of the plankton, and it is also fairly general in the plankton of
the Welsh, lakes, and of the English Lake District, but is apparently

VOL. V. 2

18 BRITISH DESMIDIACE.E.

wanting in the plankton of the Midlands. Thus it is a truly
western type of Desmid, being confined to the drainage area of
the older palaeozoic rocks (see W. and G. S. W., ' Brit. Freshw.
Plankton/ 1909, p. 202).

St. jaculiferum occurs in 2-4-radiate forms, the biradiate form
occurring in some plankton collections to the exclusion of all
other forms. The 3-radiate form is, however, the usual one,
and the 4-radiate form is comparatively rare. It has been proved
beyond all doubt that Arthrodesmus longicornis Roy & Biss. is
simply the biradiate form of this species, since specimens are
occasionally met in which one semicell is of the 2-radiate
form and the other 3-radiate. The biradiate form is also often
characterised by its slightly longer isthmus, and less divergent
spines. The inflexion of the spines seems, however, to be subject
to much variation in all forms of the species, the spines being
sometimes nearly parallel, and in other cases very divergent.

The species is very well defined, and is nearest to St. aristi-
ferum Ralfs, from which it is very readily distinguished by the
more simple form of its semicells.

Var. excavatum W. & G. S. West. (PL CXXXI,

figs. 4, 5.)

Staurastrum jaculiferum var. excavatum West & G. S. West, Scott. Freshw.
Plankton, I, 1903, p. 544, t. 17, f. 5.

Differs from the type in its broadly obtuse sinus and
elongated cylindrical isthmus.

Length, without spines, 26-27 JJL ; breadth, without
spines, 16-1 9 p. ; length 'of spines 21-29 pi ; breadth of
isthmus 8'5 JJL.

SCOTLAND.- -Plankton of Loch Shin and Loch Ghriama,
Sutherland ! Plankton of Loch near Cearnabahl and
Loch Langabhat, Lewis, and Loch Diracleet, Harris,
Outer Hebrides !

IRELAND. — Rare in plankton of Lough Caragh, Co.
Kerry !

Var. subexcavatum W. & G. S. West. (PI. CXXXI,

fig. 6.)

Staurastrum jaculiferum var. subexcavatum West & G. S. West, Scott
Freshw. Plankton, I, 1903, p. 544, t. 17, f. 6-8.

STAURASTRUM. 19

A form with smaller cells and relatively stouter
spines ; sinus broadly rounded and isthmus cylindrical.

Length, without spines, 25-28 [i ; breadth, without
spines, 16-18 [JL ; length of spines 25-31 [i ; breadth of
isthmus 6*5-7 ^.

SCOTLAND.- -Plankton of Loch Raiar, Loch Morar and
Loch Ghriama, Sutherland !

51. Staurastrum curvatum West.
(PL CXXX, figs. 15, 16.)

Staurastrum curcnium West, Alg. W. Ireland, 1892, p. 172, t. 22, f. 13 ;
West & G. S. West, Scott. Freshw. Plankton, I, p. 543, t. 17, f. 12 ; Further
Contrib. Freshw. Plankton Scott. Lochs, 1905, p. 485 ; Brit. Freshw.
Phytoplankton, etc., 1909, p. 202 ; Wahlburg, Bidr. kanne. Littois-
trask, 1913, p. 48.

Cells of medium size, rather longer than broad, not
including the spines, deeply constricted, sinus nearly
rectangular and obtuse at its apex, semicells lunate,
directed away from each other ; apex of semicell concave,
each angle terminating in a long graceful diverging spine.
Vertical view triangular, lateral margins concave, angles
attenuated, and each one ending in a long spine.
Cell-wall smooth ; chloroplast axile, with a central
pyrenoid and a pair of lobes extending into each angle.

Zygospore unknown.

Length, without spines, 25-32'5 \L ; breadth, without
spines, 20-35 \L ; including spines, 71-75 \L ; length of
spines 20-23 \L ; breadth of isthmus 5-8 pt .

ENGLAND. — Plankton of Buttermere, Ennerdale Water,
Bassenthwaite Water, and Wast Water, Cumberland !
Plankton of Codale Tarn, Grasmere, Stickle Tarn and
Windermere, Westmoreland ! Plankton of Bracebridge
Pool, Sutton Park, War wicks !

WALES.- -In the plankton.

lRELAND.--Derryclare Lough and Ballynahinch, Co.
Galway ! Lough Guitane, Co. Kerry !

SCOTLAND.- -Plankton of Loch Shin and Loch nan
Cuinne, Sutherland ! Loch Luichart and Loch Rosque,
Eoss ! Plankton of Loch na Cloiche Sgoilt, Loch Morar,

20 BRITISH DESMIDIACE.E.

and Loch Shiel, Inverness ! Plankton of Loch Tay,
Perthshire ! ; Loch Doon, Ayrshire ! ; Six lochs in Lewis,
Outer Hebrides ! Plankton of the Shetlands !
Geogr. Distribution. — Norway. Finland.

St. curvatum is most commonly found in the western parts of
the British Isles, and is frequent in the plankton of nearly all
the British lakes, especially those in the area of the older palaeo-
zoic rocks. It is almost entirely a plankton species, but has
occasionally been reported from bogs.

52. Staurastrum megacanthum Lund.
(PL CXXXI, figs. 7, 8.)

Staurastrum megacanthum Lund. Desm. Stiec. 1871. p. 61, t. 4, f . 1 ; Wills in
Midi. Nat. 1881, p. 16, t. 5, f. 7 ; Wolle, Desm. U. S. 1884, p. 121, t. 51,
f. 10-12 ; Cooke, Brit, Desm. 1887, p. 142, t. 49, f . 7 ; De Toni, Syll.
Alg. 1889, p. 1141 ; Roy & Biss. Scott. Desm. 1893, p. 22 ; Schmidle,
Lappm. Susswasseralgen, 1898, p. 50, t. 2, f. 34 (forma) ; West & G. S.
West, Alg. N. Ireland, 1902, p. 44 ; Alga-fl. Yorks, 1902, p. 96.

Cells of medium size, about as long as broad, not
including the spines, or a little shorter, very deeply
constricted, sinus acute- angled, sometimes almost rect-
angular ; semicells triangular, or more often fusiform
in outline, dorsal margin straight or slightly convex,
ventral margin rather more inflated, angles gradually
attenuated, each ending in a strong spine. Vertical view
triangular or quadrangular, sides concave, each angle
produced into a stout spine. Chloroplast axile, with
a central pyrenoid and a pair of lobes projecting into
each angle.

Zygospore unknown.

Length 43-50 p ; breadth, not including the spines,
48-57 pi ; length of spines 11-18 \i ; breadth of isthmus
1 2-14-5 [ju

ENGLAND. • Wastdale, Cumberland ! Plankton of
Stickle Tarn, Westmoreland ! Pilmoor, N. Yorks !
Rice-all Common, E. Yorks !

WALES. — Capel Curig, Carnarvonshire (Cooke & Wills) !
Plankton of the Welsh Lakes !

SCOTLAND. — Aberdeen, Kincardine, Perth and Argyle
(Roy & Biss.). Loch Ghriama, Sutherland ! Loch

STAURASTRUM. 21

Shiel, Inverness ! Loch Brandy (at 2080 ft.), Clova,

Forfar ! Loch Shubhaill and in 5 other lochs in Lewis,
Outer Hebrides !

IRELAND. --In lakes, Clifden to Roundstone, Bally-
nahinch, and rare in the plankton, Galway ! Dublin
and Wicklow (Arch.). Lough Fea, Londonderry !

Geogr. Distribution. — Switzerland. Norway. Sweden.
Finland. Faeroes. Iceland. India. United States.
N.W. Canada. Patagonia.

This species bears a superficial resemblance to St. mucronatum,
but differs in its larger size and more angular semicells. It is
more abundant in plankton than in other situations.

Var. scoticum W. & G. S. West. (PL CXXXI, figs.

9, 10.)

? Staurastntni meyacanthmn forma Borge in Algol. Xotiser 1897, p. 213,

t. 3, f. 7.
St. megacanthuni var. scoticum West & G. S. West, Scott. Fresh\v. Plankton,.

I, 1903, p. 544, t. 16, f. 8 ; Further Contrib. Plankt. Scott. Lochs, 1905,

p. 485.

Apical margin of semicell straight or slightly concave ;
sinus a little more widely open ; spines relatively longer,
and slightly diverging.

Length, without spines, 35-44 a ; breadth, without
spines, 38-51 \i ; including spines 79-1 \\\L ; length of
spines 19-34fj, ; breadth of isthmus 10'5 \L.

SCOTLAND.- -Plankton of Loch Shin, Loch nan Cuinne
and Loch Ghriama, Sutherland ! Mull (Borge). Loch
Doon, Ayr ! Loch Langabhat, Lewis, and Loch Laxa-
dale, Harris, Outer Hebrides !

Geogr. Distribution. — Scandinavia. Canada.

This variety is readily distinguished from the typical form of
St. megacanthum by its slightly concave apex and strong, slightly
diverging spines. [In the opinion of the writer this Desmid
bears a strong resemblance to St. curvatum West, and might well
be placed as a form of this species rather than with St. mega-
Cftnthum. In deference to Professor West, however, it has been
retained in the position originally assigned to it.]

22 BRITISH DESMIDIACE^E.

53. Staurastrum aristiferum Ralfs.
(PI. CXXXII, figs. 10, 11.)

Staurastrum aristiferum Ralfs, Brit. Desm. 1848, p. 123, t. 21, f. 2 ; Arch,
in Pritch. Infus. 1861, p. 737 ; Rabenh. Flor. Europ. Alg. 1868, p. 204 ;
Wood, Freshw. Alg. N. Amer. 1873, p. 149 ; Kirchn. Alg. Schles. 1878,
p. 169 ; Turn. Alg. Strensall Common, 1883, f. 6 ; Wolle, Desm. U. S.
1884, p. 122, t. 40, f. 15, 16 ; Cooke, Brit. Desm. 1887, p. 141, t. 49, f. 6 ;
De Toni, Syll. Alg. 1889, p. 1141 ; Roy & Biss. Scott. Desm. 1894, p. 17 ;
Cornere, Desm. de France, 1901, p. 163, t. 13, f. 15 ; West & G. S. West,
Alga-fl. Yorks, 1902, p. 96 ; Cushrnan, in Bull. Torr. Bot. Club, 1907,
p. 614 ; West & G. S. West, Brit. Freshw. Phytoplankton, 1909, p. 203.

Cells small, a little longer than broad, not including
the spines, very deeply constricted, sinus acute, opening
widely, with a small incision at its apex ; semicells
triangular in outline, the central part somewhat tumid,
angles rather inflated and produced obliquely upwards,
ending in a long spine ; apex of semicell truncate or
slightly inflated in the middle ; lateral margins with
two slight undulations. Vertical view usually quad-
rangular, rarely triangular, lateral margins in the 4-
angled specimen strongly concave, in 3-angled specimens
convex in the middle, angles projecting and ending in
a long spine.

Zygospore unknown.

Length, without spines, 26-30 [JL ; breadth, without
spines, 24-27 \L ; breadth of isthmus 6-7 (ji ; length of
spines 14-19 pi.

ENGLAND. — Brother's Water, Westmoreland ! Mickle
Fell ! and Strensall Common (W. B. Turn.), N. Yorks.

WALES. — Capel Curig ! (Cooke & Wills] and Llyn-y-
cwm-ffynon, Carnarvonshire ! Dolgelly, Merioneth (Ralfs).

SCOTLAND.— Inverness, Aberdeen, Kincardine, Perth
and Dumbarton (Roy & Biss.). Rhiconich, Suther-
land !

IRELAND. — Achill Island, Mayo ! Derryclare Lough
and Kylemore, Co. Gal way !

Geogr. Distribution.- -France. Germany. Austria.
Norway. Sweden. India. Australia. United States.
Brazil.

STAURASTRUM. 23

Var. protuberans W. & G. S. West, (PL CXXXII,

fig. 12.)

Staurastrum aristiferum var. protuberans West & G. S. West, Scott. Freshw.
Plankton, I, 1903, p. 544, t. 14, f. 5.

Apex of semicell strongly convex in the middle
portion ; vertical view triangular with the lateral margins
verv convex in the middle.

«/

Length, without spines, 23-27 \L ; breadth, without
spines, 24-27 \L ; length of spines 13'5-17 \L ; breadth of
isthmus 9*7 JJL.

SCOTLAND.- -Plankton of Loch nan Eun, N. Uist,
Outer Hebrides !

54. Staurastrum cuspidatum Breb.
(PL CXXXII, figs. 13-15.)

tricnxp'ulttta Breb. Alg. Falaise, 1835, p. 57, t. 8.
/>'. cuspidala Bivb. in Clieval. mirrnsr. ct usa'_rc, Is.'J'.i. p. '2"! "2.
xt'tiirastrum cumpiil'ifntti Breb. in Alenegh. Synops. Desm. 1840, p. '2-('< ;

Ralfs, Brit. Desm. 1848, p. 122, t. 22, f. 1, anil t. 33, f. 10 : Arch, in Pritch.

Infus. 1861, p. 737, t. 1, f. 31-34 ; Rabenh. Krypt. Fl. Sachs. 1863, p. 189 ;

Wittr. Gotl. f)l. sotv. 1872, p. 54 ; Delp. iVsm. Subalp. 1877, p. 136, t.

10, f. 26-33 ; Kirchn. Alg. Sdiles. 1878, p. 169; Wolle, Desm. U. S. 1884,

p. 123, t. 40, f. 23-25 ; Cooke, Brit. Desm. 1887, p. 141, t. 49, f. 5 ; Hansg.

Prodr. Algenfl. Bohm. 1888, p. 211 ; De Toni, Syll. Al.-r. 1889, p. 1140 ;

Pvoy & \>\«. Smtt. Dostn. 1S94, p. 19; Schmidle, Lappm. Siisswasser-

algen, 1898, p. 49 : ComtVe, Desm. de France, 1901, p. 163, t. 13, f. 24 ;

•Schroder, Gallertbildung Alg. 1902, p. 168, t. 7, f. 15 ; Wot & G. S. West,

Alga-fl. Yorks. 1902, p. 97 : Alg. X. Ireland, 1902, p. 44 : Freshw. Alg.

Orkneys and Shetlands, 1905, p. 24; Phytoplankton Engl. Lake Distr.

1909, p. 289 ; Hustedt, Desm. Bacill. aus Tirol, 1911, p. 339.
Phycastrum cuspidatum Kiitz. Phyc. Germ. 1845, p. 138 ; Spec. Alg. 1849,

p. 179.
Ph. spinulosum Xag. Gatt. einz. Alg. 1849, p. 126, t. SA, f. 2.

Cells small, about as long as broad, or a little longer,
not including the spines, very deeply and broadly con-
stricted, with a long cylindrical sinus about as long as
a single semicell, sinus broad and obtuse, widening out-
wards ; semicells fusiform, ventral margin more convex
than the dorsal, lateral angles terminating in a stout
spine, either parallel or converging. Vertical view
usually triangular, rarely quadrangular, sides concave,
angles inflated, each with a spine.

24 BRITISH DESMIDIACE^:.

Zygospore spherical, with a limited number of long
stout spines, swollen at the base.

Length, without spines, 20-31 JJL ; breadth, without
spines, 18-28(jt ; breadth of isthmus 5-7 [i ; length of
spines 5-12{ji; diam. zygosp., without spines, 25 (JL ;
including spines 55 [z.

ENGLAND. - - Cumberland ! Westmoreland (Biss.)»
Lancashire ! W., N., and E. Yorks ! Essex ! Oxford-
shire ! Plankton of Bracebridge Pool, Button Park,
Warwicks! Berks (Griffiths). Surrey! Kent! Hants-
(Rolfs] ; zygospores from New Forest ! Devonshire
(Harris) ! Cornwall !

WALES. — Capel Curig (Cooke & Wills) ! Bettws-y-coed
and Glyder Fawr (Roy), Dolbadarn Castle and Llyn
Ogwen, Carnarvonshire ! Ffestiniog, Merioneth !

SCOTLAND.- -Ross, Inverness, Banff, Aberdeen, Kin-
cardine, Forfar, Perth and Argyle (Roy & Biss.). Mull
(Borge). Orkneys and Shetlands !

IRELAND.- -Donegal ! Mayo ! Galway ! Kerry I
Plankton of Lough Neagh ! Dublin and Wicklow (Arch . ) .

Geogr. Distribution.- -France. Germany. Switzerland.
Austria and Galicia. Hungary. Roumania. Italy.
Norway. Sweden. Denmark. Bornholm. Finland.
Poland. N. and S. Russia. Faeroes. Greenland.
Siberia. Japan. Ceylon. Burma. Australia. New
Zealand. Abyssinia. Central Africa. Nova Scotia.
United States. Canada. Brazil.

St. cuspidatum is an extremely common and very widely dis-
tributed species, and its elongated isthmus is one of its most
characteristic features. The spines usually converge slightly
towards those of the other semicell.

Var. maximum West, (PL CXXXII, figs. 18, 19.)

Staurastrum cuspidatuni var. maximum West, Add. Alg. W. Yorks. II,
1891, p. 247 ; Alg. Engl. Lake Distr. 1892, p. 18 ; West & G. S. West,
Alg. S. England, 1897, p. 492 ; Schmidle, Lappmark Susswasseralgen,
1898, p. 49, t. 2, f. 33 ; West & G. S. West, Alga-fl. Yorks. 1902, p. 97 ;
Scott. Freshw. Plankton, 1, 1903, p. 545, 1. 17, f. 13 ; Freshw. Alg. Orkneys
and Shetlands, 1905, p. 24 ; Further Contrib. Freshw. Plankton Scott.
Lochs, 1905, p. 486, t, 1, 5 ; Period. Phytoplankton Brit. Lakes, 1912,
p. 414.

STAUEASTRUM. 25

8t. cuspidatum Borge in Botan. Notiser, 1897, p. 213.

St. cuspidatum var. longispimun Lemm. Beitr. Kenntnis Planktonalg.

1898, p. 153.
St. Daaei Huitfeldt-Kaas, Plankton Norske Vande, 1906, pp. 55 and 155,

t. 2, f. 30, 31.

Cells much larger and isthmus broader than in the
type, spines very long and stout, parallel or diverging,
sometimes curved. Vertical view triangular, sides only
slightly concave or nearly straight.

Length, without spines, 27-43 \L ; breadth, without
spines, 24-30 u. ; breadth of isthmus 4-6 '5 ^ ; length of
spines 10-18 pi.

ENGLAND. - Plankton of Buttermere, Crummock
Water, Bassenthwaite Water, and Wast Water, Cumber-
land ! Plankton of Brother's Water, Ullswater, C4ras-
mere and Windermere, Westmoreland ! Malham Tarn,
W. Yorks ! Epping Forest, Essex !

WALES.- -In the plankton.

SCOTLAND. - Rhiconich, Sutherland ! Common in
the plankton of Ross, Inverness, Perth, Lewis and Harris,
Outer Hebrides, and the Shetlands !

IRELAND.- -Plankton of Mayo and Kerry! Plank-
ton of Lough Xeagh !

Geogr. Distribution. — Germany. Scandinavia. Fin-
mark. Paraguay.

This large variety with its strong spines is a very common
plankton form. The spines are variable in their inflexion, being
usually curved slightly outwards, or sometimes parallel. The
forms described by Borge from the plankton of Mull (in ' Botan.
Notiser,' 1897, p. 213) probably belong to this variety.

«

Var. divergens Nordst. (PL CXXXII, figs. 16, 17.)

Staurastrum cuspidatum var. divergens Nordst. Desm. Brasil, 1870, p. 225,
t, 4, f. 49 ; Gutw. Flor. Glonow Okolic Lwowa, 1891, p. 65 ; West, Freshw.
Alg. W. Ireland, 1892, p. 171 ; Roy & Biss. Scott. Desm. 1894, p. 19 ;
West & G. S. West, New and Int. Freshw. Alg. 1896, p. 157, t, 4, f. 52 ;
Alg. S. England, 1897, p. 492 ; Alga-fl. Yorks, 1902, p. 97.

Cells rather smaller than in the type, spines con-
spicuously divergent ; isthmus variable, elongated or
sometimes very short.

2(3 BRITISH DESMIDIACE^:.

Zygospore globose, with a number of prominent
mamillse, each mamilla provided with a single short
spine.

Length, without spines, 23-25 [JL ; breadth, without
spines, 21-23*3 (JL ; breadth of isthmus 6'6 ^ ; length of
spines 5-10 pi; diam. zygosp., without mamillse and
spines, 23*5-25 pt ; with mamillae and spines 37-41 p.

ENGLAND.- -Whernside, W. Yorks ! Keston Common,
Kent (with zygospores) !

SCOTLAND.- -Not uncommon (Roy & Biss.). Plank-
ton of Loch Bairness, Inverness !

IRELAND. - -Ballynahinch and Glendalough, Co. Gal-
way ! Adrigole, Co. Cork !

Geogr. Distribution. — Germany. Scandinavia. Para-
guay.

Var. coronulatum Gutw. (PI. CXXXIII, fig. 1.)

.S7. cuspidatum var. coronulatiun Gutw. Wahr. d. Prioritat, 1890, p. 71 ;
Flor. Glon. Okolic Lwowa, 1891, p. 66, t. 3, f. 11 ; Roy & Biss. Scot.
Desm. 1894, p. 19.

Angles of the semicell provided with a circle of tiny
verrucse just beneath the point of insertion of the spines.

Length 26 \L ; breadth, with spines, 36 \i ; breadth of
isthmus 5-6 \i .

SCOTLAND.- -Birsemore Loch, Aberdeen (Roy d Biss.).

Geogr. Distribution. — Galicia in Austria. Norway.

It is perhaps worth noting that Schroder (' Gallertb. Alg.'
1902, p. 168, t. 7, f. 15) figures a circle of secreting pores in
exactly the same position as the granules of Gutwinski's
.var. coronulatum. Possibly the supposed granules round the
angles in this variety are merely the hardened heads of the
gelatinous pore-threads, which, in so many Desmids, have fre-
quently been mistaken for granules.

55. Staurastrum pseudocuspidatum Roy & Biss.

(PL CXXXIII, figs. 2, 3.)

Staurastrum pseudocuspidatum Roy & Biss. Jap. Desm. 1886, p. 237, t. 2(38,
f. 3 ; De Toni, Syll. Alg. 1889, p". 1146 ; West, Alg. N. Wales, 1890, p. 10 ;
West & G. S. West. Alg. Madag. 1895, p. 73, t. 8, f. 44.

STAURASTRUM. 27

Cells small, about 1| times longer than broad, deeply
constricted, sinus obtuse, nearly semicircular ; semicells
relatively more broadly oval than in St. cuspidatum,
each angle terminated by a short spine. End view tri-
angular, sides concave, angles slightly inflated, and ter-
minated by a short spine. Cell-wall minutely punctate.

Zygospore unknown.

Length, without spines, 20-35 pt ; breadth, without
spines, 14-27 [j. ; breadth of isthmus, 4-7 fji ; length of
spines, 4-6 \i.

WALES. — Capel Curig, Carnarvonshire !

Geogr. Distribution. — Japan. Madagascar.

This species is distinguished from the preceding one by its
relatively stouter and more broadly oval semicells. The spines
are usually parallel, or sometimes very slightly incurved or di-

vergent.

56. Staurastrum leptodermum Lund.
(PL CXXXII, fig. 20.)

Staurastrum leptodentnutt Lund. Desm. Suec. 1871, p. 58, t. 3, f. 20; De
Toni, Syll. Alg. 1889, p. 1144 ; Roy & Biss. Scott, Desm. 1894, p. 22 ;
West & G. S. West, Wehv. Afric. Freshw. Alg. 1897, p. 45 (forma) ;
Liitkem. Desm. Central China, 1900, p. 123, t, 0, f. 30, 31 (forma).

Cells of medium size, about as long as broad, deeply
constricted, sinus broad and subrectangular ; semicells
cuneate, widening considerably towards the apex, sides
nearly straight, but with two obscure undulations, apex
slightly tumid in the middle, angles terminating in a
minute spine directed c L liquely upwards. Vertical
view triangular, sides straight, angles acute with a
short spine. Cell-wall very thin ; chloroplast axile.

Zygospore unknown.

Length 58-60 p. ; breadth, without spines, = length ;
breadth, with spines, 61-64 ^ ; breadth of isthmus 22 pi.

SCOTLAND. — Slewdrum, Aberdeen (Roy d' Biss.).

Geogr. Distribution. — Sweden. Finland. Central
China. Bengal.

28 BRITISH DESMIDIACE^E.

57. Staurastrum Ungeri Reinsch.'
(PL CXXXIII, fig. 5.)

Staurastrum Ungeri Reinsch, Spec. Gen. Alg. 1867, p. 24, t. 24 B, I, f. 1-6 ;

De Toni, Syll. Alg. 1889, p. 1152 ; Roy & Biss. Scott. Desm. 1894, p. 26
Didymidium (Staurastrum) Ungeri Reinsch, Algenfl. Frank. 1867, p. 174,.

t. 11, f. 3.
Staurastrum acanthophorum West & G. S. West, Alg. Madag. 1895, p. 72,.

t. 8, f. 10 (var.).

Cells small, about as long as broad, deeply con-
stricted, isthmus one- third or more the diameter of
the cell, sinus acute-angled ; semicells elliptical, dorsal
and ventral margins almost equally convex, lateral
angles ending in a stout spine, in length one-third or
one-fourth the diameter of the cell. Vertical view tri-
angular or quadrangular, lateral margins straight or
slightly concave, angles obtusely rounded, each with a
stout spine. Cell- wall provided with numerous short
conical spines, irregularly scattered, and about one-
third or one-fourth the length of the larger angular
spines.

Zygospore unknown.

Length = breadth = 27 or 28 \L ; length of angular
spines 8 \L .

SCOTLAND.- -Loch Ruthven, Inverness; old channel
of Dee, below Aboyne, Aberdeen ; Keiloch, Kincardine
(Roy & Biss.).

Geogr. Distribution. — Germany. Switzerland (var.).
Madagascar (var.).

58. Staurastrum tunguscanum Boldt.
(PL CXXXIII, fig. 4.)

Staurastrum tunguscanum Boldt, Sibir. Chlorophy. 1885, p. 114, t. 5, f. 22 ;
De Toni, Syll. Alg. 1889, p. 1146; Gutw. Flor. Glon. Okolic Lwowa,
1891, p. 66. t. 3, f. 12 (forma) ; Borge, Siissw. Chlor. Archang. 1894,
p. 37 ; West & G. S. West, Alg. S. England, 1897, p. 493.

Cells small, slightly longer than broad, deeply con-
stricted ; sinus acute-angled, opening widely ; semicells
subtriangular, directed away from each other, lateral

STAURASTRUM. 29

margins convex, apex of semicells truncate or slightly
retuse, angles produced to form a colourless recurved
spine ; cell-wall finely granulate-denticulate. Vertical
view triangular, angles slightly inflated and ending in
a short straight spine ; lateral margins gently concave.

Zygospore unknown.

Length 19-30fji ; breadth, not including spines, about
19-24fjt; length of spines 6 JJL ; breadth of isthmus
7-10 p.

ENGLAND.— Puttenham Common. Surrey !

s t

Geogr. Distribution. — Germany. Galicia in Austria.
Sweden. N. Russia.

St. tunguscanum is closely allied to St. granulosum (Ehr.)
Ealfs and St. lunatum Ralfs. It differs from both these specie
in its distinctly truncate or retuse apex, and its angular spines
are also very much stouter than the delicate spines of St. granu-
losum.

59. Staurastrum lunatum Ealfs.
(PL CXXXIII, figs. 17-19.)

Staurastrum lunatum Ralfs, Brit. Desm. 1848, p. 124. t. -'54, f. 12 ; Arch, in
Priteh. Inf. 1861, p. 738 ; Rabenh. Krypt. F!. Sachs. 1S63, p. 193 ; Flor.
Europ. Alg. 1868, p. 221 ; Cooke, Brit. Desm. 1887, p. 143, t, 50, f. 5;
De Toni, Syll. Alg. 1889, p. 1146; Racib. Desm. Xmve, 1889, p. 28;
West, Add.' Alg. W. Yorks. II, 1891, p. 247 ; Alir. \V. Ireland, 1892,
p. 173 ; Roy & Biss. Scott. Desm. 1894, p. 22 : West & G. 8. West, Alg.
S. England,' 1897, p. 493; Schroder, Gallertbildimu Ah,'. 1902, p. 168,
t. 7, f. 16; Teodoresco, Mater, flor. alg. Rouman. l!i<>7. p. 184.

Cells rather under medium size, about as long as
broad or a little shorter, not counting the spines, deeply
constricted, sinus acute and widening outwards ; semi-
cells semicircular or almost lunate, directed away from
each other, dorsal margin very slightly convex, ventral
margin very tumid, upper angles of semicell obtuse,
and ending in a short stout spine which projects obliquely
outwards. Cell- wall uniformly rough with tiny granules
arranged in concentric rows round the angles. Vertical
view triangular, sides concave, angles terminating in a
short spine, granules becoming smaller towards the

30 BRITISH DESMIDIACE^E.

centre, apex of semicell almost smooth. Chloroplast
axile with a central pyrenoid in each semicell.

Zygospore unknown.

Length, without spines, 35-39 y. ; breadth, without
spines, 35-43 y. ; breadth of isthmus 10-13 (JL ; length of
spines 3 '5-1 2 pt.

ENGLAND. — Cumberland ! Westmoreland ! W., N.,
and E. Yorks ! Essex ! Oxford ! Hants ! Warwicks !
Dartmoor, Devon (Harris). Cornwall (Rolfs}.

SCOTLAND.- -Near Tain, Ross ; near Brin, Inverness ;
near Alford, S. of Birsemore, Dalbagie, Aberdeen (Roy
& Biss.). Craig an Lochan, Perth ! Mull in Argyle
(0. Borge).

IRELAND. --Foxford, Co. Mayo! Derryclare Lough
and Oorid Lough, Co. Galway ! Near L. Brin, Co.
Kerry.

Geogr. Distribution.- -France. Germany. Roumania.
Norway. Finland. Sweden. Faeroes. Greenland.
Siberia. Azores. United States and Alaska.

The granules in the vicinity of the angles often tend to
become developed into small spicules in this species, so that
the angular spines may seem to be duplicated.

Var. planctonicum W. & G. S. West. (PL CXXXIII,

figs. 20-22.)

Staurastrum lunatum var. planctonicum West & G. S. West, Scott. Freslnv.
Plankton, I, 1903, p. 546, t. 16, f. 11, 12; Freshw. Alg. Orkneys and
Shetlands, 1905, p. 24 ; Comp. Study Plankton Irish Lakes, 1906, p. 103 ;
Brit. Freshw. Phytoplankton, 1909, p. 174.

Cells relatively broader and attaining a larger size
than in the type, angles of semicells more acute and
ending in a shorter spine. Vertical view triangular,
angles gradually tapering to a short spine, lateral mar-
gins broadly retuse.

Length 40-44 \L ; breadth, without spines, 42-50 \L ;
breadth of isthmus 14'5-16 fi ; length of spines 3-5'5 \L.

ENGLAND.- -Plankton of Crummock Water, Ennerdale
Water, Bassenthwaite Water and Wast Water, Cumber-

STAURASTRUM. 31

land ! Haves Water, Red Tarn, Grasmere and Winder-

9J

mere, Westmoreland !

WALES.- -In the plankton !

SCOTLAND.- -X. of Stornoway, Lewis ! General in the
plankton of many lochs in the mainland and Outer
Hebrides ! Plankton of Shetlands !

IRELAND.- -Plankton of Gahvay and Kerry !

Geocjr. Distribution.- -Norway. Finmark. Finland.
Eussian Lapland. X.W. Canada.

This variety is very frequent in plankton, and sometimes
occurs in abundance. It is distinguished from typical St. lunatum
by its more angular semicells, in which the angles are more pro-
duced, and end in much smaller spines. There is no very obvious*
constriction at the base of the spines. The entire cell is finely
granulated, the granules being very acute and arranged in con-
centric series round the angles. It is similar to St. lit t/« turn L
alpestris Schmidle (in ' (Est. Bot. Zeitschr.' 1895, p. 24, t. 16,
f . 27), but differs in the more attenuated angles of the semicells
which run directly into the spines, whilst its granulation is also
more uniform.

CO. Staurastrum cornutum Arch.
(PL CXXXIII, fig. 16.)

Staurastrum cornutum Arch, in Ann. Mag. Nat. Hist. 1881, p. 232 ; Cooker
Brit, Desm. 1887, p. 190 ; De Toni, Syll. Alg. 1889, p. 1175 ; Roy & Biss.
Scott, Desm. 1893, p. 180, t, 3, f. 5; Gronblad, Desm. Keuru, 1920, p. 60,
t. 2, f. 27, 28, t, 3, f. 54, 55.

Small ; length and breadth equal ; semicells oval,
diverging widely from the isthmus, which is broad ;
sides with one simple or deeply cleft stout spine ; end
with about six small emarginate spines, and two rows
of similar spines within the margin ; end view triangular,
with a stout spine at each angle, and about four small
emarginate spines on the margin of the straight sides,
and one row of similar spines within the margin (Roy}.

Zygospore unknown.

Length and breadth, without side spines, 27 p ;
isthmus 1 1 [JL ; length of spine 9 y. .

32 BRITISH DESMIDIACE^:.

SCOTLAND.- -Logie, Coldstone and Blairglas, Aber-
deen ; Glen Coe, Argyle (Roy & Biss.).
IRELAND. — Connemara (Arch.).
Geogr. Distribution.- -Finland.

Until quite recently this species had never been seen since
it was discovered by Archer except by Roy and Bissett.

The latter investigators remark that it is "extremely rare,"
and that ' its nearest ally is St. maamense Arch.," but that " the
stout spines sufficiently distinguish it." Gronblad now records
it from Finland.

61. Staurastrum Gatniense W. & G. S. West.
(PL CXXXV, figs. 14, 15.)

St. Gatniense West & G. S. West, Alg. N. Ireland, 1902, p. 48, t. 2, f. 35.

Cells small, slightly broader than long, not counting
the spines, very deeply constricted, sinus open, narrow,
and finally dilated at the extremity ; semicells elliptic-
trapeziform, apex broad and slightly undulate, basal
angles provided with a short stout converging spine,
lateral margins slightly convex, and with two distant
spines. Vertical view triangular, angles tumid and with
a ring of denticulabions, sides smooth and very slightly
concave.

Zygospore unknown.

Length 27 '5^ ; breadth, without spines, 29 y. ; with
spines, 33*5 ^ ; breadth of isthmus 8 ji.

IRELAND. --Lough Gatny, Co. Donegal !

This peculiar Staurastrum is not very closely allied to any
other British species of the genus.

62. Staurastrum bifidum (Ehr.) Breb.
(PL CXXXIV, fig. 4.)

Desmidium bidens Ehr. Inf. 1838, p. 141, t. 10, f. 11.

Phycastrum bifidum Kutz. Phyc. Germ. 1845, p. 138 ; Spec. Alg. 1S49,

p. 180.
Staurastrum bifidum (Ehr.) Breb. in Ralfs, Brit. Desm. 1848, p. 215; Arch.

in Pritch. Inf. 1861, p. 741 ; Rabenh. Krypt. El. Sachs. 1863, p. 192 ;

STAURASTRUM. 33

Flor. Europ. Alg. 1868, p. 205 ; Lund. Desm. Suec. 1871, p. 62, t. 4, f . 2 ;
Kirchn. Alg. Schles. 1878, p. 169 ; Cooke, Brit. Desm. 1887, p. 163, t. 57,
f. 3 ; Hansg. Prodr. Algenfl. Bohm. 1888, p. 212 ; De Toni, Syll. Alg.
1889, p. 1198 ; Roy & Biss. Scott. Desm. 1893, p. 17 ; Liitkem. Desm.
Central China, 1900, p. 123 ; West & G. S. West, Freshw. Chlorophy.
Koh Chang. 1901, p. 92 ; Freshw. Alg. Ceylon, 1902, p. 176 ; Freshw.
Alg. Burma, 1907, p. 212, t. 16, f. 7.
Phycastrum (Stenactinium) bifidum Nag. Gatt. einz. Alg. 1849, p. 128.

Cells rather under medium size, about as lono' as

7 O

broad, not counting the spines; constriction fairly deep,
sinus subrectangular ; semicells subelliptical or subtri-
angular, dorsal margin slightly convex, ventral margin
very tumid, provided at each angle with two stout
spines, which usually lie in the same horizontal plane
and project obliquely downwards ; cell- wall smooth.
Vertical view triangular, sides straight or slightly con-
cave, angles broad and bifid, lobes separated by a broad
concavity, and each one tipped with a sharp spine.

Zygospore unknown.

Length 28-33 \L ; breadth, without spines, 29-33 JJL ;
with spines, 48-56(1 ; breadth of isthmus 11 "5-1 4 JJL.

ENGLAND. — Cornwall (Marquand) .

SCOTLAND.- -Poole we, Eoss (Roy & Biss.).

(reoyr. Distribution.- -France. Germany. Hungary.
Italy. Sweden. Finland. Poland. N. Russia. Central

«/

China. Japan. India. Ceylon. Burma. Siam. Java.

63. Staurastrum longispinum (Bail.) Arch.
(PL CXXXIV, fig. 1.)

Didymocladon / longispinum Bail. Microscop. Observ. 1851, p. 36, t. 1, f. 17.
Staurastrum longispinum Arch, in Pritch. Inf. 1861, p. 743 ; Rabenh. Flor.

Europ. Alg. 1868, p. 221 ; Wood, Freshw. Alg. N. Amer. 1874, p. 148 ;

Wolle, Desm. U.S. p. 145, t. 41, f. 7 ; Lagerh. Bidr. Amerik. Desm.-fl.

1885, p. 249, t. 27, f. 28 ; De Toni, Syll. Alg. 1889, p. 1199 ; West, Alg.

W. Ireland, 1892, p. 180 ; West & G. S. West", Alg. N. Ireland, 1902, p. 45 ;

Scott. Freshw. Plankton, I, 1903, p. 545 ; Brit. Freshw. Phytoplankton,

1909, p. 174.
St. (Schizastrum) longispinum Turn. Freshw. Alg. E.- India, 1893, p. 132,

t. 23, f. 12.

Cells very large, deeply constricted, sinus acute,
opening widely ; semicells subelliptical or subtriangular,
dorsal margin slightly convex, ventral margin more

VOL. v. 3

34 BRITISH

strongly so, angles very slightly produced (almost
imperceptibly) and provided with two stout spines of
varying length, projecting obliquely outwards and lying
in the same vertical plane, the two spines either parallel
or converging. Vertical view triangular, sides slightly
concave and angles broadly rounded. Cell- wall very
thick and distinctly punctate. Chloroplasts numerous,
in the form of parietal bands running longitudinally,
with numerous scattered pyrenoids.

Zygospore unknown.

Length 90-1 20 ^ ; breadth, without spines, 73-1 00 ui ;
breadth of isthmus 36-41 ^ ; length of spines 9'o-32'5 pi.

ENGLAND.- -Plankton of Ennerdale Water, Cumber-
land, and Grasmere, Westmoreland !

WALES. — Capel Curig ! (Cooke & Witts) and Llyn-y-
cwm-ffynon, Carnarvonshire !

SCOTLAND.- -Plankton of Loch Shin, and Rhiconich,
Sutherland ! Plankton of Loch Shiel, Inverness ! Plank-
ton of Lochs Fadaghoda and Stranabhat, Lewis, and
Loch nan Eun, N. Uist, Outer Hebrides !

IRELAND. — Near Lough Magrath, Donegal ! Lough
Aunierin, Co. Galway ! Plankton of Lough Currane,
Kerry ! Adrigole, Co. Cork !

Geoyr. Distribution. — Norway. Sweden. India. Aus-
tralia. United States.

St. longispinum is a large and characteristic species which
could not easily be confused with any other. It is very
abundant in plankton. The spines are variable in length,
and all stages occur between the typical long-spined form and
the form known as var. bidentatum, in which they are very re-
duced.

Var. bidentatum (Wittr.) West. (PI. CXXXIV, figs. 2, 3.)

St. bidentatum Wittr. Skand Desm. 1869, p. 16, f. 7.
St. (Pleurenterium) longispinum Lund. Desm. Suec. 1871, p. 73, t. 5, f. 1.
N/. longispinum Cooke, Brit. Desm. 1887, p. 164, t. 56, f. 1.
tit. longispinum, var. bidentatumWeat & G. S. West, Scott. Freshw. Plankt. I,
1903, p. 546 ; Cushman in Rhodora, 1905, vol. 7, p. 263, t. 64, f. 13.

Similar to the type in every way except that the spines

STAURASTRUM. 35

are very mucli reduced and the apex of the semicell is
often nob so convex.

Length 80-90 JJL ; breadth, without spines, 75-85 y. ;
length of spines 7-10 p ; breadth of isthmus 30-35 [/..

ENGLAND.- -Plankton of Ennerdale Water, Cumber-
land !

WALES.- -In the plankton !

SCOTLAND. — Glen Coe, Argyle, 1878 (Roy <£ Biss.).
Khiconich, Sutherland ! Plankton of Lochs Fadaghoda
and an Sgath, Lewis, Loch Diracleet, Harris, and Loch
nan Etm, N. LTist, Outer Hebrides !

Geogr. Distribution. — Switzerland. Sweden. United
States.

64. Staurastrum Brasiliense Nordst.
(PL CXXXY, fig. 11.)

m Brasiliense Xordst. Desm. Brasil. 1869, p. 227, t. 4, f. 39 ;
Wolle, Freshw. Alg. U.S. 1887, p. 46, t. 60, f. 39, 40 ; De Toni, Syll. Alg.
1889, p. 1200 ; Cushraan in lihodora, vol. 7, 1905, p. 262.

Cells large, about Ij times longer than broad, deeply
constricted with a broad sinus ; semicells shortlv

«/

cuneate, broadening towards the apex which is truncate
or slightly retuse, lateral margins concave ; upper
angles each terminating in 3 stout diverging spines ;
cell- wall punctate ; isthmus about one-half the diameter
of the cell. Vertical view 4- (-5-) angled, angles termi-
nating in 3 diverging spines (on one occasion 4 have
been observed) ; lateral margins concave.

Zygospore unknown.

Length, not including the spines; 43-51 JJL ; with
spines, 56-77 [i ; breadth, not including the spines,
25-37 (JL ; with spines 65-99 JJL.

Geogr. Distribution.- -IN oiw&y. Abyssinia. United
States. Brazil.

Var. Lundellii W. & G. S. West. (PI. CXXXV,

figs. 12, 13.)

St. Brasiliense forma Lund. Desm. Suec. 1871, p. 73, t. 5, f. 2 ; Cooke, Brit.
Desm. 1887, p. 165, t. 56, f. 2 ; Wolle, Desm. U. S. 1884, p. 146, t. 48,
f. 1-3.

30 BRITISH DESMIDIACE^:.

N/. lln i .^iliense var. Lundellii West & G. S. West, Some N. Amer. Desm.

1896, p. 259 ; Notes Alg. II, 1900, p. 295 ; Scott. Freshw. Plankt. I,

3903, p. 546; Further Contrib. Freshw. Plankt. Scott. Lochs, 1905,

p. 480.
St. Brasiliense var. Lundellianum Schmidle, Lappmark Siisswasseralgen,

1898, p. 58.

Cells very large, about 1^ times longer than broad,
deeply constricted ; sinus broad, deeply excavated at its
apex; semicells cuneate, sides and apex nearly straight,
upper angles somewhat obliquely truncate, and provided
with 3 stout spines each, 2 of which lie in the same hori-
zontal plane, the third being inserted in a more dorsal
position and at an angle to the others. Vertical view
5-, rarely 6-angled, sides deeply concave, angles broad
and bifid, each lobe attenuated into a stout spine, and
with a third spine at each angle lying between the other
two, inserted on the apex. Chloroplast axile, with
numerous pyrenoids.

Length, without spines, 75-80 \L ; with spines 120-
130(jL ; breadth, without spines, 63-80 [JL ; with spines,
120-140 [JL ; breadth of isthmus 28-34 p ; length of
spines 25-30 JJL.

ENGLAND.- -Plankton of Ennerdale Water, Cumber-
land, and Easedale Tarn, Westmoreland !

WALES. — Capel Curig, Carnarvonshire ! (Cooke &
Wills). In the plankton !

SCOTLAND. — Plankton of Loch Shin, Sutherland ! L.
Shiel, Inverness ! Plankton of Loch Fadaghoda and L.
an Sgath, Lewis, and L. nan Eun, N. Uist, Outer
Hebrides.

IRELAND.- -Foxford, Co. Mayo ! Arderrv Louo-h, and

J «/ o

in the plankton, Galway ! Cloonee Lough and in the
plankton, Kerry !

Geogr. Distribution.- -Norway . Sweden. Finland.
United States. Paraguay.

This beautiful Desmid is a distinctly ' western "* type, and
is more frequent in plankton than in other situations, often
occurring in abundance. With its three stout angular spines
it is quite distinct from any other species. The cell-wall is

* Vide p. 18 supra.

STAURASTRUM. 37

usually of some thickness, and is distinctly punctate. The
spines are hollow only at the extreme base.

65. Staurastrum quadrangulare Breb.
(PL CXXXIV, fig. 5.)

Staurastrum quadrangulare Breb. in Ralfs, Brit. Desm. 1848, p. 128, t. 2:2,
f. 7, t, 34, f. 11 ; Arch, in Pritch. Infus. 1861, p. 741, t. 3, f. 24, 25 ;
Rabenh. Flor. Europ. Alg. 1868, p. 215 ; Kirchn. Alg. Schles. 1878, p. 170 ;
\Volle, Desm. U. S. 1884, p. 145, t. 41, f. 1-4 ; Cooke, Brit, Desm. 1887,
p. 164, t, 55, f. 4 ; De Toni, Syll. Alg. 1889, p. 1199 ; AYest, Alg. Eng.
Lake Distr. 1892, p. 20 ; Roy & Biss. Scott. Desm. 1893, p. 24 ; Eichler,
Mat. Flor. Miedz. 1893, p. 62 ; and 1894, p. 131, t. 4, f. 46 : West & G. 8.
West, Some N. Amer. Desm. 1896, p. 257, t. 16, f. 16, 17 : Gutvr. Wykaz.
Glonow Wadow.-Makow. 1897, p. 161 ; Comere, Desm. de France, 1901,
p. 166, t. 12, f. 23 : Georgev. Desm. Macedonia, 1910, p. 244.

Didymidium Hystrix, A. mi mis, p tetrayonum Reinsch, Algenfl. Frank.
1867, p. 171.

^tnurastrum quadra mjulare f. major Cooke, Brit. Desm. 18S7. ]>. 164; Teo-
doresco, Mater. Flor. alg. Roumania, 1907, p. 186.

Cells small, in general outline subrectangular, sinus
fairly deep and acute, almost linear ; semicells rect-
angular, dorsal margin straight, lateral margins straight
or slightly concave, ventral margin very slightly convex ;
angles of semicells provided typically with 4 spines each,
one pair towards the apex and another at the base;
spines conical and diverging, at times one or other of
them duplicated or wanting. Vertical view typically
4-angled; rarely 3- or 5-angled, sides straight or very
slightly concave, angles broad and very slightly produced,
each bearing two superimposed pairs of spines.

Zygospore unknown.

Length 20-30 JJL ; breadth, including spines, 20-30 JJL ;
breadth of isthmus 8-10 a.

ENGLAND. — Ambleside (Ralfs) and Loughrigg, West-
moreland !

SCOTLAND. --Birsemore Loch, near Dinnet, and Dal-
bagie, Aberdeen (Roy & Biss.). Rhiconich, Sutherland !
Tarbert, Harris !

IRELAND.- -Near Foxford, Co. Mayo! Dublin and
Wicklow (Arch.).

Geoyr. Distribution- -France. Germany. Galicia in

38 BRITISH DESMIDIACE^E.

Austria. Turkey-in-Europe. Norway. Sweden. Born-
holm. Finland. Poland. N. Eussia. Japan. Abyssinia
(var.). Central Africa (var.). West Indies (var.). Brazil.
Argentine (var.).

66. Staurastrum quadrispinatum Turn.
(PL CXXXV, figs. 5-7.)

St. quadrispinatum Turn. Notes Freshw. Alg. 1886, p. 35, t. 1, f. 4 ; Cooker
Brit. Desm. 1887, p. 164, t. 55, f . 5 ; De Toni, Syll. Alg. 1889, p. 1199;
Johnson, Rare Desm. U. S. I, 1894, p. 289 ; West & G. S. West, Some
N. Amer.' Desm. 1896, p. 258, t. 18, f. 17 ; Borge, Nordamerik. Siiss-
wasseralg. 1909, p. 11.

Cells small, li to Ij times longer than broad, not
including the spines, deeply constricted, sinus open and
acute ; semicells elliptic-oblong, broader at the base than
at the apex, often somewhat angular ; apex nearly flat,
ventral margin strongly convex, lateral margins trun-
cate, angles of the semicell provided with 4 stout and
strongly divergent spines, one pair at the upper and lower
extremities of the angle respectively. Vertical view
triangular, sides straight, angles broadly truncate, spines
so divergent as to be almost perpendicular to the lateral
margins, and nearly in a line with the truncate angles.
Cell- wall finely punctate.

Zygospore unknown.

Length, without spines, 33-39 \L ; breadth, without
spines, 26-30*5 [i ; breadth of isthmus 8-10'5 \L ; length
of spines lOfji.

WALES.- -Trelleck Common, Monmouth (Turn.}.

Geogr. Distribution.- -United States.

This species is distinguished from St. quadrangulare Breb. by
its relatively greater length, and its stouter spines, wMchJare
also much more divergent.

67. Staurastrum denticulatum (Nag.) Arch.
(PI. CXXXIII, figs. 13-15.)

Phycastrum (Pachy actinium) denticulatum Nag. Gatt. einz. Alg. 1849, p 128
t. 8, C. f. 3.

STAURASTRUM. 39

Staiirastnim denticulatuin Arch, in Pritch. Inf. 1861, p. 738 ; Rabenh. Flor.

Europ. Alg. 1868, p. 213; Kirchn. Alg. Schles. 1878, p. 169; Hansg..

Prodr. Algenfl. Bohm. 1888, p. 214 ; De Toni, Syll. Alg. 1889, p. 1163 ;

West, Alg. N. Wales, 1890, p. 16, f. 27 ; West & G. S. West, Alg. S.

England, 1897, p. 493 ; Comp. Study Plankton Irish Lakes, 1906, p. 103 :

Gutwin. Flor. Alg. Mont, Tatr. 1909, p. 470.
DidyittitHum (Staurastrum) Tigurinum Reinsch, Algenfl. Frank. 1867, p. 161.

Cells small, about as long as broad, or a little shorter,
deeply constricted, sinus acute-angled, and opening
widely ; semicells subelliptical or fusiform, dorsal margin
slightly convex in the middle, ventral margin strongly
so ; angles of semicell obtuse and tipped by two minute
spines. Cell- wall rough with tiny granules confined to
the region of the angles, and arranged in two or three

o o * o

concentric rings around them. Vertical view triangular,
sides straight or very slightly concave, angles obtusely
rounded.

Zygospore unknown ?

Length 24-35 u. ; breadth 20-40 u. : breadth of isth-
mus 7-1 4 [x.

ENGLAND.- -Plankton of Ennerdale Water and Wast
Water, Cumberland! Red Tarn, Hawes Water and Gras-
mere, Westmoreland ! Epping Forest, Essex ! Worcs !

WALES.- -Ffestiniog, Merioneth ! In the plankton !

IRELAND.- -Minister and Connaught (Adams). Plank-
ton of Mayo and Kerry !

Geogr. Distribution. — Germany. Galicia in Austria.
Spain. Sweden. Denmark. Finland. Poland. N. Russia
Faeroes. Australia. Central Africa. Azores. Colombia,
S. America.

This species is distinguished from St. Avicula Breb. by its
granulation, there being only two or three series of distinct
granules round the angles, and the cells are also proportionately
broader.

The zygospore of this species has not hitherto been figured.
Amongst some unnamed drawings by the late Professor G. S. West
is one. however, which is reproduced on PL CXXXIII, fig. 15.
This drawing had not been named by Professor West, but it evi-
dently belongs either to St. denticulatum or St. Avicula. As far

v O

as the characters can be seen from the empty semicells in their

40 BRITISH DESMIDIACE^.

present position, the writer is inclined to attribute the figure to
St. denticulatuni.

68. Staurastrum Avicula Breb.
(PI. CXXXIII, figs. 8-10 and 12.)

Staimistruin Avicula Breb. in Ralfs, Brit. Desm. 1848, p. 140, t. 23, f. 11 ;
Arch, in Pritch. Infus. 1861, p. 738, t. 3, f. 18, 19 ; Rabenh. Flor. Europ.
Alg. 1868, p. 204 ; Lund. Desm. Suec. 1871, p. 61 : Delp. Desm. sulalp.
1877, p. 165, t. 12, f. 22-29 ; Turn. Alg. Strensall Common, 1883, p. 80,
t, 1, f. 1 ; Wolle, Desm. U. S. 1884, p. 123, t. 40, f. 30-32 ; Cooke, Brit.
Desm. 1887, p. 145, t. 50, f . 9 ; De Toni, Syll. Alg. 1889, p. 1153 ; West,
Ale. W. Ireland, 1892, p. 174; Roy & Biss. Scott, Desm. 1893, p. 17,
t. 3, f. 11 ; West & G. S. West, Alg. S. England, 1897, p. 493 ; G. S. West,
Alga-fl. Camb. 1899, p. 25, t. 396, f. 10 ; West & G. S. West, Alga-fl.
Yorks. 1902, p. 97; Alg. N. Ireland, 1902, p. 46; Borge in Botan.
Notiser 1913, p. 29 ; Gronblad, Desm. Keuru, 1920, p. 57, t. 3, f. 36-38.

Cells small, about as long as broad, deeply constricted,
sinus variable, usually linear for some little distance,
then opening widely ; semicells subelliptical or sub-
triangular, dorsal margin slightly convex, lateral mar-
gins sometimes nearly straight, but often very convex ;
upper angles of semicells furnished with two minute
spines, one placed vertically above the other, the dorsal
one often slightly longer ; cell-wall more or less dis-
tinctly rough with minute granules arranged in con-
centric rows round the angles. Vertical view triangular,
sides concave, angles very obtuse, one spine only being
visible, as a rule, at each angle.

Zygospore not very well known, but according to
Roy, probably globose and furnished with a number of
conical spines, very broad at the base and bifurcate at
the apex.

Length 29-34*5 ^ ; breadth, with spines, 35 u ; breadth
of isthmus 9-1 1 JJL .

ENGLAND.- -Westmoreland ! (Biss.). W., N., and E.
Yorks ! Leicester (Roy). Cambs ! Plankton of Bracebridge
Pool, Warwicks ! Worcs ! Hants ! (Bennett). Devon !
(Harris). Cornwall !

WALES. — Capel Curig (Cooke & Wills) I Llyn Ogwen
and Llyn Bodgynwydd, Carnarvonshire ! Ffestiniog,
Merioneth !

STAURASTEUM. 41

SCOTLAND. — General ! Zygospores from Heughhead,
Kincardine (Roy & Biss.). Rare in the plankton !
IRELAND. — Donegal ! Clare Island. Mavo ! Galwav !

c? t */

Kerry ! Dublin and Wicklow (Arch.). Armagh ! Lon-
donderry ! Plankton of L. Xeagh !

Geoyr. Distribution.- -France. Germany. Switzerland.
Galicia in Austria. Hungary. Servia. Italy. Norway.

f V W

Finmark. Sweden. Finland. Faeroes. Greenland.
Japan. United States and Alaska. Brazil.

St. Avicula is widely distributed, though rarely occurring in
abundance. Its uniform granulation and the pair of minute
spicules at each angle of the broadly ovate semicells distinguish
it. Occasionally one or more of the granules near the angles

»/ O

tend to develop also into short spines.

Var. subarcuatum (Wolle)West. (Pl.CXXXIILng.il.)

rum ji(/]>illn*ti)n Kirchn. Alg. .Schles. 1878, p. 17<>.
St. denticiilntuin Elf. Anteck. Finska Desm. 1881. p. 9. t. 1. t. .~>.
St. subarcuatum Wulle, Desm. U. S. 1884. p. 140. t. 415. t. 1/i, Hi : De Toni,

Syll. Alg. 1889, p. 11 (id.

St. Avicula var. verrucosum West, Alg. W. Irelajul. 181)2, p. 174. t. 23, t'. 2.
St. Avicula var. subarcuatiun \\V>t & ('<. S. \\Vst, Xe\v Brit. Freslnv. Alu.

1894, p. 10 ; Alg. 8. England, 1897, p. 493 ; Alga-n. V.»rks. 1902. p. 98 ;

Alg. X. Ireland, 1902, p.~4l> : Freshw. Alir. nrkney.s and Shet lands, 190.'i,

p. 24: Brit. Freshw. Phytoplankton, 1909. ]>. 17>>.

Semicells more distinctly triangular than in the type,
dorsal margin nearly straight, sinus more open and acute,
angles of cell very slightly produced, membrane dis-
tinctly granulate, granules arranged in concentric rows
round the angles.

Length 22*5-27 ku ; breadth, including spines, 30-37 JJL ;
breadth of isthmus 8 '5-10 JJL.

ENGLAND. — Mossdale Moor and Widdale Fell, W.
Yorks ! Stokesley, X. Yorks ! Epping Forest. Essex !
New Forest, Hants !

WALES. — In the plankton.

SCOTLAND. --Loch Kinnelan, Ross; Tonley Pond,
Aberdeen (Roy d- Biss.). Plankton of Lochs na Cloiche
Sgoiltj Bairness, and na Cliche, Inverness! Plankton of
Lochs Cuthaig, Fadaghoda, Roinebhall, and Stranabhat,

42 BRITISH DESMIDIACE^:.

Lewis, and Loch a Mhorghain, Harris, Outer Hebrides !
Orkneys and Shetlands !

IRELAND.- -Donegal ! Clare Island, Co. Mayo! Gal-
way ! Kerry ! Armagh ! Plankton of (lalway !

Geogr. Distribution. — Germany. Finland. India.
Australia. United States.

This variety seems to differ from typical St. Avicula in the
form of its semicells as well as in its stronger granulation. In
the front view the semicells are more cuneate, with sides and
apex nearly straight, and the angles of the cell are very slightly,
almost imperceptibly, produced. In the vertical view the sides
are more concave than in the type.

69. Staurastrum subcruciatum Cooke & Wills.
(PL CXXXIII, figs. 6, 7.)

Staurastnitii subcruciatum Cooke & Wills in Cooke, Brit. Desm. 1887, p. 148,
t. 51, f. 3 ; De Toni, Syll. Alg. 1889, p. 1158 ; Schmidle, Alg. Geb. Ober-
rheins, 1893, p. 553 ; West & G. S. West, Alga-fl. Yorks. 1902, p. 97.

Cells a little broader than long, deeply constricted, sinus
acute and almost rectangular, opening widely ; semicells
somewhat triangular or lunate, dorsal margin concave,
slightly convex in the middle, ventral margin approxi-
mately semicircular, angles slightly produced obliquely
upwards and tipped by two diverging spines which lie
in the same vertical plane ; cell wall covered with tiny
granules, which are arranged in concentric series round
the angles and are reduced or wanting more remote
from them. Vertical view triangular, lateral margins
concave and angles slightly produced; centre of apex
nearly smooth.

i/

Zygospore unknown.

Length 30-31 pi ; breadth 33-35 ^ ; breadth of isth-
mus 7 '5 [i.

ENGLAND.- -Wigton Moor, W. Yorks! Dartmoor,
Devon (PI arris).

WALES. — Capel Curig, Carnarvonshire ! (Cooke &
Wills).

SCOTLAND.- -Near Aberdeen !

STAURASTRUM. 43

Geogr. Distribution. - Germany. Austria (form).
Servia. Switzerland. Norway.

This species is readily distinguished from St. Aricula by its
finer granulation, and by the fact that the angles of the semi-
cell are produced to form distinct cylindrical processes. St.
Avicula var. subarcuatum forms, in some ways, a connecting
link between the two species. By reason of its almost cylin-
drical processes, St. subcruciatum might well be considered a
member of Section I.

SECTION F.

Cells provided with numerous spines, either clothing the whole
surface of the cell-wall, or more or less restricted to the vicinity of
the angles.

* Spines few in number or restricted to the vicinity of the
angles, semicells sometimes with an apical series of spines
as well.

70. St. pungens.

71. St. Simonyi.

72. St. cristatiim.

73. St. oligacanihum.

74. St. trachygonum.

75. St. spimferum.

76. St. Picum.

77. St. horametrum.

** Spines numerous and more or less distributed over the whole

surface of the cell.

| Spines of considerable length and of two very distinct
kinds, a few at the angles being considerably stouter
than the rest.

78. St. setigerum.

"j"j~ Spines all more or less similar, or becoming gradually

longer towards the angles.

J Semicells broadly oval or rhomboidal, cells dis-
tinctly longer than broad, with an open sinus.

79. St. polytrichum.

80. St. saxonicum.

81. St. cumbricurn.

82. St.

44 BRITISH DESMIDIACE.E.

JJ Semicells elliptical or subpyrainidate-truncate, cells
as long as broad, or only a little longer than
broad, widest part of the semicell at the base or
middle region, never at the apex.

83. St. yladiosum.

84. St. teliferuni.

85. St. Hystrix.

86. St. Brebissonti.

87. St. pilosum.

88. St. hirsutuin.

89. St. muricatum.

90. St. pyramidatum*.

91. St. Ravenelii.

tjj Semicells narrowly subelliptic, broadest at the apex,
which is distinctly flattened.

92. St. erasiun.

93. St. erostdlum.

70. Staurastrum pungens Breb.
(PL CXXXV, figs. 8-10.)

Xtaurasimm y)ungens Breb. in Ralfs, Brit. Desm. 1848, p. 130, t. 34, f. 10 ;
Arch, in Pritch. Inf. 1861, p. 738 ; Pxabenh. Krypt.-fi. Sachs. 1863, p. 193 :
Flor. Europ. Alg. 1868, p. 214 ; Lund. Desm. Suec. 1871, p. 64 (forma) ;
Cooke, Brit. Desm. 1887, p. 144, t, 50, f. 6; Hansg. Prodr. Algentt.
Bohm. 1888, p. 214 : De Toni, Syll. Alg. 1889, p. 1148": Heimerl, Desm.
Alp. 1891, p. 606; Borge, Siissw. Chlor. Archang. 1894, p. 38; Roj^ &
Biss. Scott. Desm. 1894, p. 24 ; Comere, Desm. de France, 1901, p. 167,
t, 12, f. 24 ; West & G. S. West, Alg. N. Ireland, 1902, p. 45, t. 2, f. 29 ;
Brit, FreshAv. Phytoplankton, 1909, p. 203.

Cells small, about as long as broad, or a little longer,
deeply constricted ; sinus acute, opening widely ; semi-
cells broadly subfusiform or somewhat cuneate, dorsal
margin slightly convex, ventral margin very tumid,
angles subacute and ending in a strong spine ; apex of
semicell also provided typically with two accessory
spines between each pair of angles, projecting obliquely
upwards, but one or other of these may sometimes be
reduced or wanting. Vertical view triangular, sides
straight or only very slightly concave, angles broadly
rounded, tipped with a stout spine, and with two equally
strong spines projecting from each lateral margin. Cell-
wall minutely punctulate, punctulations arranged in
concentric circles round the angles.

Zygospore unknown.

STAURASTROI. 45

Length, without spines, 26-32*5 ^ ; breadth, without
spines, 26-31 ^ ; breadth of isthmus 10-11^; length
of spines about 7 p:

ENGLAND.- -Hampsfell, Lancashire ! Cross-in-hand,
Sussex (Ralfs). Penzance, Cornwall (Rolfs}.

SCOTLAND. — Aberdeen, Kincardine, Forfar, Perth

(Roy & Biss.).
IRELAND. --Near Cllenties, Donegal! Dublin and

Wicklow (Arch.).

Geoyr. Distribution- -France. Germany. Hungary.
Norway.. Sweden. Denmark. Bornholm. Finland.
N. Russia. United States.

The semicells of typical specimens of this species possess 9
spines, but irregularities in the number or position of the accessory
spines (i. e. those not at the angles of the cell) are not infrequent.

71. Staurastrum Simonyi Heimerl.
(PL CXXXV, figs. 1-4.)

M. Ximoiiyi Heimerl, Desm. alp. 1891, p. 606, t. 5, f. 23 ; Liitkem. Desm.

Millstattersees, 1900, p. 81 ; Borge, Sao Paulo Siisswasseralgen, 1918,

p. 53.
,S7. Reinschii West, Ala-. W. Ireland, IS'.IL>, p. 174 ; West & G. S. West, Alg.

S. England, 1897, p. 493 ; G. S. West. Variation Desm. 1899, p. 392,

t, 11, f. 16-20; West & G. S. West, Alga-fl. Yorks. 1902, p. 98; Alg.

N. Ireland, 1902, p. 47; Borge, Beitrage Alg. Schweden, 190(5, p. 48,

t. 3, f. 39.

Cells small, about as long as broad, deeply constricted ;
sinus acute, widening towards the exterior; semicells
usually elliptical or subfusiform, sometimes subsemi-
circular, dorsal and ventral margins as a rule almost
equally convex, lateral angles truncate and provided
with 2-4 sharp spines, apical margin with a series of
typically 4 spines between each pair of consecutive
angles, the two median ones being the largest and pro-
jecting conspicuously from the apex, the other two spines
sometimes entirely wanting : further with an occasional

«/ t_^ '

series of 4 smaller spines beneath the first series. Ver-
tical view triangular, lateral margins straight, slightly
concave or even a little convex, angles obtusely rounded

46 BRITISH

and provided with 2-4 spines, and with a series of 2 or
4 spines just within each lateral margin, the two median
ones in the latter case being more conspicuous, lateral
margins themselves sometimes provided with a secon-
dary series of 4 spines. Angles occasionally with
traces of about two or three concentric series of minute
distant denticulations, of which the apical series of
spines above-mentioned are well- developed members.

Zygospore unknown ?*

Length, not including spines, 19 '5-25 [j. ; breadth, not
including spines, 18-26 [Ji ; breadth of isthmus 6-7 '5 (ju

ENGLAND.- -Westmoreland ! (Biss.). Lancashire! W.
-and N. Yorks ! Surrey! Devon (Bennett). ? Dartmoor
(Harris).

WALES. — Capel Curig !, bog below Llyn Idwal !, Llyn-
y-cwm-ffynon !, Llyn Teyrn, Snowdon !, and Bettws-y-
coed (Roy), Carnarvonshire. Ffestiniog, Merioneth !

SCOTLAND.--? General, but scarce!, zygospores from
Glen Coe, Argyle (Roy & Biss.). Dumfries ! Hoy,
Orkneys !

IRELAND. — General in all boggy districts ! Clare
Island, Mayo !

Geogr. Distribution. — Austria. Norway. Sweden.
? United States. ? N. W. Canada. Brazil.

There lias been much confusion in the past with regard to
St. Simonyi Heimerl and St. Reinschii Roy, but there seems little
doubt now that the species recorded by W. & G. S. West from
various parts of the British Isles as St. Reinschii is in reality St.
Simonyi Heimerl. Both Dr. Lutkemiiller (' Desm. Millstatter-
sees,' 1900, p. 23) and Dr. Borge ('Sao Paulo Siisswasseralgen,"
p. 53) have pointed out this fact, and the writer believes that,
before his death, Professor West was in agreement with the two
continental algologists on this point. Whether or not St.
Reinschii Roy (= Staurastmm sp. Reinsch, 'Contrib. ad Alg.
Fung.' 1875, t. 17, f. 5) has actually been seen from the British
Isles is somewhat doubtful. Ro}^s first remarks on the subject

* The Desmid recorded by Roy & Biss. ('Scott, Desm.' 1894, p. 24) as Nf.
J\i inschii with zygospores is possibly St. Simony i Heimerl. The authors give
neither description nor figure.

STAURASTRUM. 47

('Desm. Perthshire,' 1877, p. 5 (sep.)) that his Desmid '"'nearly'
agreed with the figure of Reinsch lead one to understand that
the Scottish specimens were not identical with those of Reinsch,
and were perhaps more in agreement with Heimerl's later
described species. Roy also records a Desmid under the name
of St. Reinschii from Mull, and with zygospores from Glen Coe.
In no case, however, are figures given. Thus, in view of the fact
that Roy himself states that the specimens originally seen by
him were not absolutely identical with Reinsch's figures, the
writer is inclined to think that whether or not St. Reinschii
Roy actually exists as a valid species, all British specimens at
any rate recorded under that name have in all probability
belonged to St. Simonyi Heimerl. Until a Desmid complying
with Reinsch's figure and description has been accurately figured,
therefore, St. Reinschii Roy has provisionally been omitted from
the British list, The matter is further complicated by the fact
that both Cooke (' Brit. Desm.' 1887) and De Toni (• Syll. Alg.'
1889) have in their descriptions of St. Reiiischii united the
characters of two of Reinsch's species, those figured in ' Contrib.
Alg. Fung.' 1875, t. 17, figs. 4 and 5 respectively. These are two
distinct species according to Reinsch, and fig. 5 only represents
St. Reinschii.

72. Staurastrum cristatum (Nau.) Arch.
(PI. CXXXIX, fig. 5.)

Phycastruni (Pachyactinium) rristalum Xag. Gatt. einz. AL'. 1849, p. 127,
t. 8, C. f. 1.

Staurastrtu/i it it id it nt Arch, in Quart. Journ. Micr. Sc-i. 1860, p. 78, t. 7,
f. 3, 4 ; Rabenh. Krypt.-fl. Sachs. 1863, p. 193.

.sy. rri.sttitiiiii Arch, in Pritch. Infus. 1861, p. 738; P.abenh. Flor. Europ.
Alg. 1868, p. 215 ; Nordst. Desm. Spetsb. 1872, p. 40 : Jacobs. Desm
Danemark, 1875, p. 208, t. 8, f . 25 ; Kirchn. Alg. Schle.s. 1878, p. 170
Cooke, Brit. Desm. 1887, p. 144, t. 50, f. 7 ; Hansgirg, Prodr. Algenfl
Bohm. 1888, p. 215: De Toni, Syll. Alg. 1889, p. 1148: Borge, Bidr
Sibir. Chlor. 1891, p. 10 : West, Alg. W. Ireland, 1892, p. 173, t, 22, f. 16
Alg. Engl. Lake Distr. 1892, p. 18 ; Pvoy & Biss. Scott. Desm. 1893, p. 19
Borg. Alg. Faeroes, 1901, p. 233 ; Comere, Desni. de France, 1901, p. 167,
t. 13, f. 20 ; West & G. S. West, Alga-fl. Yorks. 1902, p. 98 ; Kaiser,
Algenfl. Traunstein u. Chiemgau, II, 1914, p. 158.

Didymidium XaegeUanum Reinsch, Algenfl. Frank. 1867, p. 167.

Staurastrum Xordstedtii Gutw. Wahr. d. Prioritat, 1890, p. 72 ; Flor. Glon.
Okol. Llowa, 1891, p. 71, t. 3, f. 22.

Cells small, about as long as broad, excluding the
spines, constriction fairly deep, sinus acute, opening

48 BRITISH DESMIDIACEJ?.

widely ; semicells broadly elliptical, dorsal margin
slightly convex, sometimes rather flattened on the
summit, ventral margin very convex, lateral angles some-
times slightly mamillate, furnished with a short spine
directed obliquely outwards, and with about 2 pairs of
spines projecting from the apical margin of each angle.
Vertical view usually triangular, sides straight, angles
acutely rounded, ending in a short spine, and with about
2 or 3 pairs of short spines on the apex in each angle,
directed outwards ; cell- wall punctate.

Zygospore unknown.

Length, without spines, 36-39 yL ; breadth, without
spines, 32-45 [i ; breadth of isthmus 15-19 [x.

ENGLAND. --Hawkshead and Hampsfell. Lancashire !
Strensall Common (IF. B. Turner) and Pilmoor, N.
Yorks ! Dartmoor, Devon (Harris). Cornwall (Marquand).

WALES. — Capel Curis; (Cooke & Wills) and Snowdon
(Roy).

SCOTLAND. — Sutherland, Ross, Inverness, Aberdeen,
Kincardine, Forfar, Perth, Argyle, Fife (Roy & Biss.}.

IRELAND. — Small lakes, Clifden to Roundstone, and
Derrvclare Lough, Co. Galwav ! Gleiwariff and Carran-

€/ «/

tu chill, Co. Kerry ! Dublin and Wicklow (Arch.}.

Geoyr. Distribution.- -France. Germany. Galicia and
Austria. Hungary. Norway. Finmark. Sweden. Den-
mark. Bornholm. N. Russia. Faeroes. Spitzbergen
Greenland. Siberia. Japan. India. Turkey-in-Asia.

73. Staurastrum oligacanthum Breb.
(PL CXXXIX, fig. 6.)

>S7. oligacanthum Breb. Arch, in Quart. Journ. Micr. Sci. 1866, p. 67 and
p. 189 ; Nordst. Desm. Arctose, 1875. p. 36, t. 8, f. 39 ; Cooke, Brit. Desm.
1887, p. 145, t. 50, f. 8 ; De Toni, Syll. Alg. 1889, p. 1149 ; Roy & Biss.
Scott. Desm. 1893, p. 23 ; West & G. S. West, Alga-fl. Yorks. 1901, p. 98 ;
Comere, Desm. de France, 1901, p. 168, t. 12, f. 18.

Cells small, about as long as broad, constriction fairly
deep, sinus acute, almost rectangular ; semicells de-
pressed hexagonal, apex truncate, lateral angles acute
and terminating in a conspicuous spine which is fre-

STAURASTRUM. 49

quently emarginate or compound ; lateral margins
provided with a series of spines extending from the
angle of the truncate apex nearly to the sinus, and with
a few spines just within each angle. Vertical view with
the lateral margins distinctlv concave, angles acute,

*j O

terminating in a sharp spine, and surrounded by one
or two concentric series of spines, with a pair of spines
at the base of each angle ; centre of apex smooth.
Spines often becoming emarginate.

Zygospore unknown.

Length about 44 u. ; breadth about 52 u ; breadth
of isthmus 25 ^ .

ENGLAND.--Bisley Bog, Lancashire (Roy). Mickle
Fell, N. Yorks ! Enbridge Lake and Woolton Pond,
Hants (Roy). Dartmoor, Devon (Harris).

WALES.- -Bettws-y-coed (Roy) and Capel Curig !, Car-
narvonshire.

SCOTLAND. --Xear Brin, Inverness ; near Cambus
O'May and Tomachar, Aberdeen ; near Loch Clunie,
Perth (Roy & Biss).

IRELAND.- -Dublin and Wicklow (Arch.).

Geogr. Distribution.- -France. Switzerland. G-alicia
in Austria. Xorway. Spitzbergen. Greenland (form).

St. oligacanthum is very closely allied to the preceding species,
with which it has probably been frequently confused by many
workers. As Archer (in ' Q. J. M. S.' vol. 6, 1866, p. 189)
points out, there are, however, distinct differences. In St.
cristatum the semicells are elliptic fusiform, both ventral and
dorsal margins are convex, and there is a mucronate angle on
each side (usually submamillate). In St. oligacanthum the
semicells are angular and roughly hexagonal with a markedly
truncate apex. In the vertical view the lateral margins of
St. cristatum are slightly convex, but in St. oligacanthum distinctly
concave.

Var. incisum West. (PL CXXXIX, fig. 7.)

Staurastrum oligacanthum var. incisum West, Alg. W. Ireland, 1892, p. 173,
t. 22, f. 17.

Semicells with a distinct incision in the lower lateral
margins ; vertical view triangular with slightly convex
margins.

VOL. v. 4

50 BRITISH DESMIDIACE^.

Length 39 (JL ; breadth 40 [i ; breadth of isthmus
22'5 p.

IRELAND.- -In small lakes, Clifden to Roundstone,
Galway !

74. Staurastrum trachygonum West.
(PL CXXXIX, fig. 3.)

St. trachygonum West, Alg. W. Ireland, 1892, p. 176, t. 23, f. 5.

Cells small, a little longer than broad, constriction
moderately deep, sinus fairly open ; semicells sub-
elliptical, apex truncate, cells provided with spines,
some of which are truncate, round the angles and on
the apex ; in vertical view triangular, sides very slightly
concave, angles rounded, the smooth apex provided
with a circle of short spines.

Zygospore unknown.

Length 32 '5 (JL ; breadth 28 \JL ; breadth of isthmus

7'5jJi.
IRELAND. — Kylemore, Co. Galway !

75. Staurastrum spiniferum West.
(PI. CXXXIV, fig. 7.)

St. spiniferum West, Alg. N. Wales, 1890, p. 16, f . 20 ; Freslnv. Alg. Maine, II,
1891, p. 3 ; West & G. S. West, Brit, Freslnv. Phytoplankt. 1909, p. 202.

Cells small, slightly longer than broad, deeply con-
stricted, sinus open and acute; semicells elliptical, with
about 8 spines round the periphery of each. Vertical
view triangular, sides very slightly concave, with a spine
at each angle and two others projecting from each side,
and with two or three scattered spines also on the apex.

Zygospore unknown.

Length, without spines, 25 [JL ; breadth, without
spines, 22 (x ; breadth of isthmus 7*5 [Jt ; length of spines
about 5(ji.

WALES.' — Ffestiniog, Merioneth !

Geogr. Distribution.- -United States.

STAURASTRUM. 51

76. Staurastrum Picum W. & G. S. West.

(PL CXXXVII, fig. 8.)

'Staurastrum Picum West & G. S. West, Xew and Int. Freslr.v. Alg. 1896,
p. 159, t. 4, f. 49 ; Brit, Fresh w. Phytoplankton, 1909, p. 202.

Cells small, a little broader than long, deeply con-
stricted, sinus open and subacuminate ; semicells
elliptic-fusiform, angles somewhat inflexed and subcapi-
tate, each with a single strong spine, slightly curved
and strongly inflexed ; dorsal margin provided with
about 6 paired spines which are short and curved ;
vertical view triangular, angles obtuse and subcapitate,
sides slightly concave, with about 6 paired spines along
each ; cell-wall smooth.

Zygospore unknown.

Length, without spines, 20 IJL ; with spines, 25 IJL ;
breadth without spines, 23-26 u. ; with spines, 29-34 M, ;
breadth of isthmus 8 \L .

IRELAND. — Glen Caragh, Co. Kerry !

77. Staurastrum horametrum Koy £ Biss.

(PL CXXXIX, fig. 4.)

St. Itoraniftruni Roy & Biss. Scott. Desni. 1893, p. 21, t. 3, f. 2 ; Gutvr.
Norm. Alg. Nov. 1896, p. GO. t. 7, f. 72.

Cells medium sized, a little longer than broad, " hour-
glass ' ' shaped, constriction opening rectangularly, sides
about straight ; semicells widem'ng upwards, angles sub-
acute, ends flatly convex ; angles with 3 or 4 rows of
crowded, short, simple, acute, stout spines ; end view
triangular or quadrangular, sides slightly concave, angles
acutely rounded, very spiny, 2 or 3 rows of spines
across the angles, and a circle of 15 spines around the
centre in the triangular form, and of 20 in the quadran-
gular. Isthmus about half the thickness of the semicell.
Membrane smooth (Roy & Biss.).

Zygospore unknown.

Length about 57-65 ^ ; breadth 48-59 y. ; breadth of
isthmus 18-24[i.

52 BRITISH DESMIDIACE^E.

SCOTLAND. --Powlair, Slewdrum, Heughhead, Birk-
hill, Tomachar, Dinnet, Glen Clunie, Aberdeen ; near
Crathes, and near Durris Bridge, Kincardine ; Glen
Isla, Forfar (Roy & Biss.).

Geogr. Distribution. — Galicia in Austria. Faeroes.

This species is nearest to St. asperum Breb. in the form of its
semicells, but the arrangement of the spines, which are almost
entirely confined to the angles, distinguishes it.

78. Staurastrum setigerum Cleve.
(PL CXXXVI, figs. 13, 14.)

St. setigeniiti Cleve, Sverig. Desm. 1864, p. 490, t. 4, f. 4 ; Rabenh. Flor.

Europ. Alg. 1868, p. 216; Nordst. Norges Desm. 1873. p. 31 ; Welle,

Desm. U. S. 1884, p. 141, t. 45, f. 26, 27 ; De Toni, Syll. Alg. 1889, p. 1168;

Roy & Biss. Scott, Desm. 1894, p. 25, t. 3, f. 9 ; Eichler, Mat. Flor.

Miedz. 1894, p. 62 ; Comere, Desm. de France, 1901, p. 167, t. 12, f. 2 ;

Borge, Alg. erst, Regnell. Exped. II, Desm. 1903, p. 108 ; West & G. S.

West, Brit. Freshw. Phytoplankton, 1909, p. 202 ; Borge, Sao Paulo

Siisswasseralgen, 1918. p. 53.
St. Royanum Arch, in Quart. Journ. Micr. Sci. 1877, vol. 17, p. 103 ; Cooke,

Brit. Desm. 1887, p. 152.

Cells of medium size, a little longer than broad,
deeply constricted, sinus acute and open ; semicells
elliptical, ventral margin more convex than tbe dorsal,
angles obtusely rounded arid provided with 2-5 (usually
3) long stout spines arranged in a vertical row, or some-
times (according to Archer) in a circle like the shafts of
a shuttlecock. Surface of cell provided with a number
of long but more delicate spines than those at the angles,
arranged in distant obscure circles round the angles.
Vertical view triangular, sides nearly straight, angles
rather acutely rounded. Chloroplast axile, with a
central pyrenoid in each semicell.

Zygospore unknown.

Length, without spines, 50-56 \L ; breadth, without
spines, 42-45 [JL ; breadth of isthmus 14*5-17[Ji ; length
of angular spines 15-20[ji; length of more delicate
spines about 10-1 2 pi.

WALES. — Capel Curig, Carnarvonshire !

STAURASTRUM. Oo

SCOTLAND.— Glen Coe, Argyle (Arch.). Rhiconich,
Sutherland ! Xear Tarbert, Harris, Outer Hebrides !

IRELAND.- -Dublin and Wicklow (Arch.).

Geogr. Distribution.- -France. Norway. Sweden. Fin-
land. Poland. Central Africa. United States. N. W.
Canada. Brazil. Paraguay.

St. setigerum is distinguished from all other spiny species of
Staurastnun by the possession of two distinct kinds of spines,
the stout angular spines contrasting strongly with those on the
laces of the semicell. which are much more delicate.

79. Staurastrum polytrichum (Perty) Rabenh.
(PL CXXXVI, figs. 8-10.)

Phyca6tnini palytrirlnuii Perty, Kleinst. Lebeiisf. 1852, p. 210, t. 10, f. 24.
Staurastrum Pringsheimii Reinsch, Spec. Gen. Alg. 1867, p. 22, t. 5, A, B,

f. 1-8; Arch, in Journ. Bot. 1874, p. 93; R.-ins.-h, C.mtr. Alg. Fung.

1875, p. 90, t. 10, f. 4: Cooke, Brit. Desm. 1887, p. 152, t. 52, f. 4;

Espensch. Desm. berg. Landes, 1903, p. 103, t. 2, f. 19.
>7. polytricltuHi Rabenh. Flor. Europ. Alg. 18(38, p. 214; Lund. Desm.

Suec. 1871, p. 63; Xordst. Xorges Desm. 1873, p. 30; De Toni, Syll.

Alg. 1889, p. 1169; Racib. Desmidyja Ciastonia, 1892, p. 389; West,

Alg. W. Ireland, 1892. p. 175, t. 22, f/18 ; Roy & Biss. Scott. Desm. 1893,

p. 23, t. 3, f. 8 ; Turn. Freshw. Alg. E. India, 1893, p. 113. t. 13, f. 16 ;

West & G. S. West, Alg. 8. England, 1897, p. 494 : Gutw. \Vvkaz Glonow

Wadow.-Makow. 1897, p. 158 ; Schmidle, Lappmark Siisswasseralgen,

1898, p. 54 ; Liitkem. Desm. Millstattersees, 1900. p. 23 ; West & G. S.

West, Alga-fl. Yorks. 1902, p. 99 ; Alg. X. Ireland, 1902. p. 48 ; Scott.

Freshw. Plankt. I, 1903, p. 529 : Him, Desm. Finnland, 1903, p. 22 :

G. 8. West, Brit. Freshw. Alsr. 1904, p. 172, f. 65 D : ('ushman in Bull.

Torr. Bot, Club, 1905, p. 228, t. 8, f. 18 (var.).
St. Pringsheimii var. clupln-tndjor Turn. Xew Rare Desm. 1885, p. 939,

t. 16, f. 24.
St. teliferum var. convexuni Benn. Alg. Ensd. Lake Distr. l.ssi.i. p. 11, t. 2,

f. 21-23.

Cells of medium size, about lj times longer than

•* ^t ^3

broad, deeply constricted, sinus acute and sometimes
fairly open ; semicells elliptical or subelliptical, cell- wall
covered with fairly long acute spines, arranged in
obscure circles round the angles, and sometimes visible
as longitudinal rows on the faces. Vertical view tri-
angular, sides straight or almost imperceptibly concave,
angles somewhat obtusely rounded, spines becoming
shorter towards the centre of the apex, which is quite
smooth.

54 BRITISH DESMIDIACE^E.

Zygospore of t}^pe unknown.*

Length, without spines, 48-67 (JL ; with spines, 54-80 [A;
breadth, without spines, 41-48 [JL ; with spines, 50-70 (JL ;
breadth of isthmus 15-22 [i ; length of spines 5-11 [i ;
diam. zygosp. (var.) without spines, 53 ^ ; with spines,.
78 pi.

ENGLAND.- -Westmoreland ! (Biss.). W. andN. Yorksf
Warwicks ! Surrey ! Hants ! Devon (Bennett, Harris).
Cornwall (Bennett).

WALES.- -Llyn Padarn, Llyn Idwal, Llyn Gfwynant,
Capel Curig ! (Cooke & Witts) and Snowdon (Roy), Car-
narvonshire !

SCOTLAND.- -Eoss, Inverness, Aberdeen, Kincardine,
Forfar, Perth !, Argyle, Wigtown (Roy & Biss.). Plank-
ton of Loch Shin, Sutherland !

IRELAND.- -Lough Anna, Donegal ! Clare Island, Co.
Mayo ! Small lakes, Clifden to Roundstone, Co. Galway !
Cloonee Lough, Co. Kerry ! Dublin and Wicklow (Arch.).
Stream, N. of Newcastle, Co. Down !

Geogr. Distribution. — Germany. Switzerland. Galicia
and Austria. Norway. Sweden. Finland. S. Russia.
India. United States. N. W. Canada. Argentine.

This species is one of the most beautiful of the spiny Staurastra.
It is distinguished from St. gladiosum Turn, by its greater size
and relatively greater length, and by the uniform character
and regular arrangement of its more numerous spines.

80. Staurastrum Saxonicum Bulnh.
(PL CXXXVII, fig. 7.)

Staurastrnin sp. Bulnh. Einige Desm. 1859, p. 22, t. 2, f. 7.

St. Saxonicum Bulnh. in Rabenh. Krypt.-flor. Sachs. 1863, p. 190 ; Rabeiih.

Flor. Europ. Alg. 1868, p. 213 ; Nordst. Desm. Spetsb. 1872, p. 40 ; Desm.

Arct, 1875, p. 35 ; Boldt, Desm. Gionland, 1888, p. 36; De Toni, Syll.

Alg. 1889, p. 1173 ; Borg. Desm. Brasil, 1890, p. 949 ; Roy & Biss. Scott.

Desm. 1893, p. 25, t. 3, f. 10 ; West & G. S. West, Alg. S. England, 1897,

p. 494 : Alga-fl. Yorks. 1902, p. 99 ; Cushman in Rhodora, 1903, p. 222.

The zygospore of St. polytrichum var. readingense Cushman has been
described in 'Bull. Torr. Bot. Club,' 1905, p. 228. In general form it is
spherical, and it is thickly beset with peculiar spines which are very broad at
the base ; at the apex they are first trifurcate and then bifid. The whole zygo-
spore including the spines is thickly covered \vith irregular elongated granules.
It is a very extraordinary zygospore (see PL CXXXVI, f. 11).

STAURA STRUM. 55

? St. Xotari.sii Delp. Spec. Desm. subalp. 1877, p. 157, t. 13, f. 1-2.

? St. bullosum Benn. Freshw. Alg. Engl. Lake Distr. 1886, p. 11, t, 2, f. 18-20;

Cooke, Brit, Freshw. Alg. 1887, p. 152, t, 51, f . 5 ; De Toni, Syll. Alg.

1889, p. 1170.

Cells of rather more than medium size, about 1 J times
longer than broad, deeply constricted, sinus acute,
opening widely ; semicells broadly oval, angles very
obtusely rounded ; cell- wall closely covered with
numerous short acute spines, evenly distributed except
that they are wanting in the centre of the apex of the
semicell. Vertical view 3- (rarely 4- or 5-) angular, sides
very slightly convex, angles bluntly rounded. Cell-wall
minutely punctate.

Zygospore unknown.

Length, without spines, 77-79 u ; with spines, 85-
86 (JL ; breadth, without spines, 58-65 \L ; with spines,
72-74 \L ; breadth of isthmus, 21-22 \L ; length of spines
3-8 fi.

ENGLAND.- -Loughrigg, Westmoreland (Bennett). Den-
holme, Cam Fell and near Brickden, W. Yorks ! New
Forest, Hants ! Dartmoor, Devonshire (Harris).

SCOTLAND.- -Xear Mill of Maidencraig, Haughton,
Tillyfour, below Aboyne, Dinnet, Koynach Moor in
Cromar, Castleton, Braemar, Aberdeen ; near Durris
Bridge, Cainmie, Dalbrake, Slack of Birnie, Kincardine ;
Lundie Bog, Easter Ogil in Fern, Forfar (Roy & Biss.).
Plankton of Loch Trebister, Shetlands !

Geogr. Distribution- -France. Germany. Galicia and
Austria. Italy. Norway. Sweden. Bornholm. Nova
Zembla. Spitsbergen. Greenland. United States.
Brazil.

St. Saxonicum is distinguished from St. polytrichum by the
form of its semicells, which are relatively longer and more
broadly oval, and its shorter spines are also more numerous.

81. Staurastrum cumbricum West.
(PL CXXXVII, figs. 13, 14.)

St. cumbricum West, Alg. X. Wales. 1890, p. 16, t. 5 f. 5, t. 6, f. 30.

Cells rather large, li times longer than broad, deeply

56 BRITISH DESMIDIACE.E.

constricted, sinus open, almost rectangular ; semicells
broadly elliptical ; cell- wall beset with spines of varying
lengths, the longest being arranged at the angles.
Vertical view triangular with slightly convex sides.
Chloroplast axile with a central pyrenoid in each semicell.

Zygospore unknown.

Length 76-85 (JL ; breadth 55-65 JJL ; breadth of isth-
mus 25 [Ji ; length of spines at angles 11-15 [A.

ENGLAND. — Lindeth, Westmoreland !

WALES. — Capel Curig, Carnarvonshire !

This species differs from St. polytrichum in its larger size and
in its relatively sharper spines of varying lengths. St. Saxonicum
differs in its snorter uniform spines.

Tar. cambricum West. (PL CXXXVII, figs. 15, 16.)

St. cumbricum var. cambricum West, Alg. N. Wales, 1890, p. 17, t. 5, f. 0,
t, 0, f. 37.

Differs from the type in its narrower isthmus and
somewhat rhomb oidal form of the semicells.

Length 62-83 ^ ; breadth 48-64 JJL ; breadth of isthmus
13-20 pi.

WALES. — Capel Curig. Carnarvonshire !

82. Staurastrum echinatum Breb.
(PL CXXXVII, fig. 12.)

St. echinatum Breb. in Ralfs, Brit, Desm. 1848, p. 215, t. 35, f. 24 ; Arch, in
Pritch. Inf. 1861, p. 739; Rabenh. Flor. Europ. Alg. 1868, p. 213;
Kirchn. Alg. Schles. 1878, p. 166 ; Wolle, Desm. U. S. 1884, p. 141,
t. 45, f. 31. 32 (fig. not accurate) ; Hansg. Prodr. Algenfl. Bohm. 1888,
p. 214 ; West, Desm. Maine, 1888, p. 340 ; De Toni, Syll. Alg. 1889,
p. 1171 ; Turn. Freshw. Alg. E. India, 1893, p. 112, t. 16, f. 48 ; Roy &
Biss. Scott. Desm. 1894. p. 19 ; Comere, Desm. de France, 1901, p. 172,
t, 12, f. 22 ; ? West & G. S. West, Freshw. Chlorophy. Koh Chang, 1901,
p. 177, t. 3, f. 31 (forma) ; Cushman in Rhodora, 19*03, p. 224 and 253 ;
? G. S. West, Alg. Third Tanganyika Expedit. 1907, p. 125 (forma) ;
Borge, Botan. Notiser, 1913, p. 49, t. 3, f. 36.

Cells small, slightly longer than broad, deeply con-
stricted, sinus open and acute-angled ; semicells broadly
elliptical, angles rounded ; cell- wall covered with rather
short spines, which are considerably dilated at the base,

STAURASTRUM. 57

arranged in horizontal and vertical series across the faces
of the semicell. Vertical view triangular, sides straight
or slightly convex, each with about 8 spines along the
margin ; apex of semicell provided with 2 or 3 series of
spines parallel to the marginal one, centre of apex smooth.

Zygospore unknown.*

Length 33 p. : breadth 28 ^ ; breadth of isthmus
12'o (JL ; length of spines about 2'5 JJL.

WALES. — Capel Curig, Carnarvonshire (Roy}.

SCOTLAND.- -Verv rare ; near New Pitslio-o. and South

«/

of Birsemore. Aberdeen ; Canlochan, Forfar ; Bracklin,
Perth (Roy & Bus.).

Geogr. Distribution. — France. Germany. Switzerland.
Galicia in Austria. Servia. Xorway. Sweden (form).
Poland. Central Russia. Faeroes. Greenland. ? India.
? Siam. E. and Central Africa. United States. Alaska.

Fig. 12, PL CXXXVIi; is copied from a drawing by the late
Dr. Lutkemiiller made by him from de Brebisson's original
exsiccata. It certainly agrees more with de Brebisson's figure in
Kalfs' ' British Desmidiese ' than any other figure previously
published. St. eclrinatum had never been observed in Britain by
either the late Professor G. S. West or W. West, and the figures
published by them of specimens from Koh Chang and Africa
obviously deviate considerably from the type, and were only
referred to this species after much deliberation. They would
possibly be more correctly placed in some other species. A very
characteristic feature of St. echitmtiun is the peculiar and sudden
dilatation of the spines at their base (see in this connection the
figure of Borge in ' Botan. Xotiser,' 1913, t. 3, f. 36, which also
gives some indication of this character).

83. Staurastrum gladiosum Turn.
(PL CXXXVII, figs. 1, 2.)

St. gladiosum Turn. Xew Rare Desm. 1885, p. 6, t. 16, f. 21 ; De Toni,
Syll. Alg. 1889, p. 1172; West, Alg. X. Wales, 1890, p. 16, West & G. S.
West, Alg. 8. England, 1897, p. 494.

* Gronblad (' Desm. Keuru,' 1920, p. 62, t. 1, f. 38-40) figures a Staurastrum
with zygospore which he refers with some doubt to St. echinafnm Breb. In
the opinion of the writer this Desmid does not belong here, since the spines
are far too long. The zygospore has therefore been ignored.

58 BRITISH DESMIDIACE^E.

Cells rather under medium size, about as long as
broad, sinus acute and not very widely open ; semicells
elliptic -reniform, dorsal and ventral margins almost
equally convex, cell wall uniformly covered with stout
spines, about 14-20 visible along the peripheral margin,
arranged in obscure circles round the angles, and more
or less scattered further away. Vertical view triangular,
sides slightly concave, angles broadly rounded, about
9 spines visible along each lateral margin, spines in the
centre of the apex sparsely scattered.

Zygospore unknown.

Length, without spines, 37*5-41 pi ; with spines,
47*5-51 [x ; breadth, without spines, 37 '5-40 pi; with
spines, 48-50 pi ; breadth of isthmus 11-1 2 pi.

ENGLAND. — Gunwen Moor, Cornwall !

WALES. — Capel Curig, Carnarvonshire !

Geogr. Distribution. --India (var.). United States.

Var. delicatulum W. & G. S. West. (PL CXXXVII,

%. 3.)

St. gladiosiun var. delicatulum West & G. S. West, Notes Algse, II, 1900,
p'. 296, t. 1, f. 14 ; Alga-fl. Yorks. 1902, p. 99.

A variety with more delicate spines, which are some-
times slightly curved, and are far less numerous more
remote from the angles.

Length, without spines, 37*5 pi: with spines, 44 pi;
breadth, without spines, 38 '5 pi; with spines, 50 pi;
breadth of isthmus, 14 pi.

ENGLAND.- -Malham Tarn, W. Yorks!

The form of the cell in this variety, also the number and length
of the spines, are nearer to those of St. gladioswn than any other
species. The semicells are more depressed than in St. teliferum,
and the spines are longer and more delicate.

84. Staurastrum teliferum Ralfs.
(PI. CXXXVI, figs. 2-6.)

St. teliferum Ralfs. Brit. Beam. 1848, p. 128, t. 22, f. 4, t, 34, f. 14 ; Arch, in
Pritch. Inf. 1861, p. 739, t. 3, f. 20-21 ; Rabeiih. Krypt.-fl. Sachs. 1863,
p. 190 ; De Not. Desm. Ital. 1867, p. 50, t. 4, f. 40 ; Rabenh. Flor. Europ.

STAURASTROI. 59

Alg. 1808, p. 212; Xordst. Xorges Desm. 1873, p. 30; Delp. Desm.

subalp. 1877, p. 148, t. 11, f. 1-4; Kirchn. Alg. Schles. 1878, p. 170;

Gay, Monogr. loc. Conj. 1884, p. 68 ; Wolle, Desm. U. 8. 1884, p. 140,

t. 45, f. 4 ; Cooke, Brit. Desm. 1887, p. 151, t. 52, f. 2 ; Boldt, Desmid.

Gronland, 1888, p. 36 ; West, Desm. Mass. 1889, p. 5 ; De Toni, Syll.

Alg. 1889, p. 1167; Anderss. Sverig. Chlor. 1890, p. 12; West, Ate.

W. Ireland, 1892, p. 175, t. 24, f. 5 ; Alg. Eng. Lake Distr. 1892,

p. 19 ; Liitkem. Desm. Attersees, 1893, p. 564 ; Roy & Biss. Scott.

Desm. 1894, p. 26 ; West & G. S. West, Alg. 8. England, 1897, p. 493 ;

Coniere, Desm. de France, 1901, p. 171. t. 12, f. 17 ; West & G. 8. West,

Alga-fl. Yorks. 1902, p. 99; Alg. N. Ireland, 1902, p. 48; Schroder,

GaUertbildung Alg. 1902, p. 163, t, 7, f. 14 : Teodoresco, Mater, flor.

Alg. Rouman. 1907, p. 184 : West & G. 8. West, Brit. Freshw. Phyto-

plankton, 1909, p. 175 ; Kaiser, Beitr. Algenfl. Traunstein u. Chiemgau,

1914, p. 153.

Didymidium Hystrix B. ma jus Reinsch, Algenfl. Frank. 1867, p. 171.
Staurastrum polytrichum var. alpiniim Schmidle, Weit. Beitr. Algenfl.

Rheineb. u. Schwarzwald, 1895, p. 81, t. 1. f. 20.
Xanthidium homceacanthum Schmidt. Grundl. Ateenfl. Liineburg. Heide,

1903. p. 17. t. 1. f. 4.

Cells rather under medium size, about l\ times longer

.1 O

than broad, deeply constricted, sinus acute and open ;
semicells elliptical, with the angles broadly rounded ;
cells provided with a number of short stout spines,
arranged chiefly at the angles, with a few sparsely
scattered on the faces. End view triangular, sides
somewhat concave, angles broadly rounded, spines more
numerous at the angles and almost wanting in the
middle of the lateral margins. Chloroplast axile, with
a central pyrenoid in each semicell. and a pair of lobes
extending into each angle.

Zygospore orbicular, provided with a number of long
stout spines, forked at the apex.

Length, without spines, 32-56 JJL : with spines, 40-
64 u : breadth, without spines, 27-37 pi ; with spine-.
40-45u.; breadth of isthmus 8-1 0[x; diam. zygosp.,
without spines, 27 '5 pt ; length of spines 15 [i.

ENGLAND.- -Plankton of Codale Tarn and Easedale
Tarn. Cumberland ! Westmoreland and in the plankton
of Ennerdale Water ! Lancashire ! W., N., and E. Yorks !
Cheshire (Roy). Berks (Griffiths). Burnham Beeches,
Bucks ! Surrey ! Sussex (Ralfs). Hants ! Wilts ! Devon !
(Harris, Bennett). Cornwall !

WALES.— General ! (At 2200 feet on Glyder Each).
In the plankton !

60 BRITISH DESMIDIACE^E.

SCOTLAND. — General, occasionally with zygospores
(Roy & Biss.}. Rare in the plankton ! Lewis and
Harris, Outer Hebrides ! Orkneys and Shetlands, and
in the plankton !

IRELAND. — General ; zygospores from near Round-
stone, Co. Galway ! Clare Island !

Geogr. Distribution.- -France. Germany. Switzerland.
Galicia and Austria. Servia. Roumania. Italy. Norway.
Sweden. Denmark. Bornholm. Finland. N. and S.
Russia. Faeroes. Iceland. Greenland. Siberia. Central
China (var.). Japan. Burma. Azores. United States.
Brazil.

This is one of the most widely distributed of the British

*/

Desmids, and is frequent in nearly all bog collections. The
form described by Bennett (' Alg. Engl. Lakes.' 1886, p. 11,
t. 2, f. 21 and 22) as St. teliferum var. convex-urn does not belong
to this species, but is more probably a form of St. polytriclium
Perty.

Forma obtusa West. (PL CXXXVI, fig. 7.)

St. teliferum forma obtusa West, Alg. W. Ireland, 1892, p. 175, t. 24, f. 6.

A form in which the spines are reduced to very short
obtuse nodules.

Length, without spines, 45 (x ; with spines, 50 ^ ;
breadth, without spines, 39 [*. ; with spines, 45 ^ ;
breadth of isthmus 12 '5 p.

IKELAND. — Small Lakes, Clifden to Roundstone, Co.
Galway !

85. Staurastrum Hystrix Ralfs.
(PI. CXXXVI, fig. 1.)

>7. Hystrix Ralfs, Brit. Desm. 1848, p. 128, t. 22, f. 5 ; Arch, in Pritch. Infus.

1861, p. 739; Rabenh. Flor. Europ. Alg. 1868, p. 213; Wolle, Desm.

U. S. 1884, p. 142, t. 45, f. 14-16 ; Cooke, Brit. Desm. 1887, p. 151, t. 52,

f. 3; De Toni, Syll. Alg. 1889, p. 1167; West, Alg. Engl. Lake Distr.

1892, p. 19 ; Roy & Biss. Scott. Desm. 1893, p. 21 : Schmidle, Beitr.

Alp. Alg. 1895, p. 31 ; West & G. S. West, Alg. 8. England, 1897, p. 493 ;

Comere, Desm. de France. 1901, p. 171, t. 13, f. 9: Espenscheid, Alg.

berg. Landes, 1903, p. 103, t. 2, f. 20.
Didymidium (Staurastrum) Hystrix A. minus a trigonum Reinsch. Algenfl.

Frank. 1867, p. 171.

STAURASTRUM. 61

Cells small, about lj to li times longer than broady
deeply constricted, sinus narrow and acute ; semicells
elliptic-oblong, dorsal margin somewhat flattened,
angles very bluntly rounded, with 2 or 3 scattered
spines and about 6 or 8 others arranged in a circle just
beneath. Vertical view triangular, rarely quadrangular,
lateral margins slightly concave, angles obtusely rounded;
spines confined to the region of the angles. Cell-wall
smooth.

Zygospore unknown.

Length, without spines, 25 (j. ; breadth, without spines,
21 (JL ; breadth of isthmus 6'5 JJL ; length of spines 3-4 [i.

ENGLAND.- -Brother's Water, Westmoreland ! Ditton
Common, near DeviFs Jumps, and Thursley Common,
Surrey ! Xear Storrington, Sussex (Rolfs). Dartmoor,
Devon (PI arris).

WALES. — Capel Curig, Carnarvonshire ! Dolgelly,
Merioneth (Ralfs).

SCOTLAND. — Sutherland, Inverness, Aberdeen, For far,
Perth, Argyle, Arran (Roy & Biss.). Near Balallan,
Lewis, and Tarbert, Harris, Outer Hebrides !

IRELAND.- -Ballynahinch, Galway ! Leinster (Adams).
Dublin and Wicklow (Arch.).

Geogr. Distribution.- -France. C4ermany. Switzerland.
Austria (var.). Hungary. Norway. Sweden. Poland.
United States. Brazil.

This species is very similar to St. teliferum Ealfs, but is
readily distinguished from that species not only by its smaller
size and the more restricted arrangement of the spines, but also
in the form of the semicells, which are elliptic oblong and more
depressed than those of St. teliferum.

86. Staurastrum Brebissonii Arch.
(PL CXXXVII, figs. 4, 5.)

Staurastruni jjilosiini Breb. Liste Desm. 1856, p. 141, t. 2, f. 49; Cleve,

Sverig. Desm. 1863, p. 490, t. 4, f. 3.
St. Brebissonii Arch, in Pritch. Inf. 1861, p. 739 ; Lund. Desni. Suec. 1871,

p. 63 ; Xorclst. Desm. Spetsb. 1872, p. 133 ; Desm. Arctose, 1875, p. 34 ;

Wolle, Desm. U.S. 1884, p. 141, t. 45, f . 5, 6 ; Cooke, Brit. Desm. 1887,

62 BRITISH DESMIDIACE^.

p. lf>o. t. f>2, f. 0; De Toni, Syll. Al«r. 188!), p. lir>(> ; Gutwin. Fl<>r.
.don. >\\ •< Julie. 1892, p. 73 ; Roy & Biss. Scott. Desni. ISO.'J, p. 18 ; Liitkem.
Desm. ]\Iillslattersees, 1900, p. 22; Com ere, Desm. de France, 1901,
p. 171, t, 12, f. 6 ; W. & G. S. West, Alg. N. Ireland. 1902, p. 48.
>V. i>U<>Kiun b. Brebissoaii, Ivabenh. Flor. Europ. Alg. 1808, p. 212.

Cells small, about as long as broad, or sometimes not
quite as long as broad, deeply constricted, sinus acute,
widening outwards; semicells elliptical or elliptic-fusi-
form, angles rather acutely rounded, cell-wall provided
with numerous fine, acute spines, which are more
crowded and longer near the angles, around which they
are arranged in concentric circles. Spines in front view
of semicell arranged in longitudinal rows, becoming
smaller and more distant towards the centre of the face.
Vertical view usually 3- (-5-) angular, sides distinctly
-concave, angles acutely rounded, spines wanting in the
centre of apex.

Zygospore according to Cleve's figure spherical with
numerous complex spines.

Length, without spines, 34-48 [i ; breadth, without
spines, 40-62 pi; breadth of isthmus 13[j.; length of
spines at the angles about 2*5^ ; diam. zygosp. 72^.

ENGLAND. — Near Bowness, Westmoreland (Bissett).
Leicestershire (Roy). Sutton Park and Harborne, War-
wicks ! Hants (Roy).

WALES. — Capel Curig and Glyder Fach (at 2200 feet),
Carnarvonshire !

SCOTLAND.- -Ross, Aberdeen, Kincardine, Forfar,
Perth, Fife (Roy & Biss.).

IRELAND. — Mayo ! Dublin and Wicklow (Arch.).
Lough Derryadd, Armagh !

Geogr. Distribution.- -France. Germany. Galicia in
Austria. Hungary. Servia. Norway. Sweden. Den-
mark. Finland. N. Russia. Nova Zembla. Spitsbergen.
Greenland. United States and Alaska. Patagonia.
Antarctic.

Good figures of St. Brebissonii have always been wanting,
and it is evident that different workers have had different
conceptions of the species. The figure given (PL CXXXVII,
fig. 4) is copied from a drawing by the late Dr. Lutkemiiller.

STAURASTRUM. 63

The chief characters seem to be the depressed semicells,
separated by a fairly open sinus, and the spines considerably
longer at the angles. Liitkemiiller's end view differs con-
siderably from that of de Brebisson in its very much more
concave lateral margins and more acute angles.

Lundell criticises Cleve's figure of the zygospore of this species
(described by Cleve under the name of St. pihsum), since he
found that instead of having appendages first trifurcate and
then bifid as figured by Cleve, the zygospores have spines which
are 3 or 4 times dichotomous at the apex. Lundell also states
that the lower undivided part of the process is a little shorter
than figured by Cleve.

Yar. brevispinum West. (PL CXXXVII, fig. 6.)

.S7. Brebissonii var. brevispinum West, Alsr. Engl. Lake Di.str. 1892, p. in,
t. 9, f . 20.

Differs from the type in its relatively shorter and
stouter spines, and also in the relatively greater length
of the cells.

Length 49 pi ; breadth, not including the spines, 42 5 (JL ;
with spines, 45 y. ; breadth of isthmus 17 '5 a.

ENGLAND.- -Brother's Water, Westmoreland !

Geogr. Distribution.- -United States.

87. Staurastrum pilosum (Xag.) Arch.
(PL CXXXVIII, figs. 1-3.)

Phycasfrum (Amblyactinium) •pilosum Nag. Gatt. einz. Ate. 1S49, p. 126,
t. 8, A, f. 4,

Staurastrum pilosum Arch, in Pritch. Inf. 1861, p. 739 ; Rabenh. Flor.
Europ. Alg. 1868, p. 212 ; Wittr. Skandinav. Desin. 1869, p. 17, t. 1,
f. 8; Xordst. Desm. Arctoae, 1875, p. 34 ; Gay, Monosr. loc. Conj. 1884,
p. 68 ; Cooke, Brit. Desm. 1887, p. 150, t, 52", f . 5 : De Toni, Syll. Alg.
1889, p. 1166; Anderss. Sverig. Chlor. 1890, p. 12: West, Alg. W.
Ireland, 1892, p. 175 ; Alg. aq. dulc. Lusitan. 1892, p. 1503 ; Roy & Biss.
Scott. Desm. 1893, p. 23 ; West & G. S. West, Alg. S. England, 1897,
p. 494; Borg. Freshw. Alg. Faeroes, 1901, p. 230; West & G. S. West,
Alg. N. Ireland, 1902, p. 48 ; Alga-fl. Yorks. 1902, p. 99.

St. saxonicum f. tenue Schmidt, Gruncll. Algenfl. Liineburg. Heide, 1903,
p. 19, t, 2, f. 14.

Cells small, about as long as broad, deeply constricted,
sinus acute, opening widely; semicells subelliptical or
subfusiform, angles somewhat acutely rounded, cell- wall
covered with delicate spines arranged in concentric

64 BRITISH DESMIDIACE^.

series round the angles. Vertical view triangular, sides
strongly concave, angles acutely rounded.

Zygospore, according to Wittrock, spherical, provided
with a number of stout processes, trifid or bifid for about
half their length, and each part bifid again at its apex.*

Length, without spines, 42'5-44 pi ; breadth 38-47 [JL ;
breadth of isthmus 1 1 p ; length of spines about 2 y. ;
diam. zygosp., without spines, 56-57 [i ; with spines,
88 pt.

ENGLAND. — Cumberland ! Westmoreland ! Lanca-
shire ! W. and N. Yorks ! Essex ! Oxford ! Plankton
of Bracebridge Pool, Warwicks ! Surrey ! Kent !
Hants ! Devon ! Cornwall !

WALES.- -Fairly general !

SCOTLAND. — General, but scarce ; zygospores from
Cammie, Kincardine and GlenCoe, Argyle (Roy <& Biss.).
Newton Stewart, Wigtown ! Near Lochmaddy, N. Uist,
and N. of Stornoway, Lewis, Outer Hebrides. Plankton
of the Orkneys and Shetlands.

IRELAND.- -Donegal ! Mayo and Clare Island ! Gal-
way ! Kerry! Dublin and Wicklow (Arch.). Down (at
2000 feet on Slieve Donard) ! Londonderry !

Geogr. Distribution. — Germany. Galicia and Austria.
Hungary. Norway. Sweden. Bornholm. Portugal.
Finland. N. Russia. Faeroes. Iceland. Spitzbergen.
Greenland. Siberia. Central Africa (var.).

It is in the case of a species such as St. pilosum that the loss
of Professor West's critical remarks is to be most deplored. Unfor-
tunately information concerning this species is entirely wanting
in all his publications. The fact that certain correspondence
passed between him and the Austrian algologist, Dr. Lutkemuller,
shows that he was in some doubt about the species. Dr. Lutke-
muller had examined all the exsiccate of supposed St. pilosum
that he possibly could, and it is clear from a perusal of the cor-

* The writer is of the opinion that it is very doubtful whether the Desmid
figured by Wittr. (' Skand. Desm.' 1869, 1. 1, f. 8), really was St. pilosum, since it
agrees more nearly with St. hirsutum in the form of its semicells. In that case
the figure of the zygospore given by Wittrock and reproduced on PL CXXXVIII,
f. 2, may not be correct for St. pilosum. This zygospore is, indeed, very similar
to Lutkemuller 's figure of the zygospore of St. hirsutum (cf. PL CXXXVIII,
f. 6).

STAURASTRUM. 65

respondence between the two algologists that Dr. Liitkemiiller
considered all the specimens of so-called St. pilosum he had ex-
amined to be without exception either St. hirsutum or St. muri-
catum. Thus Dr. Liitkemiiller came to the conclusion that no
one knows what St. pilosum Nag. really is, and he was accord-
ingly very doubtful about its being a valid species. Whether
Professor West agreed with Dr. Liitkemiiller on this point is not
certain. A particular alga first identified amongst his records
as St. pilosum was later altered to St. Brebissonii, but the date
at which the alteration took place is not known. The specimens
in question have been examined and they are very similar to
PL CXXXVIII, fig. 3. The actual specimen there figured was
taken from a collection from Esher West End Common, and
identified by Professor West as St. pilosum Nag. Professor West
left only one drawing of St. pilosum. and a rough freehand draw-
ing of the vertical view. These are reproduced on PI. CXXXVIII,
fig. 1. From these and from certain other rough sketches it
would seem that Professor West's original idea of St. pilosum was
that it should be similar in size to St. hirsutum Breb., but that
its semicells should be narrowly elliptical rather than tnmcate-
pyramidate as in that species, and its spines should be some-
what longer and more delicate. In vertical view the lateral
margins are distinctly concave. Liitkemiiller was of the opinion
that Nageli's original figure of St. pilosum merely represents
a smooth Staurastrum in which the pore threads had hardened
and were distinctly visible.

88. Staurastrum hirsutum (Ehr.) Breb.
(PI. CXXXVIII, figs. 4-6.)

Xanthidium hirsutum Ehr. Org. kl. Rauin. 1834, p. 318 ; Menegh. Svn.

Desm. 1840, p. 223 : Kiitz. Spec. Alg. 1849, p. 177.
Euastrutii hirsutum Kiitz. Phyc. Germ. 1845, p. 137.
Staurastrum muricatum Ralfs in Ann. Mag. Nat. Hist. 1845 (in part), t. 11,

f. 1, a, 6, and c.
St. hirsutum (Ehr.) Breb. in Ralfs, Brit. Desm. 1848, p. 127, t. 22, f. 3 ;

Rabenh. Krypt.-fl. Sachs. 1863, p. 190 ; De Not. Desm. Ital. 1867, p. 50,

t. 4, f. 41 ; Rabenh. Flor. Europ. Alg. 1868, p. 211 ; Kirchn. Alg. Schles.

1878, p. 166 ; Wolle, Desm. U. S. 1884, p. 141, t. 45, f. 19-21 (accuracy

very doubtful) : Cooke, Brit. Desm. 1887, p. 149, t. 52, f. 1 ; Hansg.

Prodr. Algenfl. Bohmens, 1888, p. 214; De Toni, Syll. Alg. 1889, p. 1165 ;

Heimerl, Desm. alp. 1891, p. 605 ; West, Alg. W. Ireland, 1892, p. 174 ;

Alg. Engl. Lake Distr. 1892, p. 19 ; Racib. Desm. Ciast. 1892, p. 389 ;

Roy & Biss. Scott. Desm. 1893, p. 21 ; West & G. S. West, Alg. S. England,

1897, p. 494 ; Alga-fl. Yorks. 1902, p. 100 ; Alg. N. Ireland, 1902, p. 48.
Phycastrum apkulosiun Ktitz. Spec. Alg. 1849, p. 182.

VOL. V. 5

ti<i BRITISH DESMIDIACE^E.

stniirn*innn ailesiocum Hil.se in Rab. Alg. Eur. no. 1826.
St. muricolum Nordst. Desm. Bornh. 1888, p. 203, t. 0, f. 19-22.
,v/. ,,;/..*///// 1. minor \\'ittr. & Nordst. Alg. exsic. iios. 1474 & 409 (f. minor
Bee, I'r. .1. Liitkrmiillrr).

CVlIs .small, up to 1| times longer than broad, deeply
, . »ns1 nVtcd. sinus narrow, nearly linear for some distance,
tl ifii opening more widely; semicells subpyramidate-
trimcate, subreniform or even subsemicircular, usually
\\ idest near the base, angles broadly rounded ; cell- wall

< ovcml with delicate hair-like spines arranged in con-

J_ C-J

< -en trie series round the angles. Vertical view triangular,
sides nearly straight, rarely very slightly convex or
C( >ncave, angles obtusely rounded, centre of apex smooth.
( liloroplast axile, with a central pyrenoid in each semi-
cell.

Xygospore roughly spherical, but somewhat angular,
I rovided with numerous stout processes repeatedly
forked at the apex.

Length, without spines, 34-44 ;JL ; breadth, without
-pines, 31-35 \L ; breadth of isthmus 10-13 [j. ; length
of spines 1*5-2 pi; diam. zygosp., without processes,
38|JL ; with processes, 69 JJL.

KXCLAND. Cumberland ! Westmoreland ! Lanca-
shire ! (Ralfs). W. and N. Yorks ! Leicester (Roy).
Kssex! Warwicks (Witts). Worcester! Surrey! Sussex
i/.V/.v). Kent! Hants! (Bennett). Devon! (Harris).
( 'ornwall !

WALES.— General !

SCOTLAND.— General ! (Roy. & Biss.). Orkneys ! Shet-
lands! Rare in the plankton !

I RELAND.— Donegal ! Mayo ! Galway ! Kerry ! Shores
of Loiio]] Ncagh ! Dublin and Wicklow (Arch.). Down !

Geogr. Distribution.— France. Germany. Switzerland.

Galicia and Austria. Hungary. Eoumania. Italy.

Norway. Finmark. Sweden. Denmark.

Bomholm. Faeroes. Spitzbergen. Greenland. United

tat.-. Colombia. Brazil. Paraguay.

St. hirsutum is distinguished from all allied species by the form
which are always wider at the base than else-

STATJBASTRUM. ,;7

where, the basal margin being almost straight, and the sinus
in consequence quite narrow. Some forms with shorter spines
are very similar to St. muricatum Breb., and it is often difficult
to draw a sharp line between the two species. St. muricai»m
is usually larger than St. hirsutum, and its spines are much
shorter.

89. Staurastrum muricatum Breb.
(PI. CXXXVIII, fig. 9; PL CXXXIX, figs. 1, 2.)

BiiiattUa muricatum Breb. Alg. Falaise, 1835, p. 2(39.

Staurastrum muricatum Breb. in Menegh. Synops. Desm. 1840, p. 22(i (in

part) ; Ralfs, Brit. Desm. 1848, p. 126, t/22, f. 2 ; Arch, in Pritch. Inf.

1801, p. 740; Rabenh. Krypt.-fl. Sachs. 1863, p. 190; De Not. Desm.

Desm. U.S. 1884, p. 127, t. 42, f. 3, 4; Cooke, Brit. Desm. 1887, p. l.V.»,
t. .14, f. 5; De Toni, Syll. Alg. 1889, p. 1189; Heimerl, Desm. Alp.
1891, p. (505 ; Liitkem. Desm. Attersees, 1893, p. 566 ; Roy & Bi<s.
Scott. Desm. 1893, p. 22 ; West & G. S. West, Alg. S. England, 1897,
p. 494 ; Comere, Desm. de France, 1901, p. 175, t. 12, f. 7 ; West &
O. S. West, Alga-fl. Yorks. 1902, p. 102 ; Alg. N. Ireland, 1902, p. 50 ;
Gutw. Alg. Mont. Tatrensium, 1909, p. 472 ; Borge, Botan. Xotis. 1913,
p. 29.

Xanthidium deltoideum Corda, Aim. de Carlsbad, 1840, p. 214, t. 5, f. 38, 39.

tloniocystis (Trigonocystis) muricata /3 rugosa Hass. 1845, p. 19, t. 84, f. 10.

titaurastrum muricata /3 Ralfs in Ann. Mag. Nat. Hist. 1845, p. 154, t. 11,
f. 1, d and e.

Phycastrum muricatum Kiitz. Spec. Alg. 1849, p. 182.

Phycastrum (Amblyactinium) muricatum Xag. Gatt. einz. Alg. 1849, p. 125.

Cells of medium size, about 1-J times longer than broad,
rarely Ij times longer, deeply constricted, sinus narrow,
but opening more widely; semicells subeUiptical or
reniform, sometimes truncate-pyramidate, dorsal margin
much more convex than the ventral, angles obtusely
rounded . Cell- wall covered with minute conical granules
arranged in close concentric series round the angles
Vertical view triangular, sides straight or very slightly
convex, angles obtusely rounded, granules in the centre
of the apex often reduced or wanting. Chloroplast
axile, with a single pyrenoid in the centre of each semi-
cell, and a pair of lobes extending into each angle.

Zygospore unknown.

<;S IJIUTISH DESMIDIACE^E.

Length 4(i <tf'5[jL : breadth 40-55 (JL ; breadth of
i>t Inniis |-J '2\ [i.

Kx< ; LA \ i >.- -Cumberland ! Westmoreland ! W. and
N.Yorks! Kssex! Warwicks! (TF*). Surrey! Sussex
(AW/*). .Hunts! Devon! (Harris). Cornwall! (Mar-
quand).

\\ A L i > -Fairly general !

SCOTLAND.— Sutherland, Ross, Inverness. Aberdeen
(at :j;>uO feet on Lochnagar !), Kincardine, Forfar,
IVrth! Argyle, Arran (Roy & Biss.). Dumbarton
(C(ti'U'i'). Kircudbright ! Orkneys ! Shetlands !

I RELAND.- -Donegal ! Clare Island and Inishturk Isle,
Mavo ! (Jalwav ! Kerry ! Down !

* »/ *

Geogr. J Distribution- -France. Germany. Switzerland.
(Jalicia and Austria. Hungary. Italy. Norway. Sweden.
|)riiniark. Bornholm. Finland. Faeroes. Australia
(var.). I'nited States and Alaska.

N/. murieatum is very widely distributed in the British Isles.
It is closely allied to St.hirsutum, from which it is distinguished
liy its usually larger size and much shorter spines, which
;uv, a< a rule, reduced to small conical granules. Intermediate
forms between the two species are, however, not unknown.

DO. Staurastrum pyramidatum West.
(PL CXXXVI1I, figs. 10-12; PL CXXXIX, fig. 16.)

Shiiii-iixtrinn in in-ir, iinn, lorma West, Alg. X. Yorks. 1889, p. 293.

nuricatum var. acutum West, Alg. X. Wales, 1890, p. 294, t. 5, f. 14;.
Him. Desm. Filmland, 1903, p. 22.

,N7. iujrnin'iihiliini West. AI-. W. Ireland, 1892, p. 179; Alg. Engl. Lake Distr.
I2,p.20; Alg. aq. dulc. Lusitan. lS92,p. 1.103; West & G. S. West, Alg.
. England, IS'.»7. p. 4tt4 ; Outwin. Karlsbad Algen, 1899, p. 6 ; West &
West, Alga-fl. tforks. 1902, p. 103 ; Alg. N. Ireland, 1902, p. 51.

<VHs of medium size, 1^-U times longer than broad,
< I reply constricted, sinus usually almost linear, rarely
>ll.-lltl> "I"'11 : semicells broadly pyramidate, apex
Bubtruncate, sides slightly convex, basal angles obtusely
rounded; cell-wall covered with stout acute conical
spines, arranged in concentric series round the angles,
"ining more scattered and sometimes emarginate on

STAURASTRUM. ()!)

the apex, the centre of which is usually smooth. Ver-
tical view triangular, sides straight, "angles obtusely
rounded. Chloroplast axile, with a central pyrenoid in
each semicell, and a pair of plates extending into ea«-li
angle.

Zygospore large and spherical, provided with numerous
short stout processes, repeatedly branched at the apex.

Length 60-84(1 ; breadth 52-57 [i ; breadth of isth-
mus 16-18 [i ; diam. zygosp., without appendages, 57 ;i ;
with appendages, 80 JJL.

ENGLAND. — Scawfell, Cumberland (with zygospores) !
Bowness and Helvellvn, Westmoreland ! Cocket Moss,

«/

near Giggleswick, Cautley Spout and Penyghent, W.
Yorks ! Mickle and Cronkley Fells, N. Yorks ! Keston
Common, Kent ! Dartmoor, Devon ! Near St. Just,
Cornwall !

WALES. — Snowdon, Llyn Iclwal and Yr Orsedcl, Car-
narvonshire !

SCOTLAND. — Scourie, Sutherland ! Glen Tilt, Perth !
Wigtown !

IRELAND.— Carrantuohill, Co. Kerry ! Slieve Donard,
Down (at 2000 feet) !

Geogr. Distribution.— Germany . Portugal . Finland.
K. Africa.

St. pymmidatu-m is distinguished from St. muncatiun by the
more definitely truncate-pyramidate form of its semicells, and
by its more robust conical spines. It is a common species in
upland boggy districts. St. trapezicum Boldt, var.
spinosum Schmidle (in ;Hedwigia,' 1895, p. 81, t. 1, f. '25), is
probably a form of this species.

Var. coilon West. (PL CXXXVIII, fig. 13.)

St. pymmidatum var. coilon West & G. S. West, New Brit. Freslnv. Alg.
1894, p. 11, t. 2, f. 46.

This variety differs from the type in its more numerous
granules ; in the vertical view the lateral margins are
furthermore concave, and the angles subacute.

Length, without spines, 72 -5 [i ; with spines, 80 y.;

7(> BRITISH DESMIDIACE^E.

l.ivjulth. without spines, 60 [i ; with spines, 65 [i ; breadth
of isthmus 17'5{JL.

SCOTLAND.— Corrie Ceandor, Perth !

(.»1. Staurastrum Ravenelii Wood.
(PI. CXXXVITI. figs. 7, 8.)

St. /.'"<•< nelii Wood, Freslnv. Alg. N. Amer. 1873, p. 153, t. 21, f. 22 ; Wolle,
Desm. I . S. 1SS4, p. 143. t. 45, f. 17, 18, t. 52, f. 7, 8 ; De Toni, Syll.
Alg. 1889, p. I 17-J : \\Vst \- G. S. West, Some Desm. U. S., 1808, p. 312.

Si. Tri U«-h use Turn. Desm. Notes, 1893, p. 345, f. 12 ; Nordst. in Wittr.
\ \..r«Ut. Al.tr. exsic. no. 1477, and fasc. 35, 1903, p. 11.

Cells small, about as long as broad or a little longer,
dreplv constricted, sinus linear for some distance, then
• .pi'iiing more widely; semicells subelliptical or sub-
reniform. or even subpyramidate - truncate, dorsal
mnruiii much more convex than the ventral, basal angles
broad I v rounded. Cell- wall provided with conical
i:r; mules, arranged in rather distinct concentric circles
round the angles, and sometimes becoming emarginate,
about 8 or 9 rows visible across the face of the semicell.
Vertical view triangular, lateral margins nearly straight,,
granules wanting in the centre of the apex.

Xyii'ospore unknown.

Length 28-36 p ; breadth 28-32^ ; breadth of isth-
mus 8-14(i.

WALES.— Trelleck Common, Monmouth (W. B. Turn.).
Distribution. -Sweden. United States.

It is si i M ;,_,-, .sted amongst the notes of the late Professor West that
. Ti-rHrckmse Turn, is synonymous with St. Ravenelii Wood.
Although the figures of Wolle, Wood, and Turner are all poor,
certain similarities are evident, for they seem to represent a small
Stawastrum with oval or elliptical semicells, lateral angles
broadly rounded, and with the cell-wall covered with acute
< cincal granules (The error in Wolle, ' Desm. U. S.' 1884, t. 45,
is pointed out by the author himself.) The alga distri-
buted in Wittr. cV- Xnrdst, ' Alg. Exs.' no. 1477, as a form of
Tretteckense Turn, seems to differ in several points from the
plant Bgurecl l.v the above authors, cf. PL CXXXVIII, figs. 7, 8.
semicells are more depressed, and instead of being more

STAURASTRUM. 71

or less oval they are subhexagono-trapezoid. The sinus is also
somewhat narrower. The real characters of St. Ravenelii and
St. Trelleckense are, however, still imperfectly known.

92. Staurastrum erasum Breb.
(PL CXXXVII, figs. 9-11.)

St. erasum Breb. Liste Desm. 1856, p. 143, t. 1, f. 28 ; Rabenh. Flor Eurm
Alg. 1868, p. 212 ; De Toni, Syll. Alg. 1889, p. 1147 ; Roy & Biss. Scott
Desm. 1893, p. 19: \\est & G. S. West, Notes Alg. IL 1900 p. 2!»ii •

/""*1 ^ T\ 1 T^ ^ f\f\ "1 T /"» A t f^ n

Phytoplankt. 1909, p. 202 ; Gronblad, Desm. Keuru, 1920 p 6? t
f. 92-94.

•-<(. Brebissonii var. ordination Schmidle, Lappmark Siiss-vrasserak'en, 1898
p. 53, t. 3, f. 1.

Cells small, about as long as broad, deeply constricted,
sinus acute, widening rapidly outwards ; semicells sub-
elliptical, ventral margin much more convex than the
dorsal, which is subtruncate ; angles broadly rounded,
and slightly retuse ; cell-wall thickly covered with
short spines arranged in concentric circles round the
anoles, where thev are longest, and becoming very much

C? «/ v

reduced towards the centre of the faces. Vertical view
triangular, sides concave, centre of apex nearly or quite
smooth.

Zygospore unknown.

Length, without spines, 30-42 [i ; breadth, without
spines, 30-42 ^ ; breadth of isthmus 10-11 [i; length
of spines at the angles, about 1'opi.

ENGLAND.- -Plankton of Hayes Water, Westmore-
land ! Risley Bog, Lancashire (Roy).

WALES.— Glyder Fach (at 2200 feet), Carnarvonshire !
In the plankton !

SCOTLAND.— Near Coul, Ross (Roy & Biss.). Loch
Ruar, Sutherland ! L. Ghorma, Inverness ! Loch-
nagar, Aberdeen (up ' to 3500 feet) ! L. Doon, Ayr !
Plankton of Lochs Brindister and Beosetter, Bressay,
Shet lands !

Geogr. Distribution .- -France. Germany,
(form). Finland. Siberia. United States (var.).

7-> HIMTISH DESMIDIACE.E.

St. erasum \* distinguished from St. Brebissonii by its more
numerous and usually shorter spines, and it also differs in the
shape «•!' its semicells. the apex being almost flat, and the semi-
cells widest ill this region.

Staurastrum erostellum W. & G. S. West.
(PL CXXXVT, fig. 12.)

-/. rostellum var. crostdlntn West & G. S. West, Alg. S. England, 1897,

P. 4 «.»:}. t. ii, t. 18.
St. erostellum \V. & G. S. West, Notes Alg. II, 1900, p. 296.

Cells small, about as long as broad, deeply constricted,
sinus acute angled and widely open ; semicells inverted
subreniform, apex nearly straight or slightly convex ;
• •••ll-wnll covered with short stout spines arranged in
concentric series around the angles, and rather longer
;it the angles than elsewhere. Vertical view triangular,
lateral margins slightly concave, angles somewhat
rounded.

Zygospore unknown .

Length, without spines, 19*5 [JL ; breadth, without
-pines. l(.)'5(ji. ; breadth of isthmus 6*5 [JL.

KXGLA:NI>. -Thursley Common, Surrey !

Sf. ifnsirUmn differs from St. cosmospinosum (Borg.) W. &
G. S. West (=St. rostcllum Roy & Biss.) in its smaller size, its
d«'«-]MT constriction and different form of the semicells, in the
:d>sriic»' of the large spine at the angles of the semicells, and also
in the triangular vertical view with more rounded angles.

The relative size, number, and arrangement of the smaller
-I'liirs is the same as in St. cosmospinosum, although in the
latter -|>.-ries they do not increase in size towards the angles.

Kriteh (• Krrslnv. Alg. Madagascar,' 1914, p. 51) has suggested
that this species may be a form of St. clavifertim W. & G. S. West

Sorth American Desm.' 1895, p. 259, t. 16, f. 25). In this
., however, the shape of the cell is quite different.

STAURASTRUM. 73

SECTION G.

Cells with verruca? which are emarginate, or very much reduced
and 2- or 3-spmate.

; Cells more than 1| times longer than broad.

t Lateral margins with an incision or rounded concavitv •
semicells angular.

94. St. at:n, -ill as.
TT Lateral margins entire ; semicells subelliptic.

95. St. aspenui'.
Cells about as long as broad or only slightly longer.

t Verruca restricted to the angles and apex ; faces of
semicell smooth.

96. St. maamense.
ft Verrucas more or less evenly distributed.

J Verrucae surmounting distinct though short pro-
cesses pushed out from the cell- wall.

97. St. spongiosum.
Jf Verrucse borne directly on the cell-wall.

98. St. echinodermum.

99. St. Amelia.

100. St. scabrum.

101. St. subscabrum.

94. Staursatrum acarides Xordst.
(PL CXL, figs. 6, 7.)

•S7. <i.<:arides Xordst. Desm. Spetsb. 1872, p. 40, t. 7, f. 26; Joshua. Note-
on Brit. Desm. II, 1883, p. 292 ; Cooke, Brit. Desm. 1887, p. h>3. t. 60,
f. 5; De Toni, Syll. Alg. 1889, p. 1169; West, Alg. X. Yorks. 18N1».
p. 293 ; Roy & Biss. Scott. Desm. 1893, p. 16 ; Borge, Siisswasseralgen
Franz Josefs-Land, 1899, p. 764.

Cells rather under medium size, about l:i times longer
than broad, oblong elliptic in outline ; constriction
moderately deep, sinus linear, dilated at its apex, semi-
cells pyramidate-truncate, somewhat angular, apex
broad and truncate, or often slightly concave, basal
angles almost rectangular, upper angles obtusely
rounded, lateral margins verrucose, with a small rounded
concavity just above the middle part ; semicells in front
view with several short longitudinal series of verruca*,
rather more crowded towards the angles. Vertical view
triangular, sometimes hexangular, lateral margins verru-
cose and slightly convex, angles bluntly rounded, with

71 BRITISH DESMIDIACE^.

i> or :5 concentric series of verrucsc around the middle of
the apex, the actual centre being smooth.

X\ -os pore unknown.

Length 40-48 [Ji ; breadth 30-34 (JL ; breadth of apex

IT-:. -JO;/..

ENGLAND- -Penyghent and Mickle Fell, N. Yorks !

SCOTLAND.— Craig Phiobaidh near Girnoc and Corrie
cf Loch Ceanmhor, Aberdeen; Canlochan, Forfar; Alva
(iliMi. Stirling (Roy & Biss.).

Geogr. Distribution.— Norway. Sweden. Faeroes.
Nova Zembla, Spitzbergen. W. Greenland.

The British examples differ from the original specimens from
Spitzbergen in their proportionate greater length and in the
convex sides in the vertical view. They also seem to be more
Mnmuly \Trrucose.

Yar. eboracensis West. (PL CXL, figs. 8-10.)

St. n,;iriih-* var. eboracensis West, Alg. X. Yorks. 1889, p. 273, t. 201, f. 8 ;
\\t-t ,V G. S. West, Alga-fl. Yorks. 1902, p. 106.

Differs from the type in its deeper lateral incisions,,
which are almost linear.
Dimensions as in the type.
KN< ; LA XD.— Mickle Fell, N. Yorks !

95. Staurastrum asperum Breb.
(I'l. CXL. figs. 11-13; PL CXLI, fig. 21.)

,v/'/'//v/.x//-///,, asperum Breb. in Ualfs, Brit. Desm. 1848, p. 139, t. 22, f. G,
t. 2:5. f. 12 a : Arch, in Pritch. Inf. 18(51, p. 740; Rabeuh. Flor. Europ.
AI-. isr.s. ,,. -Jd'.i : Ci.Dke, Brit. Desin. 1887, p. 154, t, 53, f. 4 : De Toni,
Syll. Alg. lssi», p. 117.-): |{,,y & Biss. Scott. Uesm. 1893, p. 179: West
A- G. S. West, X<-\\ Brit. Freshw. Alg. 1894, p. 11, t. 2, f. 48; Comere,.
Desm.de l-'ram-r, I'.ml, p. KJO, t. 12, f. 27.

l>i'h/nii<litti,, (Xtii/ir.i*/nnn) iixj^ntnt Reinsch, Algenfl. Frank. 1867, p. 160.

I VI Is i-jitlicr under medium size, about li times longer
than broad, deeply constricted, sinus open and nearly
rectangular : semicells broadly elliptical, widest towards
tho apex, dorsal margin much less convex than the
ventral, aii^los broadly rounded; peripheral margin

STAURASTRUM. 75

with about 18-20 granules, the apical ones more or less
flattened or emarginate, granules in front view of semi-
cell arranged in about 7 longitudinal rows, the median
row incomplete, and the uppermost granule of each row
larger and emarginate. Vertical view 3-5-angular, sides
straight and granulate, angles broadlv rounded and

»/

bearing a few spines longer than the rest, with a curved
series of about 6 emarginate granules within each lateral
margin ; centre of apex smooth.

Zygospore orbicular, spines twice branched at the
apex.

Length 42-52 u ; breadth 34-47 <j. ; breadth of isth-
mus 12-1 5 p» ; diam. zygosp.. without processes, 47'5[JL ;
with processes, 75 u.

ENGLAND.- Westmoreland! (Bissett). N. and K.
Yorks! Lancashire! Leicester (Roy). Warwicks (Witts).
Gloucester (Ralfs). Surrey ! Sussex (Ralfs). Hants !
Devon (Harris) ! Cornwall !

WALES.— Capel Curig and Llyn Tdwal, Carnarvon-
shire ! Ffestiniog, Merioneth !

SCOTLAND.— Sutherland, Ross, Aberdeen, Kincardine,
Forfar. Perth and Fife (Roy & Biss.). Loch Shiel,
Inverness ! Orkneys ! In the plankton !

IRELAND.— Clare Island, Mayo ! Xear Oughterard and
Ballynahinch. Co. Galway ! CarrantuohilL Co. Kerry
Dublin and Wicklow (Arch.). Munster, Leinster and
Connaught (Adams).

Geogr. Distribution.- -France. Germany. Gahcia and
Austria. Sicilv. Sweden. Faeroes. United States.

*/

96. Staurastrum maamense Arch.
(PL CXXXIX, fig. 10.)

St. maamense Arch, in Quart. Journ. Micr. Sci. vol. I'. 18(jJ». P.*'": ^oke,
Brit. Desm. 1887, p. 155, t. 53, f . 3 ; De Tom, Syll. ; l175 '

West, Alg. W. Ireland, 1892, p. 176 ; Roy & >- ; ;./ ;

p. 184 ; West & G. 8. West, Some X. Amer. Desm.
Freshw. Phytoplankton, 1909, p. 202. ,, ,

St. pseudocrenatum Lund. Desm. Suec. 1871, p. bo, t.
Alg. U. S. 1887, p. 42, t. 57, f. 9, 10.

7»i milTlsH DESMIDIACEJE.

Cells -mall, as long as broad, or sometimes a little
longer ilmn l>n>ad, broadly oval or circular in outline,
di'cplv constricted, sinus very narrow and linear; semi-
••ells nearly .-emicircular or subpyramidate-truncate,
ventral margin straight, dorsal margin somewhat flat-
tened on the apex, lateral margins with about 4 emar-
i:inate verruca?, which are seen when the angle is viewed
from ih<' front as a series of broad complicated verrucas
extending from the apex to the base of the semicell ;
upper margin of faces with an apical series of verrucas.
Yertiral view triangular, lateral margins concave, angles
luoadly truncate and tricrenate, with two or three series
oi verrucas just within the truncate angles, and another
series just within the concave margins.

/VIM »s] x >re unknown.

Lt-n-tli 33-42 IJL ; breadth 30-35 (i ; breadth of isth-
mus Ilia.

K x < ; i , A x i ) . Xear Bowness, Westmoreland (Bissett) .

SCOTLAND.- -Powlair, Rosehill Loch, Craigendinnie,
M«»s of Logic, Loch Da wan, Aberdeen; Craithes, Kin-
eanline ; near Tobermory in Mull, Argyle (Roy & Biss.).
Moidart. Inverness !

1 1 : K LA N i > . -Ballynahinch ! , Derryclare Lough ! , plank-
t«-n <>f Loti'Ji Corrib! and near Maam (Archer), Gal way.
. Co. Cork !

Dixtrihntitni- Norway. Sweden. Finland.
United States.

• >7. Staurastrum spongiosum Breb.
(PI. CXL, fig. 14.)

'mil, II, i .v/»;//f//«,.sv/ lin'-l>. in Cheva]. inirroscop. et usage, 1839, p. 272.

'tauraatrum .«II<>,,,/;<,«U,H Breb. in Halts, Brit. l)e.sm. 1848. p. 141, t. 23, f. 4 ;

\><h. in IVit.-h. Int. 1X01, j). 739, t. 3, t. 22, 23; Rabenh. Krypt.-fl.

Sachs. lsi;:{, ,,. |'.i;{: n«. \()t. ivsni. Ital. lS(i7, p. 48; Rabenh. Flor.

Km. Alg. 1868, ]>. 2)7 ; Lund. De.-sin. Suer. 1871, p. (35; Nordst. Norges

1873, |.. 32 ; Kirclm. Alir. Scliles. 1878, p. 100; Turn. New Rare

85, p. f.. t. l.\ L 22 ; ( 'onke, Brit. Desm. 1887, p. 153, t. 53, f. 1 ;

Desm. Cn.nland, 1888, p. 3i> ; West, Desm. Massach. 1889, p. G,

I'- Toni, S\ll. Al.u. 1889, p. 1174; Racib. Desm. Ciaston. 1892,

AI.L'. \\. Ireland, 1N92. p. 175; Roy & Biss. Scott. Desm.

26; \\ esl & G. S. \V<-st, Alir. S. tlngland, 1897, p. 494; Schmidle,

STAUBASTRUM. 77

Lappmark Siisswasseralgen, 1898, p. 54; Cumere, Desm. dc France
1901, p. 169, t. 12. f. 10 : Him.. Desm. Finnland, 19o:!, p. L':: : Cushman
in Rhodora, 1905. p. 204; Teodoresco, Alg. Roumania. I'.xiy, p. i
Borge, Botan. Xotiser, 1913, p. 50 ; Kaiser. Alg. Traunstriii. I'.M 4. p. i

Asteroxanthium ramosum Kiitz. Spec. Alg. 1849, p. 184.

Didymidium (Staurastrum)6pongiosumT&eiiisch,A]gevS.. Frank. LSiiT. p. 17.",.

Staurastnnn megalonotum forma fiastata Schmidle, Beitr. \ln \lir Is
p. 35, t. 17, f. 6, 7.

Cells rather under medium size, about as long as broad,
or a little longer, roughly circular in outline, deeplv
constricted, sinus narrow, sometimes almost linear :
semicells subsemicircular or subpyxamidate- truncate in
outline, basal angles obtuse and ending in a short
verrucose process ; about 8 or 10 emarginate processes
visible round the periphery, and 6 others forming a
curved series across the face of the semicell. Vertical
view triangular, sides usually slightly convex, angles
ending in a short verrucose process, each lateral margin
with 6 emarginate processes, and 3 similar pairs arranged
across each angle, decreasing in size towards the angles :
centre of apex smooth.

Zygospore spherical, furnished with numerous spines
once or twice dichotomous at their apices (Lund.).

Length 45-53 JJL ; breadth 42-50 JJL ; breadth of isth-
mus 12 jjt ; diani. zygosp., without processes, 56 n ;
length of processes 24 [i .

ENGLAND.— Cumberland ! Mickle Fell, Vorl
Warwicks (Wills). Surrey! Sussex (Ralfs). Hants
(Bennett). Devon ! Cornwall !

WALES.- -Bethesda !. Dolbadarn Castle I, Llyn Padara !
and Capel Curig! (Cooke & Wills), Carnarvonshire.
Dolgelly, Merioneth (Ralfs).

SCOTLAND.-- Sutherland, Boss, Inverness, Aberdeen.
Kincardine, Forfar !/ Perth!, Argyle and Stirling;

(Roy ci1 Biss.).

IRELAND.— Ballvnahinch, Galway ! Carrantuoh
Kerry! Adrigole, Co. Cork! Dublin and Wicklow

(Arch.).

Geogr. Distribution.- -France. Germany.
Galicia and Austria. Hungary.
Portugal. Norway. Sweden. Finland. Poland

7S r-IMTlSH DESMIDIACE.E.

Iliissj;!. Spit/beru'en. Greenland. Siberia, United States.

Ar_M'iit inc.

.s1/. sfi.nni'iox'im is a beautiful species, and is very well charac-
t.-ri-i'.l l>y its |)rominent and regularly arranged verrucae, which
are <«> l.-ir^e as almost to constitute short processes with emar-
LMiiat.- apices. The front view naturally varies in appearance
according as the individual is observed from the face view or
tin1 anide.

Var. perbifidum West. (PI. CXL, fig. 16.)

St. spongiosum var. perbifidum West, Alg. W. Ireland, 1892, p. 175, t. 23,
f \\ • Uitk. Desin. Attersees, 1893, p. 365, t. 9, f. 15; Schmidle, Beitr.
Alp. Alir. is!»r,, p. 32 ; W. & G. S. West, Alg. S. England, 1897, p. 494 ;
li.ir-j. Alg. Faeroes, 1901, p. 234; Borge, Botan. Notiser, 1913, p. 50.

This variety differs from the type in that the granules
<»t the emarginate processes are developed into stout
spines.

I )imensions as in the type.

lv\( : LAND.- -Borrowdale, Cumberland ! Thursley Com-
mon. Surrey (3- and 4-ended forms) !

I I:K LAND.- -Near Westport, Co. Mayo !

('<'n<j ,- . Distribution. — Germany. Austria. Sweden.
Faeroes.

Transitional forms between this variety and the type form are
frequent.

Var. Griffithsianum (Nag.) Lagerh. (PL CXL, fig. 15.)

/'/////•'/.•*//•///// (/W///./f7////>////) Criffithsianum Xag. Gatt. einz. Al». 1849,
p. I2S, t. S. ('. f. L>.

Staurastrum Uriflithximnuii Aivh. in Quart. Journ. Micr. Sci. 1866, p. 67;
Cookr. Brit. Dcsm. 1887, p. 154, t. 53, f. 2; Georgev. Desm. Wlasina

L909 p. 203.

x/. spongiosum var. ^'/-///f///.</V/ «///// Lagerh. in Wittr. & Nordst, Alg. exs
1886 : DC Tmii, Syll. Alg. 1889, p. 1174 ; Liitkem. Desm. Atter-
.'.'{. p. ~n»4 ; Borge, Botan. Notiser, 1913, p. 50.

'11s with the sinus open towards the exterior, sides

in the end view nearly straight or slightly concave, with

deep mimded and prominent concavity between the

two MHMlmii processes of each lateral margin ; in other

characters similar to the type. In the development of

spines this variety resembles var. perbifidum West.

STAURASTRUM. 7<)

Dimensions as in the typical form.

ENGLAND.— Dartmoor, Devon (Harris).

WALES.— Capel Curig and Dolbadarn Castle, Carnar-
vonshire !

Geogr. Distribution.- -Finland. Germany. Switzer-
land. Galicia and Austria. Servia. Sweden. Spitz-
bergen. Greenland. Sandwich Isles.

Bennett in 'Freshw. Alg. Engl. Lake Distr.' II, 1888, p. 6, 1. 1,
f. 15, 16, has described a var. cumbricum of this species, but
his figures and diagnosis are insufficient. It is not impossible
that Bennett's variety is identical with the var. perbifidum of
West.

98. Staurastrum echinodermum W. £ G. S. West.
(PI. CXXXIX, figs. 8, 9.)

*S7. echiHoderniiiHi West & G. 8. West, Notes Al£. Ill, 1903, p. 11, t. 44(3,
f. 13.

Cells small, slightly longer than broad, deeply con-
stricted, sinus open and acute angled ; semicells angular
but roughly elliptical, angles subtruncate, dorsal margin
strongly convex, angles and apex with a series of about
8, often emarginate, spines, faces of semicell with two
transverse series of spines ; vertical view 4- or 5-angular,
sides very slightly concave, angles acutely rounded,
margins armed with short spines, and with 2 emarginate
spines within each lateral margin.

Zygospore unknown.

Length, without spines, Sl'Sfi; breadth, without
spines, 27 pi ; with spines, 30'8 ji ; breadth of isthmus
lO'o fz.

WALES.— Glyder Fawr (at 2700 feet), Carnarvonshire !

99. Staurastrum Arnellii Boldt.
(PI. CXXXIX, figs. 11-14.)

Staurastrum Arnellii Boldt, Sibir. Chlorophyc. 1885, p. 112
De Toni, Syll. Alg. 1889, p. 1170; West & G. S. West, -Notes
1900, p. 297, t, 412, f. 15-18; Alga-fl. Yorks. 1902, p 103 ; Ah
Ireland, 1902, p. 51 ; Brit. Freshw. Phytopl. 1

80 BRITISH DESMIDIACE.E.

Cells small, 1 J- times longer than broad, deeply con-
stricted, sinus narrow, sometimes linear ; semicells
pyramidate- truncate, ventral margin straight, apex
truncate, sides slightly convex, upper angles very obtuse,
basal angles broadly rounded, peripheral margin denti-
culate, showing about 26 or 28 granules, those near the
basal angles sometimes developing into short spines ;
faces of semicell granulate near the margin, granules
arranged in 2 or 3 concentric series round the basal
angles, and in about 3 series parallel to the apical
margin, the latter being emarginate ; granules in the
middle of the faces becoming smaller and scattered,
centre of face almost smooth. Vertical view triangular,
angles obtusely rounded, sides very slightly concave,
margins denticulate, those granules in the middle of
lateral margins being emarginate; angles with two or
three concentric series of denticulations, and with
two pairs of emarginate verrucee within each lateral
margin.

Zygospore unknown.

Length 30-38'5u; breadth 31-38'5(Ji; breadth of
isthmus 9'5-12[jL.

ENGLAND.— Mossdale Moor, Widdale Fell, N. Yorks !

WALES.- -Y Foel Fras, Carnarvonshire !

IRELAND. --Near Gweedore, Co. Donegal !

Geogr. Distribution . — Siberia .

Var. inornatum Rov.

•>

St. Amellii var. inornatum Roy, Desm. Alford District, 1890, p. 208 ; Roy &
Biss. Scott, Desm. 1893, p. 'l7.

Differs from the type in the granules being scattered.
SCOTLAND.- -Very rare, near Alford, Aberdeen (Roy
Biss.).

Var. spiniferum W. & G. S. West, (PL CXXXIX,

fig. 15.)

St. Arnellii var. spiniferum West & G. 8. West, Al<?. N. Ireland, 1902, p. 51r
t. 2, f. 38.

STAURASTRUM. 81

Cells not so angular as in the type, sinus a little more
open, and distinctly swollen at the apex ; a few of the
spines longer than in the type, the remaining ones
normal.

Length 32 pi; breadth 30 '5 fi ; breadth of isthmus
97 (JL.

IRELAND. SHeve Donard, Co. Down (abundant
amongst Sphagnum) \

100. Staura strum scabrum Breb.
(PL CXL, figs. 1, 2.)

St. scabrum Breb in Ralfs, Brit, Desm. 1848, p. 214, t. 35, f. 20 ; Arch, in
Pritch. Infus. 1801, p. 740; Rabenh. Flor. Europ. Alg. 1868, p. 217;
Lund. Desm. Suec. 1871, p. 65 ; Wolle, Desm. U. S. 1884, p. 130, t. 41,
f. 29, 30 ; Boldt, Desm. Gronland, 1888, p. 39, t. 2, f. 50 ; De Toni,
Syll. Alg. 1889, p. 1170; West, Alg. X. Wales, 1890, p. 18; Ltitkem.
Desm. Attersees, 1893, p. 564 ; Roy & Biss. Scott. Desm. 1893, p. 25 ;
Borg. in Wittr. & Nordst. Alg. exs. no. 1114, 1893, p. 11; Schmidle,
Beitr. Alp. Alir. 1896. p. 32 ; Comere, Desm. de France, 1901, p. 170,
t. 13, f. 6 ; West & G. 8. West, Alg. N. Ireland, 1902, p. 51, t. 2, f. 36 ;
Brit. Freshw. Phytoplankton, 1909, p. 203.

Cells small, a little longer than broad, deeply con-
stricted, sinus open and acute ; semicells elliptic-
fusiform or subtrapeziform, dorsal margin mor econvex
than the ventral, peripheral margin granulate, lateral
angles subtruncate with about 3 acute granules at each ;
cell- wall granulate, granules arranged in 8 longitudinal
rows down the face of the semicell, those near the angles
consisting of simple granules, but in the 4 median series
the granules scattered in groups. Vertical view trian-
gular, angles rounded, sides very slightly concave, mar-
gins denticulate, granules in the median part of the
lateral margins often emarginate, and with about 2 series
of emarginate granules just within the margin. ^ Chloro-
plast axile, with a central pyrenoid in each semicell and
a pair of lobes extending into each angle.

Zygospore globular, sometimes slightly oblong, with
short stout spines 3- or 4-fid at the apex, about 10-13
visible round the margin (Roy & Biss.).

Length 35-36 u. ; breadth 32-38 (i ; breadth of isth-

t> - r- a

VOL. V.

82 BRITISH DESMIDIACE.E.

mus 9-1 3 '5 p. ; diam. zygosp., without spines, 32-35 pt ;
length of spines 5-6 p.

ENGLAND.- -Lunds Fell, N. Yorks !

WALES. — Capel Curig, Moel Siabod, Llyn Bochlwyd
and Llyn-y-cwm-frynon, Carnarvonshire !

SCOTLAND.- -Shetlands, Sutherland, Ross, Moray,
Aberdeen, Kincardine, Forfar, Perth, Fife, Argyle, Arran ;
zygospores from Cambus O'May, Aberdeen (Roy&Biss.}.
Orkneys !

IRELAND. — Glendowan, near Glenties, and Loughs
Anure, Clogher and Magrath, Donegal ! Achill Isle,
Mayo ! Dublin and Wicklow (Arch.}.

Geogr. Distribution.- -France. Germany. Switzerland.
Austria. Norway. Sweden. Denmark. Finland. Faeroes.
Greenland. Azores. United States.

101. Staurastrum subscabrum Nordst.
(PL CXL, figs. 3, 4.)

St. subscabrum Nordst. Alg. aq. dulc. et Char. Sandvic. 1878, p. 16, t. 2,
f. 1 ; De Toni, Syll. Alg. 1889, p. 1177 ; West & G. S. West, Some N.
Amer. Desm. 1896, p. 260, t. 18, f. 12 ; Comere, Desm. de France, 1901,
p. 172, t. 12, f. 21 ; West & G. S. West, Alg. X. Ireland, 1902, p. 51,
Brit. Freshw. Phytoplaiikton, 1909, p. 203.

Cells small, about as long as broad, nearly circular
in outline, deeply constricted, sinus narrow, some-
times even linear ; semicells subpyramidate- truncate,
broad at the base, apex subtruncate, lateral margins
slightly convex, about 6-8 granules visible along each,
the upper ones emarginate ; cell- wall provided with
verrucse arranged in decussating horizontal and longi-
tudinal rows, the median ones emarginate ; horizontal
series 4 in number, vertical series about 6 or 8. Vertical
view triangular, sides straight, each with about 4 or 6
emarginate verrucee, and another similar series just
within the margin, angles obtuse, with a few granules,
centre of apex smooth. Chloroplast axile with a central
pyrenoid in each semicell.

Zygospore unknown.

STAURASTRUM. 83

Length 27-32 pi ; breadth 26-32 [i ; breadth of isth-
mus 7'5-14fji.

ENGLAND.- -New Forest, Hants !

SCOTLAND. — Glen Dye, Kincardine (Roy & Biss.).
Rhiconich, Sutherland !

IRELAND.- -Lough Nacung, Donegal ! Kylemore, Gal-
way !

Geogr. Distribution.- -France. Sandwich Isles. United
States.

St. subscabrum differs from St. scabnun in its proportionately
shorter cells ; the sinus is narrower, and the semicells are more
truncate-pyramidate in outline.

Forma scabrior West. (PL CXL, fig. 5.)

St. subscabrum forma scabrior West, Alg. W. Ireland, 1892, p. 176, t. 23,
f. 4.

Differs from the type in its greater development of
verrucaa, especially at the apices of the cell.

Length 40 \L ; breadth 35-37 \L ; breadth of isthmus

10 p.

IRELAND.- -Kylemore and Clifden, Co. Galway !

SECTION H.

Processes smooth, although usually emarginate, furcate or spinate
at the extremity.

* Processes borne singly at the angles of the semicell.

f Processes always entire and distinctly capitate at the

extremity.

102. St. bacillare.

ft Processes truncate, obtuse or furcate at the extremity,

never capitate.
± Cells minute, semicells rectangular in form.

103. St. franconicum.

104. St. inconspicuum.

105. St. nodosum.

It Cells larger, semicells cuneate.

106. St. bmchiatum.

107. St. Icevispinum.

108. St. sublcevispimim.

84 BRITISH DESMIDIACE^.

t}J Semicells globular.

109. St. subnudibrachiatum*
** Processes in pairs at the angles, all in the same horizontal

plane.

110. St. Iceve.

102. Staurastrum bacillare Breb.
(PI. CXLI, figs. 9, 10.)

Binatella bacillaris Breb. Alg. Falaise, 1835, p. 269.

Staurastrum bacillare Breb. in Menegh. Synops. Desm. 1840, p. 228 ; RaKs.,

Brit. Desm. 1848, p. 214, t. 35, f. 21 ; Breb. Liste Desm. 1856, p. 145 ;

Arch, in Pritch. Inf. 1861, p. 741 ; Rabenh. Flor. Europ. Alg. 1868, p. 201 ;

Wolle, Freshw. Alg. U. S. 1887, p. 41, t, 57, f. 5, 6 ; De Toni, Syll. Alg.

1889, p. 1186 ; West, Alg. W. Ireland, 1892, p. 173 ; Comere, Desm. de

France, 1901. p. 173, t. 12, f. 29 ; West & G. S. West, Brit. Freshw.

Phytoplankton, 1909, p. 202.

Phycastrum bacillare Kiitz. Spec. Alg. 1849, p. 181.
Didymidium (Staurastrum) bacillare Reinsch, Alg. Frank. 1867, p. 153.

Cells small, deeply constricted, sinus acute and nearly
rectangular ; semicells narrowly lunate, angles produced
obliquely upwards into thick processes, ending with
capitate apices. End view 3-5-angular, sides strongly
concave, angles produced with capitate apices. Cell-
wall smooth.

Zygospore unknown.

Length, without processes, about 16'2(ji ; with pro-
cesses, 33 '8 ^; breadth, with processes, 30-37 '5^;
breadth of isthmus 7-87 p.

IRELAND.- -Lough Aunierin, Co. Gal way ! Minister
and Connaught (Adams).

Geogr. Distribution.- -France. Germany. Poland.
Burma. United States. West Indies.

Var. obesum Lund. (PL CXLI, figs. 11, 12.)

St. bacillare var. obesum Lund. Desm. Suec. p. 57, t. 3, f. 24 ; De Toni, Syll.
Alg. 1889, p. 1187 ; West, Alg. N. Wales, 1890, p. 16, t. 5, f. 4 ; Alg. W.
Ireland, 1892, p. 173 ; Eichler, Mat. nor. Miedz. 1894, p. 133, t. 4, f. 55.

A variety with proportionately larger body of semi-
cell ; processes horizontal and very much reduced,
almost entirely wanting, apex of cell slightly convex.

STAURASTRUM. 85

Length 17-5-23 p ; breadth 21-27 fi ; breadth of isth-
mus 6-7'5fjL.

WALES. — Capel Curig, Carnarvonshire !
SCOTLAND.— Loch Dawan, Aberdeen (Roy & Biss.).
IRELAND. — Adrigole, Co. Cork !
Geogr. Distribution. — Sweden. Finland. United States.

Var. undulatum var. nov. (PI. CXLI, fig. 13.)

X/. h'icillarc var. 11 ml itlntii.ni \\ . & (',. S. \Vestin manuscript.

Cells rather larger and relatively longer than in the
type, processes long and slender, more divergent, and
with their outlines gently undulate. Vertical view
triangular with very concave sides.

Length, without processes, 18 \i ; with processes, 44 \L ;
breadth 37 \L ; breadth of isthmus 8'5 [/..

SCOTLAND.- -Rhiconich, Sutherland !

St. bacillare is a very rare Desmid, and only occurs in bogs
on the older paleozoic rocks in the western parts of the
British Isles. It is very variable in form, and scarcely any of
the figures yet published agree exactly with the figures of Ralfs.
Lagerheim (' La nuova Xotarisia,' 1892, p. 29) would make definite
varieties of the forms figured by both West (< Alg. X. Wales,' 1890,
t. 5, f. 4) and Wolle (' Fresh w." Alg. U.S.' 1887, t, 57, f. 5-6).

103. Staurastrum franconicum Keinsch.
(PI. CXLII, figs. 9, 10.)

St. franconicum Reinsch in Rabenhorst, Alg. Eur. no. 1899, f. 1-3, 1860;
Spec. Gen. Alg. 1867, p. 124, t. 4, B ; Lund. Desm. Suec. 1871, p. 5i
De Toni, Syll. Alg. 1889, p. 1213 ; Roy & Biss. Scott, Desm. 1893, p. 182.

Didymidium (Staurastrum) franconicum Reinsch, Algenfl. Frank,
p. 158, t. 12, f. 3.

Cells small, about as long as broad, excluding the
processes, or a little longer ; body of cell nearly rect-
angular in form ; sinus almost wanting, consisting of a
minute excavation in the middle ; semicells short and
rectangular, apex and lateral margins concave or nearly
straight, upper angles of semicell produced to form short

86 BRITISH DESMIDIACE^E.

divergent processes, which are emarginate or tri-dentate
at the apex ; vertical view 2-5 -radiate, lateral margins
strongly concave, angles produced into processes. Cell-
wall smooth, except for the processes, which are some-
times finely granulate.

Zygospore unknown.

Length (not including the processes) 14-17 [/. ; breadth
(not including the processes) ll-15(i; distance between
the tips of the processes 19-30 y..

SCOTLAND.- -Bishop's Loch and Tomachar, Aberdeen
(Roy & Biss.).

Geogr. Distribution. — Germany. Italy. Scandinavia.
United States.

Reinsch's figures include several Staurastra which differ
amongst themselves in many respects, so that one almost doubts
that they can all belong to the same species. Unfortunately,
no other figures of St. franconicum have ever been published,
and these original ones of Reinsch are very unsatisfactory.

104. Staurastrum inconspicuum Nordst.
(PL CXLI, figs. 4-7 ; PL CXLII, fig. 8.)

Staurastnim sp. Arch, in Quart. Journ. Micr. Sci. 1855, p. 89.

St. minutissimum Auersw. in Rab. Alg. Eur. 1863, no. 1428 (ex parte).

St. inconspicuum Nordst. Norges Desm. 1873, p. 26, t. 1, f. 11 ; Arch, in
Journ. Bot. 1874, p. 91 ; Wolle, Desm. U. S. 1884, p. 125, t, 53, f. 4, 5 ;
Cooke, Brit, Desm. 1887, p. 153, t. 54, f . 3 ; De Toni, Syll. Alg. 1889,
p. 1183; Heimerl, Desm. alp. 1891, p. 606; West, Alg. W. Ireland,
1892, p. 178; Liitkem. Desm. Attersees, 1893, p. 565; Roy & Biss.
Scott, Desm. 1893, p. 21 ; West & G. S. West, Some N. Amer. Desm.
1896, p. 257. t, 16, f. 14 ; Alg. S. England, 1897, p. 495 ; Liitkem. Desm.
Millstattersees, 1900, p. 22, t. 1, f. 54 ; Comere, Desm. de France, 1901,
p. 154, t. 11, f. 11 ; Borg. Alg. Faeroes, 1901, p. 235, t. 8, f. 4 ; West &
G. S. West, Alg. N. Ireland, 1902, p. 49 ; Brit. Freshw. Phytoplankton,
1909, p. 203.

St. refractum Delp. Spec. Desm. subalp. 1877, p. 138, t. 11, f. 7-9.

St. subrefractum Lemaire, Liste Desm. Vosges, 1883, p. 23, t. 1, f. 3.

Cells minute, about as long as broad, including the
processes, sinus nearly semicircular ; semicells roughly
quadrangular, apex slightly elevated but concave in
the middle; upper angles produced to form short stout

STAURASTRUM. 87

processes, which are first directed obliquely outwards,
and then, at a point halfway along their length, they
are abruptly narrowed and directed obliquely upwards,
ending with truncate apices. Vertical view 3-6-radiate,
sides strongly concave, processes equal in length to about
half the diameter of the ' : body : ' of the cell.

Zygospore oval or elliptical, smooth.

Length, without processes, 14-15*5 ^ ; with processes,
17-26(ji; breadth with processes — length with pro-
cesses ; breadth of isthmus 7-9 [i ; length zygosp. 16 JJL :
breadth ITSpt.

ENGLAND.- -Thursley Common and Devil's Jumps,
Surrey ! New Forest, Hants ! Dartmoor and Woodbury
Common, Devon (Harris) ! Roughter Moor, Cornwall
(Marquand) !

WALES. — Capel Curig, Carnarvonshire !

SCOTLAND. — Sutherland !, Ross, Inverness, Moray,
Aberdeen, Kincardine, Forfar, Perth ! and Argyle (Boy
& Biss.).

IRELAND. — Donegal ! Mayo and Clare Isle ! Galway !
Kerry ! Dublin and Wicklow (Arch.).

Geocjr. Distribution. — France. Belgium. Germany.
Galicia and Austria. Norway. Sweden. Finland.
Poland. N. Russia. Faeroes. " Siam. Azores. United
States. Colombia. Brazil.

Borgeson has observed examples of this species in which the
cells were united to form short twisting filaments (see PL CXLII,
f. 8).

Var. crassum Gay. (PL CXLI, fig. 8.)

St. inconspicuum var. crassum Gay, Mono.loc. Conj. 1884, p. 68, t. 2, f. 1
De Toni, Syll. Alg. 1889, p. 1183 ; West & G. S. West, New Brit. Alg.
1894, p. 11 ; Comere, Desm. de France, 1901, p. 154.

Processes stouter than in the type, distinctly jointed.
Length and breadth, including processes, 12-14 fj. ;
breadth of isthmus 6*5-7 JJL.

IRELAND.— Glen Caragh, Co. Kerry !
Geogr. Distribution- -France.

88 BRITISH DESMIDIACEJE.

Dr. Lutkemliller (' Zellmembr. Desm.' 1902) states that the
chloroplast in St. inconspicuum is very simple and possesses only
one pyrenoid in the middle of the cell (instead of one in each
semicell as is often the case in Staurastrum), so that the nucleus
is lateral in position. This is a very unusual state of affairs for
one of the higher Desrnids. On the other hand, Gay (loc. cit.)
figures for St. inconspicuum var. crassum pyrenoids in quite the
normal position.

105. Staurastrum nodosum W. & G. S. West.

(PL CXLI, fig. 16.)

St. nodosum West & G. S. West, Alg. S. England, 1897, p. 495, t. 6, f. 23.

Cells very small, about as long as broad, including the
processes, deeply constricted, sinus open with almost
straight margins and very acute apex ; semicell s
broadly oblong-rectangular, upper angles produced to
form short truncate processes, strongly divergent, and
with one abrupt constriction, lower angles nearly
rectangular, apex of semicell concave ; vertical view
triangular, sides concave, processes truncate and
biundulate ; cell- wall smooth.

Zygospore unknown.

Length, without processes, 11 11 ; with processes, 21 [JL ;
breadth, with processes, 19[ji ; breadth of isthmus 5jx.

ENGLAND. — Thursley Common, Surrey !

«/ *-

St. nodosum is similar in general appearance to St. incon-
spicuum Nordst., but is distinguished by its marked and deep
constriction, and by the relatively smaller 'body' in the end
view.

106. Staurastrum brachiatum Ralfs.
(PI. CXLI, figs. 14, 15 ; PI. CXLII, figs. 1-7.)

Staurastrum bifidum Ralfs in Ann. Mag. Nat. Hist. 1845, p. 151, t. 10, f. 3.
Goniocystis (Staurastrum} bifida Hass. British Freshw. Alg. 1845, p. 355,

t. 85, f. 2.
Staurastrum bracltiatum Ralfs, Brit. Desm. 1845, p. 131, t. 23, f. 9 ; Arch.

in Pritch. Inf. 1861, p. 741 ; Rabenh. Krypt. Flor. Sachs. 1863, p. 192 ;

De Not. Desm. Ital. 1867, p. 54, t. 5, f. 50 ; Rabenh. Flor. Europ. Alg.

1868, p. 205; Wolle, Desm. U. S. 1884, p. 124, t. 40, f. 37-39; Cooke,

STAURASTKUM. 89

Brit. Desm. 1887, p. 167, t, 58, f. 1 ; De Toni, Syll. Alg. 1889, p. 1202 ;
Anders. Sverig. Chlor. 1890, p. 11 ; West & G. 8. West, New and Int.
Freshw. Alg. 1896, p. 159, t. 4, f. 53-56 ; Some X. Amer. Desm. 1896,
p. 262, t. 16,. f. 32 ; Alg. S. England, 1897, p. 494 ; G. 8. West, Variation
Desm. 1899, p. 391, t. 11, f. 5-15 ; West & G. 8. West, Alg. X. Ireland,
1902, p. 49 ; Alga-fl. Yorks. 1902, p. 103 ; Him, Desm. Finnland, 1903,
p. 20 ; G. 8. West, Brit. Freshw. Alg. 1904, p. 172, f. 65, F.

Phycastrum Ralfsii Kiitz. Spec. Alg. 1849, p. 181.

PJi. brachiiitum Perty, Kleinst. Lebensf. 1852, p. 210, t. 10, f. 33.

Cells small, about as long (including processes) as
broad, deeply constricted, sinus acute and rectangular,
minutely excavated at the apex ; semicells somewhat
triangular, apex and sides nearly straight, angles pro-
duced to form stout divergent processes of variable
length, which are 2-3-fid at the apex. Vertical view
3-5-angular, sides strongly concave, sometimes with a
very slight median inflation ; processes hollow to the
extreme tip.

Zygospore irregular and variable in outline, some-
times quadrangular, with a few blunt processes.

Length 27-36'o^; breadth 25-48 fi; breadth of
isthmus 5-9 \L ; diam. zygosp., without processes,
21-30 u.

ENGLAND.- -Westmoreland, and in the plankton of
Easedale Tarn! W., N., and E. Yorks! Gloucester
(Ealfs). Surrey (zygospores from Thursley Common) !
Devon (Hurris) ! Cornwall (Ealfs).

WALES.— Capel Curig (Cooke & Wills) !. Moel Siabod,
Llyn Idwal, near Conway, and Llyn Teyrn. Snowdon,
Carnarvonshire ! Dolgelly, Merioneth (Ealfs).

SCOTLAND.- -Eoss !, Inverness!, Aberdeen, Kincar-
dine, Forfar. Perth !, Argyle, Arran ; zygospores from
Curran and Clochnaben, Kincardine (Roy & Biss.).
Sutherland ! Somewhat rare in the plankton ! Lewis,
Outer Hebrides, and in the plankton ! Shetlands, and
in the plankton of the Orkneys and Shetlands !

IRELAND. — Mayo ! Donegal ! Galway, and in the
plankton ! Kerry, and in the plankton ! Dublin and
Wicklow (Arch.). Down !

Geogr. Distribution.— France. Belgium. Germany.
Switzerland. Galicia in Austria. Hungary. Italy.

90 BRITISH DESMIDIACE^E.

Norway. Sweden. Denmark. Finland. Faeroes.

t>

W. Greenland. Japan. Australia. Azores. United
States. Guiana (var.). Colombia.

St. brachiatum is a frequent inhabitant of Sphagnum bogs,
and is sometimes obtained in abundance from such localities.
It is often found in plankton, but never occurs in great numbers
in this habitat. It is one of the most variable of Desmids,
particularly with regard to the relative length and stoutness of
the processes and the character of their apices. The processes
may be fairly long and slender, or sometimes quite short and
stout, whilst their apices may be 2- or 3-fid, both types occurring
occasionally in the same individual ; or the ultimate divisions
may be bluntly rounded, and in extreme cases wanting alto-
gether. The semicells are frequently twisted so that corre-
sponding angles do not overlie each other.

107. Staurastrum laevispinum Bissett.
(PL CXLI, figs. 17, 18.)

»SV. loecispinum Biss. Desm. Winder-mere, 1884, p. 195, t. 5, f. 5 ; Cooke,
Brit, Desm. 1887, p. 143, t. 50, f . 3 ; De Toni, Syll. Alg. 1889, p. 1144 ;
Roy & Biss. Scott, Desm. 1893, p. 22 ; West & G. S. West, Alg. N
Ireland, 1902, p. 49, t. 2, f. 37 ; Brit. Freshw. Phytoplankton, 1909, p. 202.

Cells small, sinus obtuse and nearly rectangular, with
a minute excavation at its apex ; semicells somewhat
lunate, angles produced into thick, slightly divergent
processes, which are slightly attenuated towards their
obtuse apices ; apex of semicell concave. Vertical view
triangular, sides concave, angles produced and tapering.

Zygospore unknown.

Length 25-30 p ; breadtli 32-39 p ; breadth of isth-
mus 9 [L .

ENGLAND.- -Xear Bowness, Westmoreland (Biss.).
Dartmoor, Devon (Harris).

SCOTLAND.— Goat Fell, Arran (Roy & Biss.). Plank-
ton of Loch nan Eun, N. Uist, Outer Hebrides !

IRELAND.- -E. of Glenties ; Lough Anna and Sproules
Lough, Donegal (form) !

Geogr. Distribution. — Australia (form).

STAURASTRUM. 91

The specimens figured on PL CXLI, f. 18, from Ireland are
not exactly typical, being more or less intermediate in form
between St. Icevispinum and the next described species, St. sub-
lcevispinum. The processes are less attenuated and not so
divergent as in typical St. Icevispinum and the " body " of the
cell is not quite as large. They have more in common with
St. Icevispinum, however, than with St. sublcevispinum.

108. Staurastrum sublsevispinum W. & G. S. West.

(PL CXLI, fig. 19.)

St.subhedspinutii West & G. S. West, Desm. U. S. 1898, p. 314, t. 18, f. 20-22;
Alg. Ceylon, 1902, p. 179; Further Corrtrib. Plankt. Scott, Lochs, 1905,
p. 502, t. 7, f. 23.

Cells small, 1| times broader than long (including the
processes), deeply constricted, sinus open and obtuse ;
semicells with a very small : body," angles produced
into finger-like strongly diverging processes, with parallel
sides and conical apices ; apex of semicell concave.
Vertical view triangular, body : small, and processes
stout. Cell- wall smooth.

Zygospore unknown.

Length 25-33 ^ ; breadth 37-46 JJL ; breadth of isth-
mus 7-8'o [JL.

SCOTLAND.- -Plankton of Loch Fadaghoda, Lewis,
Outer Hebrides !

Geogr. Distribution. — Ceylon. United States.

St. sublcevispinum is closely related to St. Icevispinum, from
which it is distinguished by its relatively greater breadth, and
smaller " body of the semicell ; its processes are cylindrical
and only abruptly attenuated at the apex.

109. Staurastrum subnudibrachiatum W. & G. S.

West.

(PL CXLI, fig. 20.)

St. subnuii;bi',<<-hi,-ttni,i West & G. S. West, Further Contrib. Freshw. Phyto-
plankton Scott, Lochs, 1905, p. 502, t. 7, f. 18, 19.

Cells of medium size, about H times broader than
long, including the processes, body of cell slightly con-

92 BRITISH DESMIDIACE.E.

stricted, sinus very widely open, semicells subspherical ;
lateral margins produced into long, straight, and smooth
processes, which diverge from those of the other semicell ;
apex of processes usually forked into two obtuse teeth,
but sometimes entire and obtuse. Vertical view 4-5-
radiate, processes as long as the ' body : ' of the semicell ;
cell-wall smooth ; processes of one semicell alternating
with those of the other. Chloroplast axile with a large
central pyrenoid.

Zygospore unknown.

Length, without processes, 31-37 \L ; with processes,
40-44 [ji ; breadth, without processes, about 20-22 y. ;
with processes, 53-61 pt ; breadth of isthmus 15-1 5 '5 u.

SCOTLAND.- -Plankton of Loch Fadaghoda, Lewis,
Outer Hebrides !

St. subnudibmchiatum is very similar to St. brachiatum Rails
in the nature of its processes, but it differs widely from that
species in the form of its semicells, and its slight constriction.
The processes are variable in character, even in the same speci-
men. They are usually bifurcate at the extremity, each lobe
being rounded, but sometimes they are obtuse and entire.

It also has some superficial resemblances to St. Clevei (Wittr.)
Boy & Biss., from which it is readily distinguished by its broader
isthmus, by the rounded apical teeth of the processes, and by
the fact that the latter lie all in the same plane.

110. Staurastrum laeve Ralfs.
(PL CXLI, figs. 1-3.)

tit.lceve Ralfs, Brit. Desm. 1848, p. 131, t. 23, f. 10 ; Arch, in Pritch. Infus.
1861, p. 743 ; Rabenh. Krypt. Flor. Sachs. 1863, p. 193 ; Flor. Europ.
Alg. 1868, p. 206 ; Wittr. Gotl. Ol. sotv. Alg. 1872, p. 54 ; Kirchn. Alg.
Schles. 1878, p. 167 ; Cooke, Brit, Desm. 1887, p. 180, t. 63, f. 2 ; Hansg.
Prodr. Algenfl. Bohm. 1888, p. 212 ; De Toni, Syll. Alg. 1889, p. 1227 ;
Roy & Biss. Scott. Desm. 1893, p. 22 ; West & G. S. West, Alg. S. England,
1897, p. 494 ; Comere, Desm. de France, 1901, p. 152, t. 11, f. 14 ; West
& G. S. West, Alga-fl. Yorks. 1902, p. 104 ; Gutw. Alg. Ins. Java, 1902,
p. 606.

Cells very small, about 1| times longer than broad,
not including the processes, deeply constricted, sinus

STAUPxASTRUM. 93

acute and rectangular, minutely excavated at its apex ;
semicells elliptical or subsemicircular, dorsal margin only
slightly convex, ventral margin very tumid ; each angle
of the semicell with a pair of short smooth processes, all
lying in the same horizontal plane, very slightly diver-
gent ; apices of processes bifid, with the two teeth
vertically one above the other. Vertical view 3-5-
angular, sides strongly concave, angles deeply lobed,
each lobe tapering into a short process. Cell-wall
smooth. Chloroplast axile, with a central pyrenoid in
each semicell.

Zygospore spherical, with a number of slender pro-
cesses which are twice dichotomous at the apex.

Length, with processes, 22-27 'O\L ; breadth 23-28 [i ;
breadth of isthmus 7-8 [JL ; diam. zygosp., without pro-
cesses, 18 (JL ; with processes, 30-35 \i.

ENGLAND.- -Xear Bowness, Westmoreland (Bissett).
Strensall Common (W. B. Turner) and Pilmoor, N.
Yorks (very abundant and with zygospores) ! Thursley
Common, Surrey (very abundant) ! Dartmoor (Harris).
WALES.— Cape! Curig, Carnarvonshire (Cooke & Wills).
Outlet of Llyn Gwernan, Dolgelly, Merioneth (Rolfs).

SCOTLAND". — Loch Inver, Sutherland ; Birsemore Loch,
near Loch Dawan and Tomacher, Aberdeen; near
Durris Bridge, Kincardine (Roy & Biss.).

IRELAND.— Achill Isle, Mayo ! Adrigole, Co. Cork ! _
Geogr. Distribution.— France. Germany. Galicia in
Austria. Norway. Sweden. Denmark. Bornholm. Java.
Australia. United States. Brazil.

SECTION I.

Processes rough, denticulate or spinate along their whole length
* Cells without prominent accessory spines on

cell which, at the most, is rough with tiny granule
more acute denticulations, never bearing spine;
great length.

94 BRITISH DESMIDIACEJ3.

f Cells with one process only at each angle of the cell.

Cells not more than four times as long as broad,

excluding the processes.
§ Cells in vertical view 2-5-radiate ; if more than

4-radiate, processes relatively short.
a. Faces of semicell smooth or provided with
granules or small dentieulations ; con-
spicuous verruca? never present except
on the apex of the semicell.
A. Processes well developed, at least as
long as the body of the cell is
broad, and frequently longer ;
semicells usually distinctly cuneate
or cup-shaped, bearing the pro-
cesses at the upper angles of
the cells.

1. Cells fairly large, more than
20 /x long excluding the pro-
cesses.

111. St. gracile.

112. St. paradoxum.

113. St. pseudopelagicum.

114. St. inflexum.

115. St. crenulatum.

116. St. neglectum.

117. St. dubium.

118. St. boreale.

119. St. Pseudosebaldi.

120. St. Manfeldtii.

121. St. Diiacense.

122. St. bicorne.

2. Cells small, less than 20 /x long,
excluding the processes.

123. St. subgradllinmm.

124. St. tetracerum.

125. St. iotanum.

126. St. pseudotefracerum.

127. St. micron.

128. St. latiusculum.

B. Processes only feebly developed, not
as long as the body of the cell is
broad.

1. Processes solid, deeply bifid at

their apices.

129. St. pelagicum.

2. Processes hollow for their whole

length.

STAURASTEUM. 95

I. Dorsal margin of the semi-
cell less convex than the
ventral ; semicells more
or less cup-shaped.
! Processes straight, aris-
ing from the upper
angles of the cell.

130. St. polymorphum.

131. St. ciffine.

132. St. proboscidium.
115. St. crenulatum.

133. St. margaritaceum.

134. St. Chavesii.

!! Processes strongly in-
flexed.

135. St. cyrtocerum.

136. St. bmchycei'iun.

137. St. eboracense.

II. Dorsal and ventral margins
almost equally convex :
semicells subfusiform.

138. St. hexacerum.

139. St. Haaboeliense.

b. Faces of seniicell provided with large and
prominent verrucse, often flattened
and complex, either on a central
protuberance (in the biradiate forms),
or in definite series.

140. St. Cerastes.

141. St. anatinum.

142. St. sexcostatum.

143. St. natatof.

144. St. irregulare.

§§ Cells in vertical view usually 5-9 rayed, pro-
cesses nearly twice as long as the ' body '
of the cell is broad, and radiating like the
spokes of a wheel.

145. St. Arachne.

146. St. Ophiura.

147. St. verticillatum.

148. St. Archeri.

Cells 6 times as long as broad, excluding the
processes.

149. St. elongatum.

tf Cells with 2 processes at each angle, all lying in the same
horizontal plane.

150. St. barbaric utit.

96 BRITISH DESMIDIACE^.

** Cells with prominent accessory spines, either simple or
emarginate, but of considerable length, on the " body '
of the cell.

151. St. vestitum.

152. St. aculeatum.

153. St. controversum .

154. St. cosmospinosum.

155. St. HeimerUanum.

156. St. Sebdldi.

157. St. oxyacanihum.

158. St. dorsidentiferum.

159. St. acicidiferum.

111. Staurastrum gracile Ralfs.
(PI. CXLIV, figs. 3-7.)

Staurastrum gracile Ralfs, in Ann. Mag. Nat. Hist. 1845, p. 155, t. 11, f. 3 ;
Brit. Desm. 1848, p. 136, t. 22, f. 12 ; Arch, in Pritch. Infus. 1861, p. 742,
t. 3, f. 28, 29 ; Rabenh. Krypt. Flor. Sachs. 1863, p. 192 ; De Not.
Desm. Ital. 1867, p. 54, t. 5, f. 49 ; Rabenh. Flor. Europ. Alg. 1868,
p. 211; Arch, in Quart, Journ. Micr. Sci. v. 10, 1870, p. 86; Nordst,
Norges Desm. 1873, p. 74 ; Jacobs. Desm. Danem. 1875, p. 207 ;
Delp. Spec. Desm. subalp. 1877, p. 153, t. 12, f. 12-21 ; Kirchn. Alg.
Schles. 1878, p. 167 ; Wolle, Desm. U. S. 1884, p. 133, t, 43, f. 16, 17 ;
Cooke, Brit. Desm. 1887, p. 170, t. 58, f. 6 ; De Toni, Syll. Alg. 1889,
p. 1209 ; Anderss. Sverig. Chloroph. 1890, p. 12 ; West, Alg. W. Ireland,
1892, p. 181 ; Roy & Biss. Scott. Desm. 1893, p. 20 ; West & G. S. West,
Alg. S. England, 1897, p. 495, t. 6, f. 27 ; Desm. U. S. 1898, p. 317, t. 18,
f. 7 ; Ale. X. Ireland, 1902, p. 54 ; Alga-fl. Yorks. 1902, p. 105 ; Ale.
Ceylon, 1902, p. 190 ; Scott, Freshw. Plankt. I, 1903, p. 549, t. 18, f. id";
Freshw. Ale;. Orkneys & Shetlands, 1905, p. 27 ; Teodoresco, Mater, flor.
Alg. Roumania, 1907, p. 186 ; Kofoid, Plankt. Illinois, 1908, p. 61 ;
Gutw. Flor. Alg. Mont. Tatr. 1909, p. 475 ; Wahlburg, Bidr. kanne.
Littois-trask, 1913, p. 47, t. 1, f. 7.

Phycastnun gracile Kiitz. Spec. Alg. 1849, p. 181.

Diclyntidiion (Staurastrum) gracile Reinsch, Algenfl. Frank. 1867, p. 166.

Cells variable, usually of small or medium size, 2-2^
times longer than broad, excluding the processes; con-
striction slight, usually an acute notch ; semicells
variable in form, usually more or less cup-shaped,
lower angles broadly rounded, lateral margins nearly
vertical or slightly diverging, rarely slightly concave,
semicells usually broadening slightly towards the apex,
which is very slightly convex ; upper angles produced
to form long slender processes of variable length, each
tipped with 3 or 4 minute spines, and provided with
several concentric series of denticulations ; processes

STAURASTRUM. 97

usually horizontal, sometimes slightly converging. Ver-
tical view usually triangular, sometimes quadrangular ;
sides straight or rarely slightly concave, angles produced
to form long processes, lateral margins often with a
series of minute granulations, sometimes paired, just
within the margin. Chloroplast axile, with a central
pyrenoid in each semicell.

Zygospore spherical, provided with numerous spines,
broad at the base, and once or twice divided at the
apex.

Length 27-60 y. ; breadth, including processes, 44-
110 IJL ; breadth of isthmus o'o-lSpi; diam. zygosp.,
without processes, 32 jx ; with processes, 60 (JL.

ENGLAND. — Cumberland, and in the plankton of
Buttermere ! Westmoreland ! Lancashire ! (Rolfs). W.,
N., and E. Yorks., and in the plankton of Gormire, N.
Yorks ! Leicestershire (Roy). Essex ! Burnham Beeches,
Bucks ! Oxford ! Surrey (zygospores from Thursley
Common) ! Hants ! (Roy). Devon ! (Harris). Cornwall !

WALES. — Fairly general (at 2200 feet on Glyder
Each) ! In the plankton !

SCOTLAND. — Sutherland !, Koss !, Inverness !, Aber-
deen, Kincardine, Forfar, Perth !, Argyle and Fife (Roy
& Biss.). Cumbrae, Ayr ! Near Lochmaddy, N. Uist,
and in Lewis and Harris, Outer Hebrides ! Orkneys and
Shetlands, also in the plankton ! More or less general
in the plankton !

IRELAND. --Donegal ! Mayo and Clare Isle, and in the
plankton of Mayo ! Galway and in the plankton !
Kerry and in the plankton ! Dublin and Wicklow
(Arch.). Plankton of Lough Neagh ! Londonderry !

Geogr. Distribution.- -Fiance. Germany. Switzerland.
Galicia and Austria. Hungary. Roumania. Italy.
Norway. Finmark. Sweden. Denmark. Bornholm.
Finland. Poland. N. Eussia. Caucasus. Greenland.
Siberia. Mongolia. Central China (var.). Japan. Turkey
in Asia. Ceylon. Australia. Madagascar (var.). E.,
Central, and S. Africa. United States. Canada. Brazil.
Paraguay.

VOL. v. 7

98 BRITISH DESMIDIACE^.

St. gracile is one of the most widely distributed and, at the
same time, most variable of Desmids, being variable both in the
form of its semicells, and the relative proportions of its " body '
and processes. It is very closely allied to St. paradoxum Meyen,
and it is sometimes very difficult to distinguish between the
two species. The chief difference between them is that the
processes of St. gracile are horizontal or slightly converging in
the front view, whereas in St. paradoxum they are usually
shorter in proportion and divergent. The strength of the granu-
lation is also variable in this species. The granules are usually
stronger on the processes, and, if present on the "body" of the
semicell, they are very minute and little more than punctulations.
The plankton forms are often much larger than usual, and deviate
considerably from the typical form. The specimen figured on
PL CXLIV, fig. 6, is a peculiar plankton form with processes
tapering from a very broad base, and the apical granules so
strongly developed as to be almost spines. PL CXLIV, fig. 3
is a rather puzzling Desmid which was identified by Prof. G. S.
West as St. gracile in spite of its slightly divergent processes.

Var. bicorne Bulnh.

St. gracile var. bicorne Bulnh. in Hedwigia, 1861, p. 51, t. 9, f . 2 ; Arch, in
Quart. Journ. Micr. Sci. 1870, p. 86 ; Jacobs. Desm. Dane. 1875, p. 207 ;
De Toni, Syll. Alg. 1889, p. 1209 ; Roy & Biss. Scott. Desm. 1893, p. 20.

Cells in front view similar to the type ; in end view
broadly fusiform, elongated at the poles to form pro-
cesses.

Length 31 '3-32*5 p ; breadth, including processes,
52 '5-57 '5 ; thickness 15 (JL ; breadth of isthmus 12*5 pi.

SCOTLAND.- -Upper Powlair, Slewdrum, Birsemore
Loch, Craigendinnie, Heughhead, west of the Ord, near
Loch Dawan, Homehead, Birkhill and Mosston Moor$
Aberdeen ; Scolty Dam and Dalbrake, Kincardine ;
Fowlis Wester, Perth (Roy & Biss.).

IRELAND. — Mullingar, Co. Westmeath (Archer).

Geogr. Distribution. — Germany. Norway. Sweden.
Denmark. Finland.

Var. bulbosum West. (PL CXLIV, fig. 13.)

St. gracile subsp. bulbosum West, Alg. W. Ireland, 1892, p. 182, t. 23, f.ll.
St. gracile var. bulbosum West & G. S. West, Alg. N. Ireland, 1902, p. 54.

STAUKASTKUM. 99

Semicells, excluding the processes, relatively a little
longer than in the type, slender and campanulate,
gracefully inflated at the base ; sinus deeper than usual,
and almost linear ; processes long and slender, bifid at
the apex ; in vertical view triangular, with a series of
small granules within the lateral margins.

Length 52 [i ; breadth, including processes, 95 ji ;
breadth at base of semicell 18[i ; breadth of isthmus

11 [L.

IRELAND.- -Lough Darragh, Donegal ! Derryclare
Lough, Gal way !

The chief distinction between var. bulbosum and the typical
form seems to be the gracefully swollen base of the semi-
cell. Intermediate stages, however, do occur. For example
the peculiar specimen figured on PL CXLIV, fig. 6 from the
plankton of Loch Doon shows a tendency to cylindrical form
of the body of the semicell with slightly inflated base.

Var. cyathiforme W. & G. S. West. (PL CXLIV,

fig. 12.)

St. gracile var. cyathiforme West & G. S. West, Freshw. Alg. Madag. 1895,
p. 77, t. 9, f. 2 ; Wehv. Afric. Alg. 1897, p. 182 ; Furth. Contrib. Plankton
.Scott, Lochs, 1905, p. 504.

Semicells cyathiform, slightly swollen at the base,
lateral margins undulate and denticulate, apex of semi-
cell convex, with a row of emarginate verrucse continued
as smaller teeth along the dorsal margin of the processes,
which are tipped with a few small spines ; vertical view
with a series of emaminate verrucse within each lateral

o

margin ; cell- wall punctate.

Length 52-58 p ; breadth, including processes, 80-
88 pi ; breadth of isthmus 8-15 p.

SCOTLAND.— Plankton of Lochs an Sgath and Fada-
ghoda, Lewis, Outer Hebrides !

IRELAND. — Plankton of Loch Currane, Kerry !

Geogr. Distribution.— Central China (form). Mada-
gascar. W. Africa.

The British examples of this variety differ from the originaUy

100 BRITISH DESMIDIACE^:.

described specimens from Madagascar in that the sides of the
semicells are simple, without denticulations or undulations, and
the apical teeth of the processes are considerably larger.

Var. coronulatum Boldt. (PL CXLIV, fig. 10.)

St. gracile v&r. coronulatum~B6ldt, Sibir. Chlorophy. 1885, p. 116, t. 5, f. 28 j
De Toni, Syll. Alg. 1889, p. 1209 ; West, Alg. Engl. Lake Distr. 1892,
p. 20, t. 9, f. 36 ; Liitkem. Desm. Attersees, 1893, p. 567.

Cells sometimes rather smaller than in the type, often
more depressed and with slightly shorter processes ;
apex of semicell slightly convex, with two emarginate
processes at the top of each face ; vertical view triangular
or quadrangular, with two emarginate verrucse within
each lateral margin.

Length 21-36 fj. ; breadth, including processes, 32 '5-
43 [j. ; breadth of isthmus 6-11 [i.

ENGLAND. — Bowness, Westmoreland !

Geogr. Distribution. — Germany. Austria. Siberia.

Var. tenuissima Boldt. (PL CXLIV, fig. 11.)

St. gracile var. tenuissima Boldt, Sibir. Chlorophy. 1885, t. 5, f. 29 (without
description) ; Roy & Biss. Scott. Desm. 1893, p. 20.

Cells more depressed than in the type ; semicells
subfusiform, produced at the lateral angles to form
processes longer and more slender than usual. Vertical
view quadrangular, with 3 tiny granules within each

concave margin.

Length 18 [i ; breadth, excluding processes, about 14 p.;
with processes, 40 y. ; breadth of isthmus 6 JJL.

SCOTLAND.- -In Skye and at Brin, Inverness ; Haugh-
ton and in Glen Clunie, Aberdeen ; Crathes and Glen
Dye, Kincardine ; Glen Garry, Perth (Roy & Biss.).

Geogr. Distribution. — Siberia.

Var. nanum Wille. (PL CXLIV, figs. 8, 9.)

St. gracile var. nanum Wille, Norges Ferskv. Alg. 1880, p. 46, t. 2, f. 31 j
Racib. Nonn. Desm. Polon. 1885, p. 33, t. 12, f. 6; De Toni, Syll. Alg.
1889, p. 1209 ; West, Alg. W. Ireland, 1892, p. 182 ; West & G. S. West,

STAURASTRUM. 101

Alg. S. England, 1897, p. 495 ; Alga-fl. Yorks. 1902, p. 105 ; Alg. N.
Ireland, 1902. p. 54 ; Freshw. Alg. Orkneys and Shetlands, 1905, p. 27 ;
Kaiser, Algenfl. Traunstein u. Chiemgau, I, 1914, p. 152.

Cells considerably smaller than in the type, and with
much shorter processes ; apex of semicell nearly straight
or slightly convex ; end view 3-5-angular.

Length 14-27 '5 JJL; breadth, including processes,
23-25 fx ; breadth of isthmus 4-8 '7 \L.

ENGLAND.- -Harrop Tarn, Cumberland ! Plankton of
Brother's Water, Codale and Easedale Tarns, West-
moreland ! Pilmoor, N. Yorks ! Skipwith Common,
E. Yorks ! Near Goring, Oxfordshire ! Near Chapel
Wood and Bisley Common, Surrey ! New Forest. Hants !

WALES. — Capel Curig, Snowdon and Llyn Idwal,
Carnarvon !

SCOTLAND.- -Rhiconich, Sutherland ! Plankton of
Loch Bairness, Inverness !, and of Loch Stranabhat,
Lewis, Outer Hebrides ! Orkneys !

IRELAND.- -Donegal ! Mayo! Galway ! Kerry!

Geoyr. Distribution. — Germany. Galicia in Austria.
Norway. Finland. Poland. Ceylon.

112. Staurastrum paradoxum Meyen.
(PL CXLV, figs. 1-5.)

Staurastrum paradoxum Meyer, Beobacht. niedere Alg. 1828, p. 777, t. 43,
f. 37, 38 ; Menegh. Syn. Desm. 1840, p. 227 ; Ralfs in Ann. Mag. Nat.
Hist, v. 15, 1845, p. 151, t, 10, f. 2 ; Kiitz. Phyc. generalis, 1843, p. 163 ;
Ralfs, Brit. Desm. 1848, p. 138, t, 23, f. 8 ; Arch, in Pritch. Inf. 1861,
p. 742 ; Rabenh. Krypt. Flora Sachs. 1863, p. 191 ; Flor. Europ. Alg.
1868 p 210; Delp/Spec. Desm. subalp. 1877, p. 56, t. 11, f. 63-65;
Kirchn. Alg. Schles. 1878, p. 167 ; Wolle, Desm. U. S. 1884, p. 129, t. 42,
f. 36, 37 ; Cooke, Brit, Desm. 1887, p. 171, t. 59, f. 4 ; Nordst. Freshw.
Alg. N. Zealand, 1888, p. 38, t, 4, f. 10, 11 ; De Toni, Syll. Alg. 1889,
p 1211 ; Turn. Freshw. Alg. E. India, 1893, p. 125, t. 15, f. 4, a, b, d, and
e ; Roy & Biss. Scott. Desm. 1893, p. 23 ; West & G. S. West, Alg. S.
England, 1897, p. 496 ; Comere, Desm. de France, 1901, p. 157, t. II,
f 19 ; West & G. S. West, Alga-fl. Yorks. 1902, p. 106 ; Von Keissler,
Plankt. Hallst. Sees, 1903, p. 338 ; West & G. S. West, Scott Freshw.
Plankton. 1903, p. 548, t. 18, f. 4, 5 ; Freshw. Alg. Orkneys & ; >
1905, p. 27, t, 2, f. 33-35, Ostenf. & Wesenberg-Lund, Fortnightly
Expl. Plankt. Icel. Lakes, 1906, p. 1112, t. 25, f. 14 ; W. & G. S. West,
Brit, Freshw. Phytopl. 1909, p. 175.

Micrasterias Staurastrum Kiitz. Syn. Diat, 1834, p. 71.

Phycastrum paradoxum Kiitz. Phyc. Germ. 1845, p. 138 (in part) ;
Alg. 1849, p. 180 (in part).

Ph. tridens Kiitz. Spec. Alg. 1849, p. 180 (in part).

102 BRITISH DESMIDIACE^}.

Ph. (Stenactinium) paradoxum Nag. Gatt. einz. Alg. 1849, p. 128.
Didymidium (Stauraslrum) paradoxum Reinsch, Alg. Frank. 1867, p. 164
(in part).

Cells of small or medium size, 1 |-2j times longer than
broad, excluding the processes ; constriction moderately
deep, sinus acute ; semicells cup-shaped or cuneate,
lower angles broadly rounded, semicells becoming wider
towards the apex, which is nearly flat, upper angles
produced to form fairly long tapering and diverging
processes, tipped with 3 or 4* spines of varying size, and
provided with numerous series of denticulations. Ver-
tical view usually 3- or 4-angular, sides straight or very
slightly concave, angles produced into ]ong processes,
centre of apex quite smooth, sometimes with a series of
short spines or granules just within each lateral margin.
Chloroplast axile, with a central pyrenoid in the centra
of each semicell and a pair of lobes extending into each
angle.

Zygospore globular, not large, with few long spines,.
2-3-fid at the apex (Roy & Bissett).

Length 21-36 (JL ; breadth, including processes, 41-
70 [Ji ; breadth of isthmus 5-12^.

ENGLAND. — Cumberland, and in the plankton of
Buttermere, Crummock Water, Derwentwater and
Wast Water ! Westmoreland, and in the plankton of Red
Tarn, Grasmere and Windermere ! W., N., and E. Yorkst
Oxfordshire ! Plankton of pools in Sutton Park, War-
wickshire ! Gloucester (Ralfs). Surrey ! Sussex (Rolfs).
Hants ! (Roy). Devon (Harris). Cornwall !

WALES.- -Bethesda !, Capel Curig ! (Cooke & Wills),
Llandudno !, Llyn Bochlwyd !. Bettws-y-coed (Roy),
Llyn-y-cwm-ffynon ! and Glyder Fach !, Carnarvonshire.
Llyn Cor on !, Anglesea, and Holy head !

SCOTLAND. — General, zygospore from Kerloch, Kin-
cardine (Roy & Biss.). Lewis and Harris, Outer Hebrides!
Orkneys and Shetlands, and in the plankton ! Common
in the general plankton !

IRELAND.- -Donegal ! Mayo ! Galway ! Kerry ! Dub-
lin and Wicklow (Arch.). Down ! Plankton of Mayo

STAURASTRUM. 103

and Achill Isle, Galway, Kerry, and Lough Beg, London-
derry !

Geogr. Distribution.— France. Germany. Switzerland.
Galicia and Austria. Hungary. Italy. Norway. Sweden.
Denmark. Bornholm. Finmark. " Poland. "N. and s!
Eussia. Faeroes. Iceland. Greenland. Siberia (var.).
Japan. Turkey-in-Asia. Australia. United States.
Canada. Guiana. Brazil. Patagonia.

The nearest relative of St. paradoxum is St. gracile. From
the latter species it is distinguished chiefly by its diver-
gent processes. Both species are subject to considerable varia-
tion, and transitional forms between the two species are not
infrequent, in consequence of which specimens are occasionally
encountered which cannot with any degree of certainty be
referred either to the one species or to the other. Even amongst
the collections of Professor West are some gatherings labelled
with a query. This proves that the identification of some
forms is impossible.

The divergence of the processes is not usually very great in
the typical form, but some specimens from plankton have pro-
cesses which are more divergent, and very often relatively
longer as well. Other plankton forms bear a superficial
resemblance to St. pseudopelagicum. The strength of the granu-
lation varies, as does also the length of the apical spines of the
processes. Sometimes the granules at the base of the processes
become strengthened into short spines, and in some cases there
is a row of such spines just within each lateral margin in the
end view. The "body" of the semicell is usually quite smooth.

St. paradoxum is quite a common species in this country, and
has a world-wide distribution. The biradiate form has been
recorded from the plankton of Bracebridge Pool, Sutton Park,
Warwicks.

Var. longipes Nordst. (PL CXLVI, figs. 2, 3.)

St. paradoxum var. longipes Nordst. Norges Desm. 1873, p. 35, t. 1, f. 17 ;
Cooke, Brit. Desm. 1887, p. 171, t. 59, f . 4 ; De Toni, Syll. Alg. ]
p. 1212 ; West, Alg. N. Wales, 1890, p. 18 ; Turn. Freshw. Alg.
1893, p. 125, t. 4, f. 4 c and f ; Roy & Biss. Scott. Desm. 1 »3, p. -
Borge,Schwed. Siisswasserplankton, 1900, p. 6, t. 1, f. 4 ; Liitkem. 1
Central China, 1900, p. 124 ; West & G. S. West, Alga-fl Yorks. 1
p. 106 ; Him, Desm. Finnland, 1903, p. 22 ; West & G. S. West, Further
Contrib. Plankton Scott. Lochs, 1905, p. 504 ; British Freshw.

104 BRITISH DESMIDIACE^E.

plankton, 1909, p. 172 ; Wahlburg, Bidr. kiinne. Littois-trask, 1913,
p. 48.

Body of semicell smaller and relatively somewhat
narrower than in the type, processes very much longer
and very slender, rather more divergent and often
gracefully curved, about 1| times to twice as long as
the body of the cell.

? Zygospore globose and smooth, fuscous brown in
colour (Turner}.

Length, without processes, 26-29 \L ; with processes,
77-84 \L ; breadth, without processes, 15-17^; with
processes, 84-139 [i ; breadth of isthmus 8-9*5 \i ; diam.
zygosp. 12[j, (Turn.}.

ENGLAND.- -Plankton of Crummock Water, Cumber-
land ! Plankton of Hawes Water, Grasmere, Stickle
Tarn and Windermere, Westmoreland ! Strensall, N.
Yorks ! Plankton of pools in Button Park, Warwickshire !

WALES. — Capel Curig ! (Cooke & Wills), Carnarvon-
shire. In the plankton !

SCOTLAND.- -Loch Hempriggs, Caithness ! ; Poolewe,
Ross ; Dallas, Moray ; Glen Coe, Argyle (Roy & Biss.).
Rhiconich, Sutherland ! Loch Ness, Inverness ! Common
in the plankton of Sutherland, Ross, Inverness, Perth,
Lewis and Harris, Outer Hebrides, and of the Orkneys

i/

and Shetlands !

ICELAND.- -Donegal ! Galway ! Kerry! Plankton of
Mayo, Galway, Kerry, Lough Neagh, and of Lough Beg,
Londonderry !

Geogr. Distribution. — Germany. Galicia and Austria.
Servia. Norway. Sweden. Finland. Poland. Iceland.
Central China. Turkey-in-Asia. Australia. Canada.
Colombia.

This variety is most commonly found in plankton, although
not exclusively confined to such a habitat. It is a frequent
constituent in plankton samples from many parts of the world,
and is generally distributed in the British lakes, occurring in
some cases in such great abundance as to form the dominant
constituent of the phytoplankton.

The zygospore figured by W. B. Turner, 1893, for this variety

STAURASTRUM. 105

does not correspond at all with the description given by Roy &
Bissett for the zygospore of the type. It is evident that if both
these records be accurate, var. longipes should not be placed as
a variety of St. paradoxum, but, because of its very different
zygospore, should be considered a distinct species. Whilst
further knowledge of the zygospores is to be desired before
coming to a definite conclusion, the writer is inclined to the
opinion that the zygospore figured by Turner quite possibly did
not belong to St. paradoxum var. longipes Nordst.

Var. cingulum West & G. S. West. (PI. CXLV,

figs. 9, 10.)

St. paradoxum var. cinfjulum West & G. S. West, Scott. Freshw. Plankton, I,
1903, p. 548, t. 18, f. 6, 7.

Base of semicell subcylindrical and narrower than
in the type, and with a ring of about 12 minute papillae,
of which 7 are visible across the base in the front view ;
apex of semicell straight or slightly convex ; processes
longer and more slender than in the type, gracefully
curved upwards.

Length, without processes, 32-40 p ; including pro-
cesses, 71-81 pt ; breadth, without processes, 16-23 [x ;
including processes, 64-77 JJL ; breadth at base of semi-
cell, 11 '5-1 2 [A ; breadth of isthmus 7*5-8-5 [i.

ENGLAND.— Plankton of Hawes Water, Westmoreland !

WALES.- -In the plankton.

SCOTLAND.— Plankton of Lochs Shin and Morar,
Sutherland!, Loch Rosque, Ross!, Lochs Katrine and
Achray, Perth!, and in the plankton of the Orkneys
and Shetlands !

IRELAND.— Plankton of Loch Currane, Kerry !

Geogr. Distribution.—- Norway. Australia.

This variety is exclusively confined to plankton, and is not
-at all universal in its distribution. It is distinguished by the
narrow cylindrical base of the semicells, furnished with a ring
of about a dozen minute spines. The processes are longer than
in the typical form and are gracefully curved upwards,
body of the semicell is frequently covered with small granules,
similar to those on the processes and arranged in concent™
rings round the base of each process. In length and in curvature

106 BRITISH DESMIDIACE^;.

the processes are similar to those of St. paradoxum var. longipes
Nordst.

Var. nodulosum West. (PI. CXLVI, fig. 1.)

St. paradoxum var. nodulosum West, Alg. W. Ireland, 1892, p. 182, t. 23,.
f. 13.

A smaller variety with its processes trifurcate at the
apices ; cells in vertical view triangular, lateral margins
with two undulations.

Length with processes, 33 \L ; without processes, 14 (/. ;
breadth, with processes, 27 '5-30^ ; breadth of isthmus

5 (/..

IRELAND.- -Upper Lake of Killarney, Kerry !
Var. parvum West. (PL CXLV, fig. 6.)

St. paradoxum forma parva West, Alg. W. Ireland, 1892, p. 182, t. 23, f. 12 ,-
Roy & Biss. Scott. Desm. 1894, p. 23 : West & G. S. West, Alg. S. England,.
1897, p. 496.

? St. paradoxum var. longipes forma minor Istvanffi, Diag. praev. Alg. nov.
Hungar. 1887, p. 11.

Cells similar to the type form but exceedingly minute.

Length, without processes, 9-1 6 {/. ; with processes,
18-35 (A ; breadth, with processes, 20-28 (JL ; breadth of
isthmus 3 '5-6 [I.

ENGLAND.- -Thursley Common, Surrey ! Keston Com-
mon, Kent ! New Forest, Hants !

SCOTLAND. — Common (Roy & Biss.}. Ehiconich,,
Sutherland !

IRELAND. --Near Glenties and Sproule's Lough, Done-
gal ! Ballynahinch, Galway ! Adrigole, Cork !

Geogr. Distribution.- -Finland. Hungary ?

The dimensions given by Istvanffi for his St. paradoxum var.
longipes forma minor agree with those of var. parvum West, and
forma minutissima of Heimerl (' Desm. alpin.' 1891, p. 607) also
seems to be very similar to this variety. Figures were in neither
case given, unfortunately ; but Schmidle's figure of forma minutis-
sima Heimerl ('Beitr. Alg. Alp.' 1895, 1. 16, f. 16) does not exactly
correspond with var. parvum West. It is possible, however,
that both f. minor Istv. and f. minutissima Heimerl are synony-
mous with var. parvum West.

STAURASTRUM. 107

Var. evolutum W. £ G. S. West. (PL CXLV, figs.

7,8.)

St. tetracerum var. evolutum West & G. S. West, Freshw. AK Orkneys &

Shetlands, 1905, p. 25, t, 2, f. 31.
St. paradoxum var. G. S. West in manuscript.

Cells very small, about 1^ times longer than broad,
excluding the processes, with a minute excavation at
the sinus ; processes long, diverging and often curved ;
in vertical view triangular, sides distinctly convex,
angles produced into long processes.

Length, without processes, 10-11 (i ; with processes,
27-40 (JL ; breadth, without processes, 7 '5-9 '5 \L \ with
processes, 26-50 \L ; breadth of isthmus 4*5 JJL.

SCOTLAND.- -In the plankton, Shetlands !

This variety is distinguished from var. longipes Xordst. by its
much smaller size, and its semicells of different proportions, as
well as by its convex sides in the vertical view. The latter
character and the longer processes readily distinguish it also
from var. parvum West. The length of the processes is subject
to considerable variation, and the cells are invariably twisted
so that the angles of the one semicell alternate with those of
the other.

113. Staurastrum pseudopelagicum W. & G-. S. West.

(PL CXLV, figs. 11, 12.)

St. paeudopdarjicum West & G. S. West, Scott. Freshw. Plankton, I, 1903,
p. 547, t. 18, f. 1-3 ; Further Contrib. Freshw. Phytoplank. Scott. Lochs,

1905, p. 504 ; Freshw. Alg. Orkneys & Shetlands, 1905, p. 27.
St.pseudopelaqicum VSLT. bifurcation Huitfeldt-Kaas, Plankton Xorske Vande,

1906, p. 154, t. 2, f. 34, 35.

Cells rather under medium size, about Ij times
broader than long, including the processes, deeply con-
stricted ; sinus open, acuminate at its apex ; semicells
obversely semicircular, apex only very slightly convex,
angles produced to form short, stout, diverging processes
tipped with 2 strong diverging spines ; cell- wall rough
with granules arranged in concentric series round the
processes ; vertical view triangular, sides slightly con-

108 BRITISH DESMLDIACE^E.

cave or convex, angles produced to form short thick
processes.

Zygospore unknown.

Length, without processes, 27-34*5 pi ; with processes,
57-71 {JL ; breadth, without processes, about 20-30 [i ;
with processes, 63-86*5 (j. ; breadth of isthmus 7*5-13 pi.

ENGLAND.- -Plankton of Stickle Tarn and Winder-
mere, Westmoreland !

WALES.- -In the plankton !

SCOTLAND. --Plankton of Lochs Shin, Morar and Ruar,
Sutherland ! Loch Shiel, Inverness ! Loch Tay, Perth !
Loch Stranabhat and 7 other lochs in Lewis, and in Loch
a Bhursta, Benbecula, Outer Hebrides ! Plankton of
Loch Kirbister, Orkneys.

IRELAND. — Plankton of Lough Gall, Achill Isle,
Mayo ! Kerry !

Geogr. Distribution. --Norway. Canada.

This species may be compared with some forms of St. para-
doxum Meyen, but it is readily distinguished by its shorter
processes, which are terminated by two large divergent spines
in the same vertical plane.

St. pseudopelagicum var. bifurcation Huitfeldt-Kaas has pre-
cisely the same characters as typical St. pseudopelagicum. The
form mentioned by the same author as typical St. pseudopela-
gicum, the processes of which, according to him, are terminated
by 3 spines each, is possibly a form of St. paradoxum Meyen.
Some of the British specimens, however, have been observed
by Prof. G. M. Smith of Wisconsin, U.S.A., to possess processes
which end in 3 spines, and on one occasion the processes were
tipped with one spine only. The species has so far only been
found in plankton.

114. Staurastrum inflexion Breb.
(PI. CXLIII, figs. 7, 8.)

Staurastrum inflexum Breb. Liste Desm. 1856, p. 140, t. 1, f. 25 ; Arch, in
Pritch. Infus. 1861, p. 742 ; Cooke, Brit. Desm. 1887, p. 169, t. 58, f. 5 ;
De Toni, Syll. Alg. 1889, p. 1208; West, Alg. Engl. Lake Distr. 1892,
p. 20 ; Roy & Biss. Scott. Desm. 1894, p. 21 ; West & G. S. West, Alg.
S. England, 1897, p. 495 ; Alga-fl. Yorks. 1902, p. 105.

St. margaritaceum var. inflexum Rabenh. Flor. Europ. Alg. 1868, p. 207.

STAURASTRUM. 109

Cells small, about Ij times broader than long, includ-
ing the processes, deeply constricted, sinus rectangular,
widely open ; semicells subcuneate. ventral margin
tumid, much more convex than the dorsal, semicells
gradually attenuated at the angles to form long, slender,
slightly incurved processes, tipped with 2 or 3 very
minute spines and provided with several concentric
series of minute denticulations. Vertical view triangular,
sides concave, angles produced into slender denticulate
processes, and with a row of tiny granules just within
each lateral margin. Cells often twisted about the
isthmus, so that the processes of one semicell alternate
with those of the other.

? Zygospore spherical, with numerous slender pro-
cesses twice dichotomous at the apex.*

Length 21 '7-26(1 ; breadth, without processes, 14-15 a ;
including processes, 30-40 ^ ; breadth of isthmus 5-7*5 (JL.

ENGLAND.- \Yestmoreland ! (Biss.), and in the plank-
ton of Codale Tarn ! Lancashire ! W. & N. Yorks !
Cheshire and Leicester (Roy). Essex ! Cambs !
Warwicks ! and in the plankton of Bracebridge Pool,
Sutton Park ! Worcester ! Surrey ! Kent ! Hants !
(Roy). Devon ! (Harris). Cornwall !

WALES.— Snowdon !, Capel Curig ! (Cooke & Wills] y
and Llyn Ogwen !, Carnarvonshire. Llyn Coron, Angle-
sea ! Ffestiniog, Merioneth !

SCOTLAND.— General ! (Roy & Biss.}. Near House of
Hill, Wigtown ! Orkneys and Shetlands !

IRELAND.— Donegal ! " Clare Isle, Mayo ! Galway !
Kerry! Dublin and Wicklow (A rch.). Down! London-

V

derry 1

Geogr. Distribution.- -France. Germany. Switzerland.
Galicia in Austria. Portugal. Norway. Japan.

St. inflexum is a much commoner species than its ally St..

* Amongst the papers of the late Professor West is a drawing of a zygospore
by the late Dr. Lutkemiiller, who suggests that it is possibly St. brachycerum
From a study of the empty semicells surrounding the zygospore, however the
writer is inclined to attribute it to St. inflexum Breb. It was of
described above (see PI. CLXVII, f. 7).

110 BRITISH DESMIDIACE^E.

brachycerum. It is readily distinguished from the latter species
by its longer and more slender processes, which are not so
strongly incurved. The ' body ' of the cell is also relatively
smaller, and not as broad in proportion with the length of cell.

115. Staurastrum crenulatum (Nag.) Delp.
(PL CXLIII, figs. 9-13.)

Phycastrum (Stenactinium) crenulatum Nag. Gatt. einz. Algen, 1849, p. 129,

t. 8 B, a.
Staurastrum crenulatum Delp. Spec. Desm. subalp. 1877, p. 164, t. 12,

f. 1-11 ; Wolle, Desm. U. S. 1884, p. 126, t. 42, f. 26-29 ; Schmidle, Beitr.

Alp. Alg. 1895, p. 36 ; G. S. West, Variation Desm. 1899, p. 393, t. 11, f.

21-27 ; Borg. Alg. Faeroes, 1901, p. 234, t. 7, f. 16 ; Cushman in Bull.

Torr. Bot. Club, 30, 1903, p. 564; Teodor. Mater, flor. alg. Rouman.

1907, p. 185.

Cells small, about as long as broad, sometimes a little
longer or shorter according to the relative length of the
processes, constriction deep, sinus acute, nearly rect-
angular, often minutely acuminate at the apex ; semi-
cells broadly oval or subfusiform, apex broad, truncate
or slightly convex, and often somewhat elevated,
sometimes with a pair of verruca? ; ventral margin very
tumid ; semicells gradually attenuated bo form hori-
zontal processes of varying length, with more or less
denticulate undulate margins, denticulations near the
apex of the semicell often tending to become emar-
ginate. Vertical view 3-5-angular, sides concave, with
a pair of emarginate verrucse just within the margin ;
angles produced to form denticulate processes.

Zygospore unknown.

Length 20-25 \L ; breadth, including the processes,
20-33 u. ; breadth of isthmus 5-7 \L.

ENGLAND. --Roundhay Park, Leeds, and Cautley
Spout, W. Yorks ! Pilmoor and Stokeley, N. Yorks !
Dernford Fen, Cambs ! Burnham Beeches, Bucks !
Near Goring, Oxford ! Warwicks ! and in the plankton
of Bracebridge Pool, Button Park! Worcester ! (Griffiths).
Uxbridge, Middlesex ! Tliursley Common, Surrey !

WALES. — Capel Curig, Carnarvonshire (Roy).

SCOTLAND. — Pretty common (Roy & Biss.). Orkneys !

STAURA STRUM. 1 1 1

IRELAND. — Dublin and Wicklow (Arch.). Lough
Derryadd, Armagh ! Skady and Kam's Islands, Lough
Neagh !

Geogr. Distribution. — Germany. Eoumania. Italy.
Sicily. Norway. Sweden. Finland. Faeroes. Japan.
E. Africa. United States. Newfoundland.

The relative length of the processes seems to be very variable
in this species, and there also seems to be considerable variation
in the strength of the granulation. After carefully studying
specimens from Yorkshire, Prof. G. S. West decided that the
relatively broader individuals with longer processes are usually
more strongly developed as regards the spines, whilst specimens
with short processes have their emarginate warts very much
reduced (see 'Variation Desm.' 1899, p. 393). Some specimens
have much in common with St. margaritaceum var. ornatum
Boldt.

116. Staurastrum neglectum G. S. West.
(PL CXLII, figs. 16-18.)

St. income var. ft Ralfs, Brit. Desm. 1848, p. 134, t. 34, f. 8, b, c, and d ;

Cooke, Brit, Desm. 1887, p. 168, t. 64, f. 5.
St. hexacerum var. /3 Wittr. Gotl. 6l. sotv. Alg. 1872, p. 52 ; Roy & Biss.

Scott. Desm. 1893, p. 21 ; West & G. S. West, Alg. S. England, 1897,

p. 495.
St. neglectum G. S. West, Alg. Yan Yean, 1909, p. 70, t. 3, f. 12.

Cells small, Ij-lj times broader than long, including
the processes ; constriction extremely small, scarcely
visible ; lower part of semicell shortly cylindrical, upper
part incudiform, apex of semicell convex, angles pro-
duced to form attenuated processes, provided with
minute granules arranged in horizontal series. Vertical
view triangular, " body : small, sides concave, angles
produced into fairly long, attenuated, straight, or
slightly curved processes, which are provided with
6 or 7 rows of minute denticulations ; processes some-
what dilated towards their apex, which is tipped with
3 minute spines. Cells usually twisted, the processes
of one semicell alternating with those of the other.

Zygospore spherical, with slender processes 2 or 3
times forked at the apex, and with slightly inflated bases.

112 BRITISH DESMIDIACE^.

Length 23 '5-26^ ; breadth, with processes, 32-35 (JL ~
breadth of median part of cell 6 '5-7 ^ ; diam. zygosp.,
without processes, 20-22*5 [JL ; length of processes about
20 fji.

ENGLAND. — Sussex (Rolfs). Halgavor Moor and Ky-
nance Valley, Cornwall ! (Rolfs). Kare, but widely
distributed in British Isles !

Geogr. Distribution. — Sweden. United States. Australia.

This species differs from St. hexacerum (Ehr.) Wittr. (— St.
tricorne Ralfs) in the smaller " body ' of the semicells, the
cylindrical median part of the cells, with the faintest indication
of a constriction, and in the more elongate processes. The latter
are also much more elegant, and are dilated towards the extremi-
ties. The appendages of the zygospores of St. neglectum are
also more complicated than those of St. hexacerum.

117. Staurastrum dubium West.
(PL CXLVI, fig. 4.)

Staurastrum dubium West, Alg. N. Wales, 1890, p. 19, f. 28 ; Cushman in
Bull. Torr. Bot. Club, 1904, p. 583 ; ibid., 1907, p. 614.

Cells rather over medium size, nearly twice as broad
as long, including the processes, deeply constricted ;
semicells fusiform, rough with rather flattened granules,

* CP ^^

base of semicell with a ring of granules ; processes
inflexed, with tricuspid apices ; vertical view triangular,
lateral margins concave, with a row of granules just
within the margin ; centre of apex smooth.

Zygospore unknown.

Length 40 fi ; breadth 70 pi ; breadth of isthmus 13 p.

WALES. — Capel Curig, Carnarvonshire !

Geogr. Distribution.- -United States.

118. Staurastrum boreale W. & G. S. West.
(PL CXLVI, fig. 5.)

Staurastrum boreale West & G. S. West, Freshw. Alg. Orkneys and Shetlands,
1905, p. 27, t. 2, f. 25.

Cells small, about Ij times broader than long, includ-
ing the processes, constriction fairly deep ; semicells

STAURASTRUM. 113

somewhat cup-shaped, upper angles produced to form
long, nearly horizontal or slightly diverging processes,
each provided with 4 series of denticulations, and with
3 spines at the extremity ; apex of semicell very slightly
produced, nearly straight and with acute emarginate
granules ; base of semicell with a circle of 11-13 den-
ticulations, of which 6 or 7 may be seen in the front view.

J «/

Vertical view triangular, sides nearly straight, with
3 emarginate verrucse along each, and with 3 others just
within each lateral margin.

Zygospore unknown.

Length 27-29 JJL ; breadth, with processes, 43-46 [JL ;
breadth of isthmus 7 '5-8 (JL.

SCOTLAND.- -Plankton of Loch Asta, Shetlands !

This species has only been recorded from one locality,
where it occurred in considerable abundance. It is not very
closely allied to any other British species, and should be com-
pared with. St. Burmense Turn, and St. galeatum Turn, (vide W.
& G. S. West, 'Freshw. Alg. Ceylon,' 1902, p. 190, t. 22, f. 19).

119. Staurastrum Pseudosebaldi Wille.
(PL CLXVI, fig. 4.)

Staurastrum Pseudosebaldi Wille, Norges Ferskv. Alg. 1880, p. 45, t. 2, f. 30 ;
\Volle, Desm. U. S. 1884, p. 139, t, 46, f. 8, 9 ; De Toni, Syll. Alg. 1889,
p 1178 ; Borge, Siissw. Chlor. Archang. 1894, p. 38 ; W. & G. S. West,
A\v S. England, 1897, p. 496 ; Borg. Alg. Faeroes, 1901, p. 235, t. 7,
f. 17 ; West & G. S. West, Alga-fl. Yorks. 1902, p. 106 ; Cushman in
Rhodora, 1903, p. 224.

Cells of medium size, about 1 £ times broader than long,
including the processes ; body of cell slightly constricted,
sinus an acute notch; semicells cuneate, slightly
campanulate at the base, widening towards the apex,
lateral margins concave ; upper angles produced into
stout horizontal processes, each tipped with three spine
and rough with several concentric series of granules
apex of semicell with a row of regular bifid spines
base of semicell with a series of distant granules ot which
3 are visible. Vertical view triangular, lateral margins

VOL. V.

114 BRITISH DESMIDIACE^.

concave, with a series of projecting emarginate spines,
and a further row of spines just within the margin ; angles
produced into granulate processes.

Zygospore unknown.

Length about 51 [JL ; breadth, including processesy
about 60 [Ji ; breadth of isthmus 12 pi.

ENGLAND. — Pilmoor, N. Yorks ! Thurslev Common.

«/

Surrey !

Geogr. Distribution.- - C4ermany (var.). Galicia in
Austria. Norway. Poland. N. Russia. Faeroes. Green-
land. Siberia (var.). India. New Zealand (var.). United
States.

St. Pseudosebaldi differs from St. Manfeldtii in the distant
granules at the base of the semicell, and in the spiny lateral
margins in the end view. From St. Sebaldi var. ornatum it is-
distinguished by its shorter processes and the bifid spines which
project from the lateral margins in the end view.

Var. simplicius West. (PL CXLIX, fig. 13.)

St. Pseudosebaldi var. simplicius West, Alg. Engl. Lake Distr. 1892, p. 21,
t. 9, f. 37.

Cells smaller than in the type, with the apical spines
simple instead of emarginate ; processes shorter, tipped
with 3 spines longer than usual.

Length, with spines, 32 [i ; breadth 46 pi ; breadth of
isthmus 9 \i .

ENGLAND. — Brandreth, Westmoreland !

120. Staurastrum Manfeldtii Delp.
(PL CXLVIII, fig. 2.)

Staurastrum Manfeldtii Delp. Spec. Desm. subalp. 1877, p. 160, t. 13,.
f. 6-19 ; De Toni, Syll. Alg. 1889, p. 1214 ; Gutw. Flor. Glon. Okolic
Tarnapola, 1894, p. 108 : Llitkem. Desm. Central China, 1900, p. 123 ;
Comere, Desm. de France, 1901, p. 158, t, 11, f. 8 ; West & G. S. West.
Alg. N. Ireland, 1902, p. 56 ; Freshw. Alg. Orkneys & Shetlands, 1905y
p. 27 ; Brit, Freshw. Phytoplankton, 1909, p. 175 ; Hustedt, Desm. et
Bacill. Tirol. 1911, p. 339.

Cells of medium size, about Ij times broader than
long, including the processes ; constriction small ; semi-

STAURASTRUM. 115

cells subcimeate or cup-shaped, broadening towards the
apex, which is slightly convex and provided with a row
of emarginate or irregular verruca ; upper angles pro-
duced to form tapering processes tipped with 3 minute
spines, and covered with several series of denticulations
which are sometimes continued over the body of the
semicell itself, processes slightly converging or nearly
horizontal. Vertical view usually triangular, sides
straight, or very slightly convex, angles produced to form
processes with slightly undulating margins, with a series
of emarginate verrucae just within each lateral margin.

Zygospore unknown.

Length 42-57^; breadth, including processes, 55-
100'S (I ; breadth of isthmus 9-13 p.

ENGLAND.- -Plankton of Ennerdale Water, Cumber-
land! and Malham Tarn, W.Yorks! Plankton of Brace-
bridge Pool, and Windmill Pool, Shirley, Warwickshire !

SCOTLAND. — Plankton of Lochs Sandy, Trebister,
Beosetter and Bressay, Shetlands !

IRELAND.- -Xear Lough Magrath, Donegal ! Plankton
of Lough Accorymore, Achill Isle, Mayo ! Ballynahinch,

Gal way !

Geoc/r. Distribution- -France. Galicia and Austria.
Italy. Norway. Siberia. Central China. India. Australia.

In the originally described Italian specimens the apical verrucas
were very much more irregular in size and form than in the
British examples, and near the origin of each process there was
a longer conspicuous spinous verruca. In the British specimens
the verrucse are all more or less of the same size, and form quite
a regular series. There is a further difference in the British
examples in the presence of delicate granules, either in scattered
groups, or forming a circular band round the base of the semicelL

The species is not infrequent in plankton gatherings.

Var. annulatum W. & G. S. West. (PL CXLVIII,

% 3.)

St. Manfeldtii var. annulatum West & G. S. West, Alg. N. Ireland, 1902,
p. 56, t. 1, f. 30, 31.

Processes slightly narrower than in the type ; apical

116 BRITISH DESMIDIACE.E.

verrucse somewhat reduced ; with a double series of
granules round the base of the semicell.

Length 46-49 (JL ; breadth, including processes, 63-70 pt ;
breadth of isthmus 10'5 pi.

IRELAND. — Near Lough Magrath, Donegal !

The double ring of granules round the base of the semicells
and the slight reduction of the apical emarginate warts are
characters which at once distinguish this variety. It bears a
certain resemblance to St. Pseudosebaldi Wille, but the body of
the plant is relatively larger, and the granulation is different.
In the vertical view the sides are quite smooth, all the verru-
cations being within the margin as in typical St. Manfeldtii.

121. Staurastrum Duacense W. & G. S. West.
(PL CXLVIII, fig. 1.)

Staurastrum Pseudosebaldi subsp. duacense West, Alg. W. Ireland, 1892,

p. 184, t. 24, f. 1.

St. bicorne ? Borge, Sverig. Chlor. II, 1895, p. 24, f. 15.
St. Duacense W. & G. S. West, Brit. Freshw. Phytoplankt. 1909, p. 202.

Cells of medium size, nearly twice as broad as long,
including the processes, constriction fairly deep, sinus
acute ; semicells cuneate, broadening towards the apex,
not inflated at the base, but sometimes with a minute
granule on each lateral margin near the sinus ; a.pex
broad and straight, with a row of emarginate verrucse ;
angles produced to form long, horizontal processes, bifid
at their extremity ; dorsal margin of processes verrucose,
verrucae reduced to simple denticulations towards the
tips ; ventral margin of processes similarly ornamented.
Vertical view oval, the poles produced to form long
processes tipped with a spine, margins smooth, with a
series of emarginate verrucse just within. Chloroplast
axile with a central pyrenoid and 5 or 6 ridges.

Zygospore unknown.

Length 32-38 \L ; breadth, including processes, 55-67 pi ;
breadth of isthmus 9-11 \L ; greatest thickness 18 JJL.

IRELAND. — Ballynahinch and Roundstflne, Galway !

Geogr. Distribution. — Scandinavia.

STAURASTRUM. 117

This species is only known in the British Isles from one
locality in western Ireland, and is apparently one of those
species which can only flourish in waters draining from the older
and harder palaeozoic rocks. It is very similar in appearance to
St. PseudosebaUi Wille var. bicorne Boldt ('Sibir. Chloroph/
1885, t. 6, f. 36), but differs in the more complicated lateral
margins of the semicells.

It also differs from St. Pseudosebaldi var. tonsum Nordst.
('Freshw. Alg. Xew Zealand/ 1888, p. 36, t. 4, f. 4) in the non-
fusiform shape of the end view as well as in its stronger apical
warts. St. bicorne Hautpfl. ? forma Borge (' Sverig. Chloroph.' II,
1895, p. 24, t. 1, f. 15) is a form of St. Duacense, differing only in
its rather larger size and in the apical teeth of the processes.

122. Staurastrum bicorne Hauptfl.
(PI. CXLIII, fig. 17.)

St. bicorne Hauptfl. Zellmembr. u. Hiillgallerte Desm. 1888, p. 37, t. 3,
f. 21, 24, 27 ; Borg. Bornholm. Desm.-fl. 1889, p. 148, t. 6, f. 9 ; De Toni,
Syll. Alg. 1889, p. 1210; Roy & Biss. Scott. Desm. 1893, p. 17; Him,
Desm. Finnl. 1903, p. 19 ; Cedergren, Sverig. sotvattensalg. 1913, p. 23.

Cells of medium size, about 1| times broader than
long, including the processes, sinus becoming very wide
towards the exterior ; semicells subtriangular, rapidly
widening towards the apex, sides concave, apex very
slightly convex, angles of semicell gradually attenuated
to form fairly long, stout, and nearly horizontal processes,,
which are provided with several series of denticulations,.
and are bifid (?) at their apex ; upper margin of face
with two transverse series of about 5-8 verrucae. Ver-
tical view narrowly fusiform, lateral margins verrucose
in the middle and with another series of verrucae just
within each margin ; processes with denticulations.

Zygospore unknown.

Length 52 (i ; breadth, including processes, 72 jj. ;
thickness 18*5 {/. ; breadth of isthmus 13*4 pi.

SCOTLAND.- -Birsemore Loch, Aberdeen (Roy & Biss.).

Geogr. Distribution. Germany. Bornholm (var.).
Finland. Sweden. Australia (var.).

118 BRITISH DESMIDIACE^:.

123. Staurastrum subgracillimum W. & G. S. West.

(PL CXLIV, figs. 1, 2.)

St. subgracillimum West & G. S. West, Some N. A. Desm. 1896, p. 263, t. 17,
f. 3, 4 ; Alg. N. Ireland, 1902, p. 56, t. 1, f. 21, 22 ; Alg. Ceylon, 1902,
p. 186 ; Further Contr. Freshw. Phytopl. Scott. Lochs, 1905, p. 504 ;
Brit, Freshw. Phytoplankton, 1909, p. 202.

Cells small, about as long as broad, excluding the
processes ; semicells broadly cuneate, sides straight, apex
distinctly concave, upper angles produced to form very
long slender processes, which are nearly horizontal, and
of the same width throughout their whole length, with
margins minutely undulate. Vertical view triangular
or quadrangular, sides straight or very slightly concave,
angles produced to form long processes, the apices of
which are furnished with 3 spreading teeth ; processes
denticulate, cell-wall otherwise smooth. Cells often
twisted at the isthmus.

Zygospore unknown.

Length lG'5-15'5 VL ; breadth, without processes,
10-1 3 (ji ; with processes, 40-60 y* ; breadth of isthmus
4-8-6 (x.

SCOTLAND. --Khiconich, Sutherland! Plankton of
small loch near Cearnabhal, Lewis, Outer Hebrides !

IRELAND .--Near Glenties, Co. Donegal !

Geogr. Distribution. — Ceylon. United States.

The distinctive features of this species are the concave apex,
and the long slender parallel processes. In the British Isles it is
a very rare Desmid, and is confined to bogs and lakes of the
' western ' area.* The British examples all differ from the
original American specimens in their rather more robust processes,
and in their very minute apical spines. Both the American and
Ceylon specimens were provided with three larger spreading
teeth, all lying in the same horizontal plane.

124. Staurastrum tetracerum Ralfs.
(PL CXLIX, figs. 2, 3.)

? Micrasterias tetracera Kiitz. Syn. Diat. 1834, p. 74, t. 7, f. 83, 84.
Binatella tetracera Breb. Alg. Falaise, 1835, p. 269.

* Seep. 18.

STAURASTRUM. 119

ytaurastrum paradoxum Ehr. Inf. 1838, p. 143, t. 10, f. 14.

<S7. tetracerum Ralfs, in Ann. Mag. Xat. Hist. 1845, v. 15, p. 150, t. 10, f. 1 ;

Brit. Desm. 1848, p. 137, t. 23, f . 7 ; De Bary, Conj. 1858, p. 71 ; Arch.

in Pritch. Infus. 1861, p. 744 ; Rabenh. Krypt,-fl. Sachs. 1863, p. 191 ;

Lund. Desm. Suec. 1871, p. 68 ; Xordst, Norges Desm. 1873, p. 35 ; Delp.

Spec. Desm. subalp. 1877, p. 161. t. 11, f. 25-28; Kirchn. Alg. Schles.

1878, p. 168 ; Cooke, Brit, Desm. 1887, p. 182, t. 63, f . 5 ; De Torn, Syll.

Alg. 1889, p. 1232 ; West, Alg. W. Ireland, 1892. p. 187 : Alg. E.igl. Lake

Distr. 1892, p. 21 ; Roy & Biss. Scott. Desm. 1893, p. 26 ; West & G. S.

West, Alg. Madag. 1895, p. 80 ; Alg. S. England, 1897. p. 495 : Liitkem.

Desm. C. China, 1900, p. 124 ; Comere, Desm. de France, 1901, p. 160,

t. 11, f. 7; West & G. S. West, Alga-fl. Yorks. 1902, p. 104; Freshw.

Alg. Orkneys & Shetlands, 1905, p. 25 ; Alg. Third Tanganyika Expedit.

1907, p. 127 ; Kaiser, Alg. Traun. u. Chiem. 1914, p. 153.
Phycastrum paradoxum Kiitz. Spec. Alg. 1849, p. 180 (in part).
^t'liirnstrum paradoxum var. tetracerum Rabenh. Flor. Europ. Als. 1868,

p. 210.

-S'/. Arachne var. tetracerani Jacobs. Desm. Danemark, 1875. p. 208.
St. tetracerum var. unil«l<itn,n West & (J. S. West, Ale. Madag. 1895, p. 80,

t. 9, f. 6.
vSV.. fjracillimum var. bir(nli>i/iiin Bolilin, Flor. Alcol. d'eau douce d'Acores,

1901, p. 55, t, l,f. 12.

Cells minute, about as long as broad, or up to 1 5- times
longer than broad, including the processes; constriction
fairly deep, sinus open with a minutely excavated apex ;
semicells short and rectangular, apex straight or slightly
concave, upper angles produced to form long, strongly
diverging processes, gradually attenuated towards their
apices, and with 4 or 5 undulations ; apex of processes
minutely emarginate. Vertical view fusiform with the
poles drawn out to form nodulose processes. Cells often
twisted at the isthmus.

Zygospore globose, with about 16 long processes
swollen at the base, and once or twice dichotomous at
the apex (Lund.).

Length, without processes, 7-10pi ; with processes,
24-28 pi ; breadth, including processes, 18-30 PL ; breadth
of isthmus 4-5 pi ; diam. zygosp., without processes, 16 u ;
with processes, 30 pi.

ENGLAND. — Cumberland ! Westmoreland ! Lanca-
shire ! W., K, and E. Yorks ! Cheshire (Roy). Leicester
(Roy). Norfolk ! Warwicks ! Worcester ! Gloucester
(Ralfs). Surrey ! Sussex (Ralfs). Kent ! Hants ! (Roy).
Wilts ! Devon ! Cornwall !

WALES. — General (often abundant) ! In the plankton !

120 BRITISH DESMIDIACE^E.

SCOTLAND. — General! (Roy & Biss.). Not uncommon

in the plankton ! Orkneys ! In the plankton, Shetlands !

IRELAND. — Donegal ! Mavo and Clare Isle ! Galway !

o */ ^

Kerry ! Dublin and Wicklow (Arch.).

Geogr. Distribution.- -France. Germany. Switzerland.
Galicia and Austria. Hungary. Italy. Turkey. Norway.
Sweden. Denmark. Bornholm. Central and S. Russia.
Faeroes. Iceland. Greenland. Siberia. Central China.
Japan. Ceylon. Burma, Australia. Madagascar.
Central Africa. Abyssinia. Azores. United States.
Guiana. Colombia. Brazil. Patagonia.

Forma trigona Lund. (PL CXLIX, fig. 4.)

St. tetracerum forma trigona Lund. Desm. Suec. 1871, p. 69 ; West, Alg.
W. Ireland, 1892, p. 187 ; West & G. S. West, Alg. S. England, 1897,
p. 495 ; Alg. Orkneys & Shetlands, 1905, p. 25.

Cells in end view triradiate.

Dimensions as in the biradiate form.

ENGLAND. - -Lancashire ! Burnham Beeches, Bucks!
Surrey ! Hants ! Devon ! Cornwall !

WALES.- -Llyn Idwal and Moelfre, Carnarvonshire !

SCOTLAND.- -Bhiconich, Sutherland ! Bressay, Shet-
lands !

IRELAND. — Mayo and Clare Isle ! Galway ! Kerry !

Geogr. Distribution. — Sweden.

Forma tetragon a W. & G. S. West.

St. tetracerum forma tetragona West & G. S. West, Alg. S. England, 1897,
p. 495.

Cells in end view 4-radiate.
ENGLAND.- -Koughton Moor, Cornwall !

Staurastrum tetracerum is a very characteristic and easily
recognised species with a world-wide distribution. The biradiate
form is the commonest ; the 3- and 4-radiate forms are com-
paratively rare.

Bohlin ('Flor. Algol, d'eau douce d'Acores,' 1901, p. 56, f. 12)
has described and figured a rather large form of this species
under the name of St. gracillimum var. biradiatum. The same
author has also figured (fig. 13) a specimen intermediate in form

STAURASTRUM. 121

between this species and St. bibrachiatiim Reinscli var. cymatium
AVest (= : Dichotomum bibrachiatiim W. & G. S. West var. cyma-
tium). A reduced form of the latter species has also been
described and figured by West & G. S. West ('Alg. Madag.' 1895,
p. 74, t. 8, f. 28 a' and b'). Bohlin criticises the creation of the
new genus Dichotomum in view of the discovery of such forms
as these, which obviously link it up with Staurastrum. It must
be pointed out, however, that practically all divisions between
allied genera are more or less arbitrary, and that as a rule no
hard and fast line can be drawn between them. This is particu-
larly true in the case of the Desmidiacea3, and species forming
links between other genera of the group have already been noted
in this work (see vol. ii, p. 126 ; vol. iv, p. 89). Nevertheless
no one would desire, for example, that the genus Arihrodesmus
be abolished because it is closely linked up with some forms of
Staurastrum. In the same way it will probably be very con-
venient to retain the genus Dichotomum also, although it is very
closelv allied to Staurastrum.

«/

Var. validum W. & G. S. West. (PL CXLIX, fig. 5.)

Xt. tetmcerum var. ralidum West & G. 8. \Yest, Alg. S. England, 1897,
p. 495, t. G, f. 25.

A rather larger form, with the body of the cell rela-
tively longer ; processes stouter and not at all attenuated,
with 5 undulations.

Length, without processes. 18 [/. ; with processes, 42 u :
breadth, without processes, 13 UL ; with processes,
breadth of isthmus 5 (JL .

ENGLAND. — Near Chapel Wood, Surrey !

125. Staurastrum iotanum Wolle.
(PL CXLIX, fig. i.)

.in iotanum Wolle, Desm. U. S. 1884, p. 137, t. 51, f. 5-7; De Toni,
Syll. Alg. 1889, p. 1147 ; West, Alg. N. Wales, 1890, p. 20 ; Roy & Biss.
Scott. Desm. 1893, p. 21 ; Turn. Alg. E. India, 1893, p. 132, t. 22, f. 12 ;
West & G. S. West, Alg. S. England, 1897, p. 495 ; Desm. U. S. 1898,
p. 314, t. 18, f. 14, 15 ; Alg. Ceylon, 1902, p. 185.

Cells very minute and inconspicuous, slightly broader
than long, including the processes, constriction fairly
deep, sinus small, acute-angled and open ; semicells

122 BRITISH DESMIDIACE.E.

subrectangular, lower angles not rounded, practically
rectangular, apex very slightly convex, upper angles
produced to form long diverging processes, with 2 or 3
undulations and emarginate apices ; vertical view tri-
angular, sides nearly straight, angles produced into long
nodulose processes ; cell- wall smooth.

Zygospore unknown.

Length, without processes, 8-10 JJL ; including pro-
cesses, 1 3-20 (ji ; breadth, without processes, 6-9 \i ;
including processes, 13-21 fi ; breadth of isthmus 3*5-

4(JL.

ENGLAND.- -Puttenham Common, Surrey !

WALES. — Capel Curig, Carnarvonshire !

SCOTLAND. --Near Girnoc, Aberdeen (Roy & Biss.).
Spital of Glen Shee, Perth ! Rhiconich, Sutherland !

Geogr. Distribution. — Sweden (var.). Poland. Ceylon.
United States.

126. Staurastrum pseudotetracerum (Nordst.)

W. & G. S. West.

(PL CXLIX, fig. 11.)

Staurastrum contortum var. pseudotetracerum Nordst. in Botan. Notiser,
1887, p. 157 ; Freshw. Alg. New Zeal. 1888, p. 37, t. 4, f. 9 ; De Toni,
Syll. Alg. 1889, p. 1231 ; West, Alg. W. Ireland, 1892, p. 183.

St. pseudotetracerum West & G. S. West, Alg. Madag. 1895, p. 79, t. 8, f. 39 ;
Desm. U. S. 1898, p. 314 ; Bohlin, Flor. Alg. d'eau douce d'Acores. 1901,
p. 58, t. 1, f. 16 ; West & G. S. West, Alga-fl. Yorks. 1902, p. 104 ; Alg.
Ceylon, 1902, p. 185.

Cells very small, about as long as broad, including
the processes, deeply constricted, sinus widely open,
broadly triangular in outline; semicells cuneate, apex
nearly straight, or slightly convex or concave, upper
angles produced to form short, strongly diverging pro-
cesses tipped with 3 very minute spines ; processes
rough with subacute granules arranged in concentric
series. Vertical view triangular or quadrangular, sides
concave, angles produced to form granulose processes.

Zygospore unknown.

Length, without processes, 12-19(i ; with processes,

STAURASTRUM. 123

19-25 [j. ; breadth, including processes, 19-30 ku. ; breadth
of isthmus 5-6 ^ .

ENGLAND. — Skipwith Common, N. Yorks !

SCOTLAND.- -Benbecula, Outer Hebrides !

IRELAND.- -Lakes, near Recess, Gahvay !

Geogr. Distribution. — Sweden (var.). Ceylon. Siam
(var.). New Zealand. Madagascar. Azores. United
States.

This little species is readily distinguished from St. tet racer um
by the relatively larger body of the semicell, and its stouter
habit. From St. micron West it is distinguished by its cuneate
semicells, and its more slender processes with several series of
granules.

127. Staurastrum micron West.
(PL CXLIX, fig. 6.)

Staurastrum micron West & G. S. West, New and Tut. Kreslnv. Alu\ 1896,
p. 159, t. 4, f. 50, 51 ; Alg. S. England, 1897, p. 495 ; Freshu . ( 'hlorophy.
Koh Chang, 1901, p. 95 ; Alg. X. Ireland, 1902, p. 57,

Cells very small, about as long as broad, including the
processes, deeply constricted ; semicells inversely semi-
circular, apex slightly convex ; upper angles produced
to form short, stout, diverging processes, each process
with two series of short spines near its base, and dilated
at its apex, which is truncate and provided with 3 short
spines. Vertical view triangular, sides concave, angles
produced to form short dilated processes.

Zygospore unknown.

Length, without processes, 8*5-1 1*5 \L ; with processes,
12-17'5pi; breadth, without processes, 7-9'ojx; with
processes, 12'5-19pt ; breadth of isthmus 3-3'5^.

ENGLAND.- -Puttenham Common, Surrey (abundant) !
Woodbury Common, Devon !

IRELAND.- -Near Glenties, and Lough Gartan, Done-
gal !

Geogr. Distribution. — Sweden (var.). Siam (form).
W. Africa (var.).

This tiny species has very constant characters which render

124 BRITISH DESMIDIACE^E..

it easy of distinction. It is nearest to St. pseudotetracerum West,
but is much smaller, its processes are shorter and more robust,
and the spines at the dilated apices of the processes and two
rings of short spines at their base distinguish it.

128. Staurastrum latiusculum W. & G. S. West.

(PL CXLIX, fig. 8.)

Staurastrum latiusculum West & G. S. West. Alg. N. Ireland, 1902, p. 53,
t. 1, f. 20.

Cells small, about li times broader than long, includ-
ing the processes, constriction fairly deep, sinus open,
broadly semi-elliptical ; semicells inversely trapeziform,
apex slightly convex, lower angles rectangular, upper
angles produced to form fairly long, distinctly diverging
processes, each with three denticulate undulations and
tipped with 3 minute spines. Vertical view quadrangular,
sides slightly concave, angles produced to form long
denticulate processes, with a conspicuous small spine
on each side at the base of each process.

Zygospore unknown.

Length, without processes, 13[i; with processes,
19-23fji ; breadth, without processes, about 13-1 3 'opt ;
with processes, 32 \L ; breadth of isthmus 9 (i.

IRELAND. — Near Glenties, Co. Donegal !

The distinctive characters of this species are its small size, its
relatively broad body with a small semi-elliptical sinus, and the
paired spines at the base of each process.

129. Staurastrum pelagicum W. & G. S. West.

(PI. CXLVI, fig. 6.)

Staurastrum pdagicum West & G. S. West, Freshw. Alg. N. Ireland, 1902,
p. 46, t. 2, f. 26, 27 ; Comp. Study Plank. Irish Lakes, 1906, p. 86 ;
Ostenf. & Wes.-Lund, Fortnightly Explor. Plankton Icelandic Lakes,
1906, p. 1111 ; Borge in Botan. Notiser, 1913, p. 49.

Cells of medium size, 1-g- times broader than long,
without the processes, deeply constricted, sinus open,
but becoming very narrow towards its apex ; semicells

STAURASTRUM. 125

oblong-elliptic, the ventral margin more convex than
the dorsal, angles produced to form short, stout, diverging
processes, externally smooth, and quite solid, with deeply
bifurcated apices. Vertical view triangular, sides slightly
concave, angles produced to form short solid processes,
bifurcate at the apex. Cell-wall covered with granules
arranged in about 4 distant series round the angles,
minutely punctate between the granules.

Zygospore unknown.

Length, without spines, 34-40 pi ; breadth, without
spines, 38-47 pi ; with spines, 64-75 u ; breadth of
isthmus 12'5-13pi.

SCOTLAND.- -Plankton of the Orkneys and Shetlands !

IRELAND.- -Plankton of Lough Corrib, Galwav ! Louoii

1 « O

Neagh ! Lough Beg, Londonderry !

Geogr. Distribution. — Sweden (form). Iceland (form).

This species, which only occurs in plankton, is perhaps nearest
to St. Avicula Breb. It differs from that species, however, in
its much larger size and in the peculiar, solid, deeply bifurcate
processes, which are directed slightly upwards. The two spines
of St. Avicula are attached more or less independently to the
body of the Staurastrum, whereas the much larger spines of St.
pelagicum are the two divisions of a very deeply divided but
solid process. It is also closely allied to St. pseu(lopelagic"/n
W. & G. S. West, but is distinguished by its more elliptical
semicells and solid processes. The processes of St. pseudo-
pelagicum are hollow, but the terminating spines of the two
species are very similar.

130. Staurastrum polymorphum Breb.
(PI. CXLII, fig. 24 ; PL CXLIII, figs. 1-3.)

St. polymorphum Breb. in Ralfs, Brit. Desm. 1848, p. 135, t. 22, f. 9, t. 34, f. G ;
Arch, in Pritch. Infus. 1861, p. 742, t. 2, f. 20, 21, 24, 25, 31 ; Rabenh.
Krypt.-fl. Sachs. 1863, p. 192 ; De Not. Desm. Ital. 1867, p. 52, t. 4, f. 46 ;
Rabenh. Flor. Europ. Alg. 1868, p. 209 ; Delp. Spec. Desni. subalp.
1877, p. 162, t. 11, f. 56-62 ; Kirchn. Alg. Schles. 1878, p. 167 ; Wille,
Ferksv. Alg. Nov. Semlj, 1879, p. 53 ; Wolle, Desm. U. S. 1884, p. 126,
t. 42, f. 9, 10, 24, 25 ; Cooke, Brit. Desm. 1887, p. 169, t. 58, f. 4 ; Boldt,
Desm. Gronland, 1888, p. 38 ; Hansg. Prodr. Alg. Bohm. 1888, p. 213 ;
De Toni, Syll. Alg. 1889, p. 1208 ; Anderss. Sverig. Chlor. 1890, p. 12 ;
Giitw. Flor. Glondw Okolic Lwowa, 1891, p. 68; Flor. Glonow Galic.

126 BKITISH DESMIDIACE^E.

1892, p. 30 ; West, Alg. W. Ireland, 1892, p. 181 ; Roy & Biss. Scott.
Desm. 1893, p. 23 ; Liitkem. Desm. Attersees, 1893, p. 567 ; W. & G. S.
West, Alg. S. England, 1897, p. 495 ; Borge, Siisswasseralgen Franz
Josefs Land, 1899, p. 763 ; Comere, Desm. de France, 1901, p. 157, t. 13,
f. 13 ; West & G. S. West, Alga-fl. Yorks. 1902, p. 105 ; Freshw. Alg.
Orkneys and Shetlands, 1905, p. 26 ; Gutw. Flor. Alg. Mont. Tatrensium,
1909, p. 475; Georgev., Desm. Macedon. 1910,' p. 244; Hustedt, Desm.
Tirol, 1911, p. 340.

Didymidium (Staurastrum) polymorphum Reinsch, Algenfl. Frank. 1867,
p. 165 (in part).

Cells small, about Ij times broader than long, includ-
ing the processes, constriction moderately deep, sinus
acute and almost rectangular, sometimes minutely
acuminate at its apex ; semicells variable in form,
subelliptical, subfusiform or even subcuneate, ventral
margin usually more strongly convex than the dorsal ;
semicells attenuated at the angles to form short stout
processes, horizontal or very slightly incurved, tipped
with 3 or 4 minute spines and provided with 3 or 4 series
of minute denticulations ; ' body : of semicell also
granulate, granules arranged in concentric series round
the angles. Vertical view usually 3- (-7-) angular, the
two semicells of the same individual often differing in the
number of processes, lateral margins very slightly con-
cave ; centre of apex smooth. Chloroplast axile, with
a central pyrenoid in each semicell, and a pair of lobes
extending into each angle.

Zygospore spherical or somewhat angular, with stout
processes, branched at the apex.

Length 21-29 [L ; breadth, including processes, 21-
43 (X ; breadth of isthmus 6-8 ^ ; diam. zygosp., without
processes, 30 (JL ; including processes, 55 pi.

ENGLAND. — Cumberland ! and in the plankton of
Ennerdale Water ! Westmoreland (Bissett) ! Lancashire
(Roy). W., N., and E. Yorks! Cheshire (Roy). Leicester
(Roy). Essex! Warwicks (Wills) !, and in the plankton
of Bracebridge Pool, Button Park ! Worcester (Griffiths) !
Surrey ! Sussex (Rolfs}. Hants (Bennett) \ Dartmoor,
Devon (Harris). Cornwall ! (Marquand).

WALES.- -Bethesda, Llyn Idwal, Snowdon, Capel
Curig, Llyn Bochlwyd, Moel Siabod, and Llyn-y-cwm-

STAURASTRUM. 127

ffynon. Carnarvonshire ! Ffestiniog ! and Dolgelly
( Rolfs ) , Merioneth .

SCOTLAND. — General and variable (Roy & Biss.).
Ross ! Inverness ! Aberdeen ! Perth ! Argyle ! Lewis
and Harris, Outer Hebrides ! Orkneys and Shetlands !
Rare in the plankton !

IRELAXD.- -Donegal ! Mayo and Clare Isle ! Galway !
Kerry ! Dublin and Wicklow (Arch.). Armagh !

Geogr. Distribution.- -France. Germany. Switzerland,
Galicia and Austria. Hungary. Italy. Servia. Mace-
donia. Norwav. Finmark. Sweden. Denmark. Fin-

u

land. Poland. X. and S. Russia. Russian Lapland.
Faeroes. Xova Zembla. Franz Josef's Land. Spits-
bergen. Greenland. Siberia. Mongolia. Japan. Ceylon.
Central Africa. United States and Alaska. Canada.
West Indies. Patagonia.

This small and very variable species has an almost world-wide
distribution.

Var. pusillum West. (PL CXLIII, fig. 4.)

M. /><>lt(nn>fj,/tnn> var. piixilliim \\Vst, Clare Isl. Alg. 1912, p. i'."-.

Cells much smaller, processes thinner and slightly
inflexed ; " body : of semicell similar in form to the
type.

Length 18-1 8 '5 u..

IRELAND. — Clare Isle, Mayo !

Var. subgracile Wittr.

«SV. polymorphum var. subgracile Wittr. Gotl. Ol. sutv. Alg. 1872, p. 51 ;
De Toni, Syll. Alg. 1889, p. 1209 ; West, Alg. W. Ireland, 1892, p. 181 ;
Liitkera. Desm. Attersees, 1893, p. 567 ; Kaiser, Algenfl. Traunstein u.
Chiemgau, I, 1914, p. 153.

Processes longer than in the type, semicells in vertical
view triangular, angles produced, lateral margins con-
cave.

Length 22*5-28 \i ; breadth, including processes,
30-45 (j. ; length of processes, 6-12 [i ; breadth of isth-
mus 8-9 u..

128 BRITISH DESMIDIACE^.

IRELAND. --Derryclare Lough, and lakes E. of Lough
Bonn, Co. Gal way !

Geogr. Distribution. — Austria. Bornholm. Scan-
dinavia. Siberia.

Figures of this variety have never been published, but Witt-
rock, in describing it, says that it is very similar to t. 22, f. 9 g,
in Kalfs, 'Brit. Desm.' and t. 8 B, f. n, o, p in 'Nag. Gatt. einz.
Alg.' 1849. Its distinguishing feature seems to be that the
processes are longer. It may be that this variety is merely a
form of St. cremdatum.

Var. simplex W. & G. S. West. (PL CXLIII, fig. 5.)

St. polymorplmm var. simplex West & G. S. West, Freshw. Alg. Orkneys
& Shetlands, 1905, p. 26, f. 28.

Cells relatively longer than in the type, not including
the processes ; processes very slightly divergent, with
one circle of denticulations, and the apex of each tipped
with 4 minute spines ; cell- wall otherwise quite smooth.
Vertical view quadrangular.

Length, without processes, 21-23 JJL ; breadth, without
processes, 12*5-15 \L ; with processes, 23-28'5 \L ; breadth
of isthmus 7*6 \L.

SCOTLAND. — Near Lerwick, Shetlands !

Var. munitum West. (PI. CXLIII, fig. 6.)

>S7. polymorphum var. munitum West, Alg. Engl. Lake Distr. 1892, p. 20,
f. 35 ; Schmidle, Lappmark Siisswasseralgen, 1898, p. 60 (forma).

Processes provided with 3 or 4 series of sharp denticu-
lations ; cells in vertical view triangular, sides straight.

Length 31 (JL ; breadth, with processes, 36 ^ ; breadth
of isthmus 8 {ju

ENGLAND. — Esthwaite Water, Lancashire !

Geogr. Distribution. — Sweden (form).

131. Staurastrum affine W. & G. S. West.
(PL CXLII, fig. 23.)

,S7. affine West & G. S. West, Freshw. Alg. Orkneys and Shetlands, 1905,
p. 26, t. 2, f. 27.

STAURASTROI. 129

Cells rather under medium size, slightly longer than
broad, including the processes, constriction fairly deep ;
semicells elliptic-subsemicircular. ventral margin strongly
convex, dorsal margin slightly so, angles produced to
form short thick processes, slightly divergent, terminated
by 4 short spines, and with 2 or 3 circles of strong
denticulations. Vertical view triangular, sides slightly
convex, angles produced into short thick processes,
which are distinctlv denticulate. Cell-wall rough with

«/ o

minute granules, arranged in concentric series round the
base of the processes.

Zygospore unknown.

Length, without processes, 37-40 [JL ; breadth, without
processes, about 29-33 u. ; breadth, with processes,
44-55 [i ; breadth of isthmus 10'5 JJL.

SCOTLAND.- -Plankton of Xeugles Water and Loch
Brindister, Shetlands !

This species was found in abundance in the plankton of the
above-mentioned lakes. Its distinctive characters are the large
size of the " body" of the semicells., and the short, outwardly
diverging processes, each of which possesses 2 rings of denticu-
lations and 4 apical spines. It is perhaps nearest to St. poly-
morphum Breb., but is larger, of different relative proportions,
and with different processes.

132. Staurastrum proboscidium (Breb.) Arch.
(PI. CXLIII, figs. 14-16.)

Staurastrum aspcrum var. proboscidium Breb. in Ralfs, Brit. Desni. 1848,

p. 139, t. 23, f. 12, b, c.
St. proboscidium Arch, in Pritch. Infus. 1861, p. 742 ; Jacobs. Desm. Danein.

1875, p. 206 ; Cooke, Brit, Desm. 1887, p. 173, t. 59, f . 6 ; De Toni,

Syll. Alg. 1889, p. 1215 ; Comere, Desm. de France, 1901, p. 151, t. 11,

f. 10 ; West & G. S. West, Freshw. Alg. Orkneys and Shetlands, 1905,

p. 28 ; Borge, Botan. Notiser, 1913, p. 31.
Didymidium (Staurastrum} polymorphum Reinsch. Algenfl. Frank. 1867,

p. 165 (in part).
Staurastrum hexacerum v. ornatum Borge, Siissw. Chlor. Archang. 1894,

p. 37, t. 3, f. 43 (form).
St. Borgeanum Schmidle, Lappm. Siisswasseralgen, 1898, p. 60, t. 3, f. 7 ;

West & G. S. West, Notes Alg. II, 1900, p. 297, t. 412, f. 10 ; Alga-fl.

Yorks. 1902, p. 106.
? St. proboscidium var. subglabrum West, Alg. N. Wales, 1890, p. 19, f. 35.

VOL. V. 9

130 BRITISH DESMIDIACE^:.

Cells of medium size, about as long as broad, including
the processes, but sometimes either slightly longer or
shorter than broad ; deeply constricted, sinus acute,
opening widely, with a minute excavation at its apex :
semicells subelliptical or subcuneate, apex and lateral
margins slightly convex ; angles prolonged to form
short stout horizontal processes, which are truncate at
their apices, tipped with a circle of minute granules,
and with several concentric series of granules
beneath ; upper part of faces of semicell with several
longitudinal series of granules, the uppermost granule
of each series being developed into an emarginate
verruca ; base of semicell with a circle of simple
granules. Vertical view triangular, sometimes quad-
rangular ; sides concave, with a series of emarginate
verrucse just within the margin ; angles slightly pro-
duced into short truncate processes ; centre of apex
smooth.

Zygospore unknown.

Length 35-45 (JL ; breadth 30-53 ji ; breadth of isth-
mus 10-11 '5 u.

ENGLAND. — Loughrigg, Westmoreland ! Cam Fell,.
W. Yorks ! Bog near Widdale Beck, N. Yorks ! Epping
Forest, Essex ! New Forest, Hants (Bennett}. Near
Chapel Wood, Surrey ! Dartmoor, Devon (Harris).
Near St. Just, Cornwall !

WALES.- -Llyn Ogwen, Carnarvonshire !

SCOTLAND.- -Ross, Inverness, Aberdeen, Kincardine,
Forfar, C41en Logie!, Perth, Fife, and Arran(/?o?/ & Biss.).
Orkneys ! Shetlands !

IRELAND. --Dublin and Wicklow (Arch.).

Geogr. Distribution.-- France. Austria (var.). Norway.
Sweden. Finland. Denmark. Bornholm. Spitzbergen.
Greenland. Siberia (var.). Central China (var.). Java.
Central Africa. New Zealand (var.). Brazil (var.).

There seems little doubt that St. Borgeanum Schmidle is
identical with. St. proboscidium (Breb.) Arch., although the
figures in Ralfs, 'Brit. Desm.' are not particularly good. The
British specimens are often not exactly typical, being charac-

STAURASTRUM. 131

terised by their very slightly concave or even straight margins
in the end view, and somewhat shorter and more broadly trun-
cate processes. West in 'Alg. N. Wales,' 1890, p. 90, f. 35, des-
cribed a variety subglabrum of this species, which seemed to be
almost destitute of granules. This variety has never been
observed since it was first described, and the original figure of
it scarcely gives a clear idea of its exact nature. Accordingly,
for the present, it must be considered a doubtful form.

133. Staurastrum margaritaceum (Ehrenb.) Menegh.

(PL CL, figs. 5-9.)

Pentaslerias margaritaceum Ehrenb. Infus. 1838, p. 144, t. 10, f. 15.
Staurastrum margaritaceum Menegh. Synops. Desm. 1840, p. 227 ; Ralfs
in Ann. Mag. Nat. Hist. vol. 15, 1845, p. 157, t. 11, f. 7 ; Brit. Desm.

1848, p. 134, t. 21, f. 9 ; Breb. Liste Desm. 185(5, p. 140 ; Arch, in Priteh.
Inf. 1861, p. 744, t. 3, f. 34, 35 ; De Xot, Desm. Ital. 1867, p. 53, t. 5,
f. 48 ; Rabenh. Flor. Europ. Alg. 1868, p. 206 ; Xordst. Xorges Desm.
1873, p. 28 ; Desm. Arctote, 1875, p. 33 ; Kirchn. Alg. Schles. 1878,
p. 166 ; Gay, Mono. loc. Conj. 1884, p. 68 ; Wolle, Desm. U. S. 1884,
p. 125, t, 41, f. 31-35 ; Cooke, Brit. Desm. 1887, p. 181, t. 64, f. 12 ;
Hansg. Prodr. Alg. Bohm. 1888, p. 212 ; De Toni, Syll. Alg. 1889, p. 1227 ;
West, Freshxv. Alg. X. Vorks. 1889, p. 6, t. 291," f. 11; Freshw. Alg.
N. Wales, 1890, p. 20, t. 6, f. 22 ; Alg. W. Ireland, 1892, p. 186 ; Alg.
Engl. Lake Distr. 1892, p. 21 ; Borge, Chlor. Xorske Finmark, 1892,
p. 8 ; Roy & Biss. Scott. Desm. 1893, p. 22 ; West & G. S. West, Xew and
Int. Alg. 1896, p. 160, t, 4, f. 36 ; Alg. S. England, 1897, p. 496 ; Liitkem.
Desm. Millstattersees, 1900, p. 22 ; Comere, Desm. de France, 1901,
p. 158, t. 11, f. 18 ; West & G. S. West, Freshw. Chloroph. Koh Chang,
1901, p. 95 ; Alga-fl. Yorks. 1902, p. 108 ; Borge, Sao Paulo Alg. 1918,
p. 50.

Phycastrum margaritaceum Kiitz. Plvyc. Germ. 1845, p. 138; Spec. Alg.

1849, p. 181.

Ph. (Stenactinium) margaritaceum Xag. Gatt. einz. Alg. 1849, p. 128.
Didymidium (Staurastrum) margaritaceum Reinsch, Alg. Frank. 1867,

p. 162 (in part).
Staurastrum angidosum Schmidt, Grimdl. Algenfl. Liineb. Heide, 1903,

p. 18, t. 1, f. 3.

Cells small, about as long as broad, or often slightly
longer, constriction not deep, sinus open ; semicells
variable in form, cup-shaped, subspherical or subfusi-
form, upper angles of the cell produced to form short
obtuse processes, projecting horizontally, or sometimes
slightly inflexed ; cell-wall rough with minute granules,
arranged in concentric series round the angles, some-
times with a distinct circle of granules round the base
of the semicell. Vertical view 3-9-angled, more often

132 BRITISH DESMIDIACE^.

4-, 5- or 6-angled, sides concave, centre of apex smooth,
angles produced to form short truncate processes.

Zygospore large and spherical, with numerous appen-
dages twice dichotomous at the apex.

Length 24-30 [JL ; breadth, including the processes,
16-48[x; breadth of isthmus 6-10^; diam. zygosp,,
without processes, 30 pt ; with processes, 50 ^ .

ENGLAND. - - Cumberland ! Westmoreland ! (Rolfs).
Lancashire ! W. and N. Yorks. (up to 2000 feet) !
Cheshire ; Leicester (Roy). Essex ! Warwicks (Wills).
Gloucester (Rolfs). Surrey (zygospores from Devil's
Jumps, Frensham Common) ! Sussex (Rolfs). Hants !
(Roy). Devon ! (H orris). Cornwall! (Morquond).

WALES. — Abundant (at 2000 feet on Glyder Fach) !

SCOTLAND. — General ! (Roy & Biss.). At 3500 feet
on Lochnagar, Aberdeen ! Orkneys ! Shetland? !

IRELAND. — Donegal ! Mayo and Clare Isle ! Gal way !
Kerry ! Dublin and Wicklow (Arch.). Antrim !
Londonderry !

Geogr. Distribution.- -France. Belgium. Germany.
Switzerland. Galicia and Austria. Hungary. Norway
and Finmark. Sweden. Finland. N. Russia. Spitz-
bergen. Greenland. Siberia (var.). Japan. India. Siam.
Java. Celebes. Tasmania. Azores (var.). Sandwich
Islands. United States. Brazil.

St. margaritaceum occurs commonly in this country, and has
a very wide distribution. It is frequently found in association
with St. muricatum. Variations in connection with the granules
on the apex of the semicell are very common, and apart from
forms having the definite granulation of var. coronulatum or
var. fdbustum, specimens are not uncommon in which some of
the granules surrounding the apical smooth, area of the semicell
are very strongly developed, duplicated, or emarginate, so that
the apex of the cell in the front view is more complicated than
usual.

Var. coronulatum West. (PL CL, fig. 10.)

St. margaritaceum var. coronulatum West, Alg. N. Wales, 1890, p. 20, f. 3 ;
Liitkem, Desm. Millstattersees, 1900, p. 22 ; West & G. S. West, Alg. N.
Ireland, 1902, p. 57.

STAURASTRUM. 133

Apex of semicell truncate, with a circle of small
granules.

Length 25 '5 u. ; breadth 20-27 [i ; breadth of isthmus
8[i.

WALES.- -Llyn Padarn, Llyn Idwal, Rhyddu, bog
above Capel Curig Lakes and bog between Glyder Fach
and Lluffwy, Carnarvonshire !

o \j J

IRELAND.- -Loughs Clogher and Dunlewy, Donegal !
Slievecommedagh, Down !

Geogr. Distribution. — Austria. Scandinavia.

Var. hirtum Nordst. (PI. CL, fig. 11.)

St. margaritaceum var. hirtum Nordst. Alg. et Char. I, 1880, p. 11, t. 1,
f. 18 ; Lagerh. Sverig. Desm. 1883, p. 54 ; Borg. Desm. Brasil, 1890,
p. 46 (forma) ; West, Alg. W. Ireland, 1892, p. 186 ; Borge, Sao Paulo
Alg. 1918, p. 50.

A variety in which the granules ornamenting the
cell-wall, including those at the apices of the processes,
are developed into short spines.

Length 38 p ; breadth 44 ^ ; breadth of isthmus 12 JJL.

WALES.- -Yr Orsedd, Carnarvonshire !

IRELAND. — Carrantuohill, Kerry ! Castletown, Cork !

Geogr. Distribution. — Scandinavia. Finland. Australia.
Java. Brazil.

Var. robustum W. & G. S. West. (PI. CL, fig. 13.)

St. margaritaceum var. robustum West & G. S. West, Alg. S. England, 1897,.
p. 496, t. 7, f. 14 ; Freshw. Chlorophy. Koh Chang, 1901, p. 95.

Cells stouter than in the type, semicells, without
the processes, broadly elliptical, not constricted at the
base of the processes, but tapering gradually into them ;
in vertical view 4- or 5-radiate, with a small emarginate
verruca on either side of the base of each process.

Length 25*5 pi ; breadth 27 [i ; breadth of isthmus 8 (JL,

ENGLAND.- -Uxbridge, Middlesex !

Geogr. Distribution.- -Koh Chang, Siam.

This variety approaches St. ornatum Turn. (— St. margari-
acemn var. ornatum Boldt), but has much shorter and stouter

134 BRITISH DESMIDIACE^.

processes. It may also be compared with. St. foliatum Turn.,
but Turner's figure is too indistinct to admit of a detailed
comparison.

Var. subcontortum W. & G. S. West. (PL CL, fig. 12.)

St. margaritaceum var. subcontortum West & G. S. West, Alg. S. England.
1897, p. 496, t. 17, f. 15-17.

Cells in vertical view 6- or 7-radiate ; processes trun-
cate and all curved in one direction as in St. cyrtocerum.
Length 26 [i ; breadth 25-27 [i ; breadth of isthmus

9(1.

ENGLAND.- -Devil's Jumps, Frensham, Surrey !

*

134. Staurastrum Chavesii Bohlin.
(PL CXLIX, fig. 12 ; PL CLXVI, fig. 1.)

Staurastrum Chavesii Bohlin, Flor. Algol, d'eau douce d'A5ores, 1901. p. 56,

f. 15.
? St. subtile Schmidle, Beitr. Alp. Alg. 1895, p. 37, t. 16, f. 12.

Cells small, about as long as broad, or up to 1^ times
broader than long, including the processes ; constriction
fairly deep, sinus rounded, almost semicircular ; semi-
cells inversely subtrapeziform, apex straight or slightly
concave ; upper angles of the semicell produced to form
short stout diverging processes, biundulate and denticu-
late, truncate at the apex, and with 4 tiny apical spines ;
lateral margins of semicell with conspicuous emarginate
protuberances at the point of origin of the processes.
Vertical view quadrangular, sides concave, angles pro-
duced into short nodulose processes ; apex with an
emarginate projection at the base of each process.

Zygospore unknown.

Length 10-17 pt ; breadth, including processes, 15-22^ ;
breadth of isthmus 6 '5-8 JJL.

IRELAND. --Near Ballynahinch, Galway !

Geogr. Distribution. — Austria . Azores .

The distinctive characters of this species are the obtuse sinus
and the four emarginate processes on the dorsal surface, one at

STAURASTRUM. 135

the base of each process. These are not very distinct in
PL CXLIX, fig. 12, but can be recognised in fig. 1, PL CLXVI.

135. Staurastrum cyrtocerum Breb.
(PL CXLIX, fig. 9 ; PL CL, fig. 4.)

~<t lurastrum cyrtocerum Breb. in Ralfs, Brit. Desm. 1848, p. 139, t. 22, f. 10 ;
Arch, in Pritch. Infus. 1861, p. 742 ; Rabenh. Krypt.-fl. Sachs. 1863,
p. 191 ; Wittr. Gotl. Ol. sotv. Alg. 1872, p. 51 ; Wolle, Desm. U. S.
1884, p. 128, t. 42, f. 30, 31 ; Cooke. Brit. Desm. 1887, p. 168, t. 58, f. 3 ;
De Toni, Syll. Alg. 1889. p. 1207 ; West, Ale. X. Wales, 1890, p. 18, f. 16 ;
Alg. W. Ireland, 1892, p. 181 ; Alg. Engl. Lake Distr. 1892, p. 20 ; Roy
A: Biss. Scott, Desm. 1893, p. 19 ; Comere, Desm. de France, 1901, p. 155,
t. 11, f. 17; W.^t \ <;. S. West, Alga-fl. Yorks. 1902, p. 104; Alg. N.
Ireland, 1902, p. 53 ; Borge, in Botan. Xotiser, 1913, p. 32.

Phycastrum cyrtocerum Kiitz. Spec. Alg. 1849, p. 180.

JStaurastrum polymorphism var. cyrtocerum Rabenh. Flor. Europ. Alg. 1868,
p. 210.

Cells rather under medium size, usually somewhat

«/

broader than long, including the processes, deeply con-
stricted, sinus rectangular, acute ; semicells cup-shaped,
ventral margin very tumid, dorsal margin convex, often
with a row of minute emarginate granules visible, espe-
cially in slightly tilted specimens, upper angles produced to
form short stout converging processes, gradually tapering
towards their apices, which are tipped with 2 or 3 minute
spines ; cell-wall rough with minute granules, arranged
in concentric series round the angles, and in longitudinal
rows across the face of the semicell, median row incom-
plete ; cells often twisted about the isthmus. Vertical
view triangular or quadrangular, sides concave, with a
TOW of minute emarginate granules just within each
lateral margin; angles produced into short processes,
which are often abruptly bent, all in one direction.

Zygospore orbicular, with spines slightly forked at the
apex (Ralfs).

Length 23-39 [JL ; breadth, including processes, 33-
60 [i ; breadth of isthmus 8-11 [i.

ENGLAND. — Cumberland ! Westmoreland ! X. and
H. Yorks ! Cheshire (Roy). Burnham Beeches, Bucks !
Gloucester (Ralfs). Surrey! Sussex (Ralfs). Hants'.
i>3von! (Harris). Cornwall!

136 BRITISH DESMIDIACEJE.

WALES. — Dolbadarn Castle, Capel Curig ! (Cooke
Wills), Llyn Idwal, Llyn-y-cwm-fTynon, Llyn Bodgyn-
wyd and near Conway, Carnarvonshire ! Holyhead.
Anglesea ! Dolgelly, Merioneth !

SCOTLAND. — Shetlands, Sutherland !, Ross, Inverness,.
Banff, Aberdeen, Kincardine, Forfar, Perth and Argyle ;
zygospores from Scotston, Aberdeen (Roy & Biss.),
Lewis, Outer Hebrides ! Hoy, Orkneys ! In the plankton f

IRELAND. - -Donegal ! Mayo and Clare Isle ! Gal way !
Kerry ! Dublin and Wicklow (Arch.). Down !

Geogr. Distribution. - France. Galicia in Austria,
Turkey. Norway. Sweden. Denmark. Bornholm. Fin-
land. N.Russia. Spitzbergen. Turkey in Asia. Australia.
LTnited States. Colombia. Brazil.

This species is very closely allied to St. bracliycerwn and St.
inflexum. It is a larger Desmid than either of these, however,
and the row of tiny emarginate granules on the apex of the semi-
cell is one of its distinguishing characters. Its short, stout,
converging processes, frequently seen in the vertical view to be
bent abruptly in one direction, are very characteristic.

Var. compactum W. & G. S. West. (PL CXLIX,

fig. 10.)

St. cyrtocerum var. compactum West & G. S. West, Alg. Orkneys & Shetlands,,
1905, p. 26, t. 2, f. 29.

Body of semicell much larger in proportion, and
processes much shorter.

Length 36 [L ; breadth, including processes, 40 ^ ;
breadth of isthmus 1 1 (i .

SCOTLAND. --Plankton of Loch Trebister, Shetlands I

136. Staurastrum brachycerum Breb.
(PL CXLII, figs. 21, 22.)

Staurastrum brachycerum Breb. Liste Desm. 1856, p. 139, t. 1, f. 24 ; Arch.

in Pritch. Infus. 1861. p. 742 ; Roy & Biss. Scott. Desm. 1894, p. 180.
St. polymorphism var. brachycerum Rabenh. Flor. Europ. Alg. 1868, p. 210 ;

Borge, Siisswasseralgen Franz Josefs-Land, 1899, p. 764 ; Comere, Desin.

de France, 1901, p. 157, t. 11, f. 4.

STAURASTRUM. 137

Cells small, usually a little broader than lono\ includ-

«/ o^

ing the processes, deeply constricted, sinus acute and
widely open ; semicells almost globular, dorsal margin
convex, ventral margin much more turgid ; angles
produced to form short, stout, and strongly inflexed
processes, tipped with 2 or 3 minute spines and provided
with several concentric series of denticulations, which
become stronger more remote from the apices of the
processes, so that the apex of the semicell seems to be
spinous in the front view. Vertical view triangular,
sides slightly concave, angles rather acutely rounded,
with 3 or 4 series of denticulations, centre of apex smooth,
with a small but prominent spine just within each
lateral margin at the middle point. Cells usually
twisted at the isthmus.

? Zygospore unknown.*

Length 17-23^ ; breadth, without processes, 10-12 (JL;
with processes, 20-23 \L ; breadth of isthmus 5-7 y. .

ENGLAND.- Near Senen, Cornwall !

\\ ALES.- -Llvn Idwal, Carnarvonshire !

i

SCOTLAND. — Aberdeen, Kincardine, Forfar and Perth
(Eoy & Biss.).

IRELAND.- -Dublin and Wicklow (Arch.).

Geoyr. Distribution.- -France. Switzerland. Sweden.
Franz Josef's Land.

This species is not at all common. It is closely allied to St.
polymorphic in, but is distinguished by its very strongly inflexed
processes, and the stronger spine-like denticulations.

137. Staurastrum eboracense Turn.
(PL CXLIII, fig. 23.)

Staurastrum eboracense Turn. Desm. Xotes, 1893, p. 345, f. 1J.

Small, with 4 incurved arms, rounded at the ends ;
each arm with 3 or 4 rows of conical granules ; sides
sinuate ; sinus rounded. It has an apical corona of
little verruca? ; remainder, except arms, smooth (Turner).

Zygospore unknown.

* Cf. footnote p. 109 (St. inJJexum).

138 BRITISH DESMIDIACEJS.

Length 25 [i ; breadth 27 pi ; breadth of isthmus 7 [.i .
ENGLAND. — Strensall Common, N. E. Yorks. (Turn.).

138. Staura strum hexacerum (Ehr.) Wittr.
(PL CXLIL figs. 11-14.)

(?) Desmidium hexaceros Ehr. Org. Id. Raumes, 1834, p. 293 ; Inf. 1838,
p. 141, t. 10, f. 10.

Binatella tricornis Breb. Alg. Falaise, 1835, p. 57, t. 8.

Staurastrum tricorne Menegh. Synops. Desm. 1840, p. 225 ; Ralfs, Brit.
Desm. 1848, p. 134, t. 22, f. 11, t. 34, f . 8 a ; Arch, in Pritch. Infus. 1861,
p. 742 ; Nordst. Desm. Spetsb. 1872, p. 38 ; Delp. Spec. Desm. subalp.
1877, p. 145, t. 11, f. 48-50; Kirchn. Alg. Schles. 1878, p. 165; Wolle,
Desm. U. S. 1884, p. 126, t. 41, f. 36-38 ; Cooke, Brit. Desm. 1887, p. 167,
t. 58, f. 2 ; Nordst, Fresh w. Alg. N. Zealand, 1888, p. 41, West, Alg.
N. Wales, 1890, p. 18 ; Alg. Engl. Lake Distr. 1892, p. 20 ; Bohlin,
Flor. Alg. d'eau douce d'Agores, 1901, p. 59, f. 19.

Phycastrum tricorne Kiitz. Phyc. Germ. 1845, p. 137.

Ph. hexaceros Kiitz. Spec. Alg. 1849, p. 180.

Ph. (P achy actinium} tricorne Nag. Gatt. einz. Alg. 1849, p. 126.

Staurastrum hexacerum Wittr. Gotl. Ol. sotv. Ala;. 1872, p. 51 ; De Toni,
Syll. Alg. 1889, p. 1206 ; Turn. Freshw. Alg. E. India, 1893, p. 125 ;
Roy & Biss. Scott, Desm. 1893, p. 21 ; West & G. S. West, Alg. Mada-
gascar, 1895, p. 75 ; Welw. Afric. Freshw. Alg. 1897, p. 50 ; Alg. S.
England, 1897, p. 495 ; G. S. West, Alga-fl. Cambridge, 1899, p. 25 ; W.
& G. S. West, Alg. N. Ireland, 1902, p. 52 ; Alga-fl. Yorks. 1902, p. 52 ;
Freshw. Alg. Orkneys & Shetlands, 1905, p. 26 ; Freshw. Alg. Burma,
1907, p. 218.

Cells small, about ly times broader than long, deeply
constricted, sinus open and acute ; semicells fusiform or
subtriangular, both dorsal and ventral margins convex,
tapering towards the angles to form very short processes
which end in about 3 minute teeth ; cell- wall rough
with tiny granules, arranged in concentric series round
the angles, granules in the centre of the faces and on the
apex of the semicell much reduced. Vertical view usually
triangular, lateral margins concave, angles very slightly
turgid. Chloroplast axile, with a central pyrenoid in
each semicell.

Zygospore spherical, armed with numerous long and
stout conical spines, very broad at the base and bifid at
the apex.

Length 23-28 \L ; breadth, including processes, 27-
34 \L ; breadth of isthmus 7-8 \L ; diam. zygosp., without
spines, 30(jt ; length of spines, about 16[ju

ENGLAND. — Cumberland ! Westmoreland, and in the

STAURASTRUM. 139

plankton of Codale and Easedale Tarns ! Lancashire !
W., N., and E. Yorks ! Cheshire (Roy). Cambridge !
Warwicks ! Worcester ! Middlesex ! Surrey ! Sussex

•/

(Rolfs). Kent Hants ! (Roy}. Devon ! Cornwall !

WALES. — General and abundant ! In the plankton !

SCOTLAND. — General ! ; zygospores at Scotston Moor,
Aberdeen (Roy & Biss.). Near Lochmaddy, N. Uist,
Outer Hebrides ! Orkneys and Shetlands. and also in
the plankton !

IRELAND. • Donegal ! Mayo and Clare Island !
Galway ! Kerry, and in the plankton ! Dublin and
Wicklow (Arch.). Louth ! Armagh ! Lough Xeagh !
Londonderry !

Geogr. Distribution.- -France. Germany. Switzerland.
( Jalicia and Austria. Hungary. Italy. Norway. Sweden.
Bornhohn. N. Russia. Faeroes. Iceland. Nova Zembla.
Spitzbergen. Greenland. Siberia. Japan. Burma.
Siam (var.). Australia. New Zealand. Madagascar.
E. Africa. Azores. LTnited States and Alaska. Yukon.
Argentine. Patagonia.

St. hexacerum is a very frequent species in this country, and
has a world-wide distribution. There have been different views
as to the range of St. hexacentm (Ehr.) Wittr. and St. tricorne Ralfs.
The latter includes two distinct forms, and of late years the earlier
name hexacerum has been almost universally adopted. Xordstedt
(in 'Bot. Notiser,' 1906, p. 115) has suggested that Ralfs' name
tricorne should be adopted for the form described by Ralfs as
St. tricorne var. /3, but this Desmid has been fully described and
figured by the late Prof. G. S. West as St. neglectum.

Var. semicirculare Wittr. (PI. CXLII, fig. 15.)

St. hexacerum var. semicirculare Wittr. Gotl. Ol. sotv. Alg. 1872, p. 52,
t. 4, f. 9 ; De Toni, Syll. Alg. 1889, p. 1206 ; West & G. 8. West, Alga-fl.
Yorks. 1902, p. 104 ; Freshw. Alg. Orkneys & Shetlands, 1905, p. 20.

St. tricorne var. semicirculare West. Alg. W. Ireland, 1892, p. 180.

St. hexacerum var. semilunare Roy & Biss. Scott. Desm. 1893, p. 21.

Cells nearly twice as large as those of the typical
form ; semicells in front view subsemicircular ; in end
view triangular, with the sides slio'htlv concave, angles

»/o

acutely rounded.

140 BRITISH DESMIDIACE.E.

Length 39-41 ^ ; breadth 40-42 [j, ; breadth of isth-
mus 11 (JL.

ENGLAND. — Baildon Moor and Roundhay Park, Leeds,
W. Yorks !

SCOTLAND. — Whitestripes, Aberdeen ; near Clochnaben,
Kincardine (Roy & Biss.). Scalloway, Shetlands !

IRELAND.- -Derryclare Lough, Co. Galway !

Geogr. Distribution. — Sweden. Faeroes.

This variety is distinguished by its larger size, and its apex is
also much more convex than in the typical form.

139. Staurastrum Haaboeliense Wille.
(PL CXLII, figs. 19, 20.)

Staurastrum Haaboeliense Wille, Norges Ferskv. Alg. 1880, p. 42, t. 2, f. 27 ;
Wolle, Desm. U. S. 1884, p. 131, t. 42, f. 51-53 ; De Toni, Syll. Alg. 1889,
p. 1207 ; West, Alg. N. Wales, 1890, p. 18 ; Alg. W. Ireland, 1892, p. 181 ;
West & G. 8. West, Alg. N. Ireland, 1902, p. 52.

Cells small, about li times broader than long, deeply
constricted, sinus acute, opening widely ; semicells
narrow elliptic-fusiform, slightly attenuated at the
angles, forming short stout processes tipped with a
group of tiny spines, and with 3 or 4 concentric series of
denticulations. Vertical view triangular, sides slightly
concave, angles produced and truncate.

Zygospore unknown.

Length 15-1 8 [JL ; breadth 24-27 pi ; breadth of isth-
mus 5-7 [i .

ENGLAND. — Codale Tarn, Westmoreland !

WALES. — Capel Curig, Carnarvonshire !

IRELAND. --Near Glenties, Co. Donegal ! Ballyna-
hinch, Co. Galway !

Geogr. Distribution.- -Norway. Australia. United
States.

This species is distinguished from St. hexacerum by its relatively
shorter, fusiform semicells, and its rather stronger denticula-
tion.

STAURASTRUM. 141

140. Staurastrum Cerastes Lund.
(PL CL, fig. 16; PL CLI, fig. 1.)

Cerastes Lund. Desrn. Suec. 1871. p. 69, t. 4, f. 6; Wills in
Midland Naturalist, 1881, p. 16, t. 5, f. 8 ; Wolle, Desm. U. S. 1884, p. 133,
t, 43, f. 6, 7 ; Cooke, Brit. Desm. 1887, p. 173, t. 59, f. 3 ; De Toni, Syll.
Alg. 1889, p. 1213 ; Roy & Biss. Scott. Desm. 1893, p. 18 ; West & G. S.
West, Some N. Amer. Desm. 1896, p. 268, t. 18, f. 4 ; Desm. U. S. 1898,
p. 318 ; Brit. Freshw. Phytoplankton, 1909, p. 174.
Staurastrum sp. Archer in Quart. Journ. Micr. Sc. vol. 12, 1872, p. 202.

Cells of medium size, about as long as broad, or some-
times broader, constriction small, an acute notch ; semi-
cells almost cylindrical in the lower part, widening
considerably upwards ; apex strongly convex, lateral
angles produced to form stout processes, attenuated
towards their apices, and gracefully incurved so that
the processes of the two semicells are nearly in contact ;
upper margin of process verrucose (in some aspects the
apex of the semicell also is verrucose), about 9 verrucae
visible along each process, becoming more crowded and
simpler towards the apex of the process ; lower margin
smooth ; with another series of verrucae stretching hori-
zontally from tip to tip of adjacent processes across the
face of the semicell, and a further series of granules round
its base. Vertical view 3- or 4-angled, angles produced
into short tapering processes, lateral margins concave and
verrucose, and with another curved series of verrucse
stretching from angle to angle just within each margin.
Chloroplast axile, with a central pyrenoid in each semi-
cell.

Zygospore unknown.

Length 48-57 \L ; breadth, including processes, 58-
72 \L ; breadth of isthmus 10-12[ji.

WALES. — Capel Curig, Carnarvonshire ! (Cooke &
Wills). In the plankton !

SCOTLAND. — Near Loch Dawan, Aberdeen (Roy &
Biss.). Rhiconich, Sutherland!

IRELAND. — Galway (Arch.) .

Geogr. Distribution. — Norway. Sweden. Finland.
Ceylon (var.). United States.

This is one of the most beautiful of Desmids. Its granulation

142 BRITISH DESMIDIACE^l.

is exquisite, and is one of the most constant characters of the
species. It is confined to the western part of the British Isles.

141. Staurastrum anatinum Cooke £ Wills.
(PL CXLVI, fig. 7 ; PL CXLVII, fig. 1.)

Staurastrum anatinum Cooke & Wills, Cooke in Grevillea, 1880, p. 92, 1. 139,
f. 6 ; Wills in Midland Naturalist, 1881, p. 18, t. 5, f. 3 ; Turner, Alg.
Strensall Common, 1883, f. 4 ; Wolle, Desm. U. S. 1884, p. 139, t. 51,
f. 1, 2 ; Cooke, Brit. Desm. 1887, p. 176, t. 61, f. 2 ; De Toni, Syll. Alg.
1889, p. 1221 ; West, Freshw. Alg. N. Wales. 1890, p. 280, t. 5, f. 12 ;
Roy & Biss. Scott. Desm. 1893, p. 16 ; W. & G. S. West, Alg. S. England,
1897, p. 496 ; Alg. N. Ireland, 1902, p. 54, t. 1, f. 24, 25 ; Scott. Freshw.
Plankton, I, 1903, p. 530 ; Further Contrib. Plankt. Scott. Lochs, 1905,
p. 487 ; Brit. Freslnv. Phytoplankton, 1909, p. 174 and 168 ; Borge,
Botan. Notiser, 1913, p. 50.

Cells large, about 1 \ times broader than long, including
the processes, deeply constricted, sinus acute, and
opening widely; semicells subfusiform, ventral margin
more convex than the dorsal, upper angles produced to
form fairly long stout divergent processes, provided
with several series of well-marked denticulations and
tipped with two or three strong spines ; apex of semi-
cell slightly convex, and verrucose. Vertical view tri-
angular or quadrangular, sides straight or very slightly
concave, angles produced to form processes, lateral
margins verrucose, with another series of about 6 emar-
ginate verrucae just within each margin.

Zygospore unknown.

Length, without processes, 33-46 [i ; with processes,
50-65 pi ; breadth, with processes, 80-1 13 pi; breadth
of isthmus 10-1 5 '5 pi.

ENGLAND.- -Plankton of Buttermere, Crummock Water
and Ennerdale Water, Cumberland ! Plankton of Red
Tarn, Codale and Easedale Tarns, Westmoreland ! New
Forest, Hants !

WALES. — Capel Curig ! (Cooke & Wills) and Llyn-y-
cwm-ffynon, Carnarvonshire ! In the plankton !

SCOTLAND. — Slewdrum, Blair Glas, between Loch
Kinord and Cambas, Aberdeen ; near Curran in
Strachan, Kincardine ; Glen Coe, Argyle (Roy & Biss.).

STAURASTEUM. 143

Rkiconich, Sutherland ! Common in the plankton of
Lochs nan Cuinne, Ghriama and Ruar, Sutherland ;
Loch Luichart, Ross, and Loch Bairness, Inverness !
In the plankton of 10 lochs in Lewis and Harris, Outer
Hebrides, and in the plankton of the Shetlands.

IRELAND. - -Donegal ! Gal way ! Kerry! London-
derry ! In plankton, Galway, Kerry, Lough Neagh, and
Lough Beg, Londonderry !

Geogr. Distribution.- -Norway. Sweden. Finland,
Denmark. United States.

There are apparently two distinct forms of this Desmid,
although the fact was never commented upon by Professor
West. The ordinary form, figured by Cooke, is the larger
of the two (cf. PL CXLVI, fig. 7). It has a broadly fusiform
' body," and short, stout diverging processes, tipped with
2 or 3 large spines. The other form (see PL CXLVII, fig. 1),
is exactly similar in shape, or sometimes the * body ' of the
semicell is more cup-shaped, but it is much smaller, and some-
times the processes are relatively longer. The granulation of
the cell differs from that of the larger form, in that there is only
one row of verrucse across the top of the semicell ; in the vertical
view the marginal series of verruca is wanting, onlv the row

c? o ' «/

within the margin being present. This form was recorded by
Professor West from the plankton of Loch Cuthaig (W. & G. S.
West, 'Further Contrib. Plankton Scottish Lochs,' 1905, p. 487),
without any reference being made to its differing slightly from
the form figured by Cooke & Wills. Professor West's drawing
of this Desmid from the above Scottish locality is reproduced on
PL CXLVII, fig. 1. The writer has also observed this smaller
form in material from the lower lake at Capel Curig. These
specimens occurred in great abundance along with the larger
and typical form. The small forms from Capel Curig are more
like the large typical form than the small specimens from
Loch Cuthaig, but in both cases the cells are constantly
smaller, and the marginal series of verrucae is wanting in the
vertical view. Furthermore there is always a difference in the
chloroplasts of the two forms. The larger one has an axile
chloroplast with a pyrenoid in each angle of the semicell, i. e.
typically 3 pyrenoids in the ordinary triangular specimen (see
Carter, 'Chloroplasts of Desmids,' IV, 1920, t, xiv, f. 19, 20).
The smaller form, however, has only a central pyrenoid in each

144 BRITISH DESMIDIACE^E.

semicell. There is a strong resemblance between the small form
and var. longibrachiatum West (see PL CXLVII, fig. 5), and yet
it is strange that the two were not considered identical by the
Wests, who listed PL CXLVII, fig. 1 as typical St. anatinum.

St. anatinum is a very handsome Desmid, which, although
widely distributed in the British Isles, is only really abundant
in North Wales, the west of Ireland, and the north-west of
Scotland. Thus it is more frequently found in bogs and in the
plankton of lakes lying on the older palaeozoic rocks, although it
is not exclusively confined to such localities. This fact rather
•explains its occurrence in Norway and Sweden (where the
geological formation is similar to that of the western parts of
the British Isles), although it has not yet been recorded for the
greater part of continental Europe. It is one of the most
characteristic Desmids of Welsh, Scotch and Irish plankton.

Var. grande W. & Cl. S. West. (PL CXLVII, fig. 6.)

St. anatinum var. grande West & G. S. West, Alg. N. Ireland, 1902, p. 55,
t. 1, f. 27 ; Scott. Freshw. Plankton, I, 1903, p. 530 ; Further Contrib.
Plankt. Scott. Lochs, 1905, p. 504.

Cells larger than in the type, with, the processes
slightly longer.

Length, without processes, 66 \i ; with processes,
105-112 [i ; breadth, with processes, 140-148 p ; breadth
of isthmus 15'5 \L.

WALES.- -In the plankton.

SCOTLAND.- -Rhiconich and in the plankton of Loch
Shin, Sutherland ! Plankton of L. Shiel, Inverness ;
of Loch Doon, Ayr ; of Loch Fadaghoda and 5 other
lochs in Lewis and Harris, Outer Hebrides !

IRELAND. — Lough Anna, Donegal !

This variety is one of the most handsome of all Staumstm.
It is more abundant in plankton than in any other situation.

Var. Lagerheimii (Schmidle) W. & G. S. West. (PL

CXLVII, fig. 4.)

St. Lagerheimii Schmidle, Lappmark Siisswasseralgen, 1898, p. 03, t. 3, f. 10.
St. Landmarkii Huitfeldt-Kaas, Plankton Norske Vande, 1906, p. 155, t. 2,

f. 32, 33.
St. anatinum var. Lagerheimii, West & G. S. West, Plankton Engl. Lake

Distr. 1909, p. 289.

STAURASTRUM. 145

A variety with very short processes, which are less
than half the normal length ; arrangement of verrucse
as in the type.

Length 53-65 JJL ; breadth, with processes, 72-88 a.

ENGLAND. --In the plankton of Ennerdale Water,
Cumberland ! : and Easedale Tarn. Westmoreland !

J s

Geogr. Distribution .--^OTWB,J. Finmark.

This variety, although not exclusively confined to plankton,
prefers this habitat to any other situation.

Var. biradiatum West, (PL CXLVII, fig. 2.)

N/. 'iiififlninn subsp. biradiatuni \\Vst, Al<r. W. Ireland, 1892, p. 185, t. 24,
f. 3.

Cells slightly smaller than in the type, about twice
as broad as long, including the processes, deeply con-
stricted. sinus nearly linear for part of its length, semi-
cells subfusiform, ventral margin much more convex
than the dorsal, processes not so divergent as in the
type. Vertical view fusiform, produced into processes
at the poles, lateral margins verrucose, with a series of
verruca? just within each margin.

Length 40 \L ; breadth, with processes, 82 [j. : breadth
of isthmus 8 \L ; thickness 23 ^ .

IRELAND.- -Lakes, near Recess, Galway ! Adrigole,
Cork!

Var. truncatum West. (PL CXLVI, fig. 8.)

<s7. (uirttinum var. truncafiim West, Alg. W. Ireland, 1892, p. 185, t. 24,
f. 2 ; West & G. S. West, Further Contrib. Plankt. Scott. Lochs, 1905,
p. 486.

Semicells more elliptical than in the type, ventral and
dorsal margins almost equally convex, but with the apex
distinctly flattened, processes inserted lower than in the
type, and beginning abruptly, the " body ; ' not tapering
so gently into the processes.

Length 50-65 (JL ; breadth, including processes, 75-
100 \JL ; breadth of isthmus 15-20 p.

SCOTLAND.- -Plankton of Lochs Cuthaig, Fadaghoda,

VOL. v. 10

146 BRITISH DESMIDIACE^E.

Stranabhat and an Tomain, Lewis, Lochs Diracleet and
Laxadale, Harris, Outer Hebrides !

IRELAND.- -Lough Guitane, and in the plankton,
Kerry ! Plankton of Lough Neagh !

St. anatinum var. truncatum is more frequent in plankton
than in any other hahitat.

Var. pelagicum W. & G. S. West. (PL CXLVII, fig. 3.)

St. anatinum var. pelagicum West & G. S. W^est, Alg. N. Ireland, 1902,
p. 55, t. 1, f. 26 ; Scott. Freshw. Plankton, I, 1903, p. 530 ; Further
Contrib. Plankton Scott. Lochs, 1905, p. 487.

Cells smaller than in the type, semicells relatively
longer (excluding the processes) and more cup-shaped ;
processes slightly narrower.

Length, without processes, 40-46 \L ; with processes,
57-65 \L ; breadth, with processes, 65-77 \L ; breadth of
isthmus 11*5-1 2' 5 [L.

SCOTLAND. — Plankton of Loch Shin, Sutherland ! ; of
Lochs na Criche and Shiel, Inverness ! ; and of Loch Mor
Bharabhais, Lewis, Outer Hebrides !

IRELAND.- -Plankton of Lough Beg, Londonderry !

This variety occurs exclusively in plankton, and is readily
distinguished from the type by its smaller size, by the different
shape of the semicells, and by the narrower and more delicate
processes. The granulation is similar to that of the type.

Var. longibrachiatum W. & G. S. West. (PI. CXLVII,

fig. 5.)

St. anatinum var. longibrachiatum West & G. S. West, Further Contrib.
Freshw. Plankton Scott. Lochs, 1905, p. 504, t. 7, f. 8, 9.

Body of semicell practically smooth beneath the apical
row of verrucae ; processes much longer than in the
type, tapering gradually to the apices. Lateral margins
in end view undulate but not verrucose, with a series
of verrucse just within the margin as in the type.

Length, without processes, 37 ^ ; breadth, without
processes, about 29^; with processes, 110-131 (Ji ;
breadth of isthmus 11*5 i.

STAURASTRUM. 147

SCOTLAND.- -Plankton of Loch Langabhat, Lewis,
Outer Hebrides !

142. Staurastrum sexcostatum Breb.
(PL CL, fig. 14.)

Staurastrum sexcostatum Breb. in Menegh. Synops. Desm. 1840, p. 228 ;
Ralfs, Brit, Desm. 1848, p. 129, t. 23, f. 5; Arch, in Pritch. Infus. 1861,
p. 744 ; Rabenh. Flor. Europ. Alg. 1868, p. 216 ; Xordst. Desm. Arctose,
1875, p. 36 ; Kirchn. Alg. Schles. 1878, p. 165 ; Racib. Xoim. Desm. Polon.
1885, p. 29 ; Cooke, Brit. Desm. 1887, p. 180, t. 64, f. 1 ; De Toni, Syll.
Alg. 1889, p. 1232 ; West, Alg. X. Wales, 1890, p. 20 ; Alg. Engl. Lake
Distr. 1892, p. 21 ; Roy & Biss. Scott. Desm. 1893, p. 25 ; Borge, Siissw.
C'hlor. Archang. 1894, p. 39 ; West & G. S. West, Alg. S. England, 1897,
p. 496 ; G. S. West, Variation Desm. 1899, p. 406 ; Comere, Desm. de
France, 1901, p. 153, t. 10, f. 16 ; Borer. Alg. Faeroes, 1901, p. 234 ;
West & G. S. West, Alga-fl. Yorks. 1902, p. 108.

St. Jenneri Ralfs, in Ann. Mag. Xat. Hist. vol. 15, 1845, p. 158, t. 11, f. 8.

Stephanoxanthium sexcostatum Kiitz. Spec. Alg. 1849, p. 184.

Didymidium (Staurastrum) sexcostatum Reinsch, Alg. Frank. 1867, p. 166.

Staurastrum (Pleurenterium) sexcostatum Lund. Desm. Suec. 1871, p. 74.

Pleurenterium (Staurastrum) sexcostatum Xordst. Xorges Desm. 1873, p. 37.

Cells of medium size, about ly-2 times longer than
broad, deeply constricted, sinus triangular with a minute
excavation at its apex ; semicells broadly elliptical, or,
including the processes, somewhat compressed hexa-
gonal in form, lateral angles very slightly produced,
truncate, with a circle of minute acute granules round
their apex ; both dorsal and ventral margins of lateral
angles granulate, with about 3 or 4 granules along each,
those near the apex of the semicell becoming emarginate ;
apex of semicell truncate, irregularly granulate or smooth
(according to the aspect) ; angles with about 2 concen-
tric series of denticulations ; base of semicell also with
a circle of prominent granules. Vertical view usually
hexagonal, sides concave, angles truncate, scarcely
produced, tipped with tiny granules, and with a second
series of denticulations ; lateral margins smooth, apex
with curved series of granules, often emarginate, extend-
ing from angle to angle just within the margins.

Zygospore unknown.

Length 40-65 JJL ; breadth, including processes, 34-
47 '5 pi ; breadth of isthmus 14-25 pi.

ENGLAXD. — Brother's Water, Westmoreland ! Den-

148 BRITISH DESMIDIACE^:.

holme, W. Yorks ! Mickle and Cronkley Fells, N. Yorks !
Warwicks (Wills). Gloucester (Ealfs}. Esher West End
Common, Surrey ! Sussex (Ealfs}. Dartmoor, Devon
(Hams). Cornwall (Marquand).

WALES. — Snowdon, Llyn Padarn, and Y Foel Fras,
Carnarvonshire ! Dolgelly, Merioneth (Ralfs).

SCOTLAND. — Sutherland, Aberdeen. Kincardine, Forfar,
and Perth ! (Roy & Biss.). Near House of Hill, Wigtown !

IRELAND. --Lough Anure, Donegal ! Mayo and Clare-
Isle ! Lough Guitane, Kerry ! Adrigole, Cork !

Geogr. Distribution. --Fiance. Germany. Galicia in
Austria. Portugal. Norway. Sweden. Poland (var.).

Cj *J

N. Russia. Faeroes. Spitzbergen. Greenland.
Var. productum West. (PL CL, fig. 15.)

? St. tuberciththim Benn. Alg. Engl. Lake Distr. 1886, p. 12, t, 2, f. 24.

St. ctcuhatum var. ornatitm f. simplex Boldt, Desm. Gron. 1888, p. 38?
t, 2, f. 49.

St. sexcostaturn subsp. production West, Alg. Engl. Lake Distr. 1892, p. 21,.
f. 34 ; Alg. S. England, 1897, p. 496 ; 8chmidle, Alg. Geb. Oberrheins,
1893, p. 552 ; Bohlin, Flor. Algol, d'eau douce d'A^-ores, 1901, p. 62,
t. 1, f. 24 ; West & G. S. West, Alga-fl. Yorks. 1902, p. 108 ; Borge,
Botan. Notiser, 1913, p. 51.

Cells relatively broader than in the type, about as long
as broad, including the processes ; processes short and
truncate (longer, however, than in the type), with a
circle of about 6 acute granules at their tip ; base of
semicell with a circle of acute granules ; vertical view
6-radiate, arrangement of granules essentially similar to
that of the type, but cell- wall very much more verrucose,
granules tending to become scattered.

Length 40-43 (JL ; breadth 43 [i ; breadth of isthmus.
16-17 [L.

ENGLAND. Borrowdale, Cumberland ! Bowness,
Brother's Water and Helvellyn (at 2400 feet), Westmore-
land ! Cocket Moss near Giggleswick, and bog 2 miles
south of Clapham, W. Yorks ! Cronkley Fell ; bog near
Widdale Beck, and Pilmoor, N. Yorks ! Bog near Long-
moor Pool, Sutton Park, Warwickshire ! New Forest,,
Hants ! Near the Lizard, Cornwall !

WALES. — Moel Siabod, Carnarvonshire !

STAURASTRUM. 149

SCOTLAND. — Sutherland, Ross, Aberdeen, Kincardine,
Forfar !, Perth !, Dumbarton, Argyle and Renfrew (Roy
& Biss.). Xorth of Fort Augustus, Inverness !

IRELAND. — Carrantuohill, Kerry ! Slieve Donard,
Down (at 2000 feet) !

Geogr. Distribution. — Germany. Sweden. C4reenland.
Azores.

This variety differs from the type chiefly in its broader semi-
cells and rather longer processes, and in the greater development
of the verruca.

f

143. Staurastrum natator West.
(PL CXLVII, fig. 7.)

Staurastrum natator West, Aljr. W. Ireland, 1892, p. 183, t. 23, f. 14 ; West
& G. S. West, Brit. Fresh\\ . I'liyt<. plankton, 11*09, p. 202.

Cells of medium size, about twice as long as broad,
excluding the processes, constriction fairly deep, sinus
small, acute, semicells subquadrangular, broadening
slightly upwards, lateral margins slightly crenate, apex
with three large mucronate or emarginate verrucse,
upper angles produced to form long diverging processes,
tipped with 3 minute spines and with many series of
denticulations, centre of each face with a rounded pro-
tuberance ornamented with about 7 or 8 granules
arranged in a circle. Vertical view rounded or rhom-
boidal, elongated at the poles to form long processes, with
a prominent subtruncate protuberance in the middle of
each lateral margin, and 2 series of 3 verrucae on the
apex. Semicells in side view rounded, with a protuber-
ance on each side, and a process projecting vertically
between two apical verrucao.

Zygospore unknown.

Length, without processes, 34-38*5 \L ; with processes,
53-67 pi ; breadth at base of semicell 15-20 pi ; at apex,
excluding the processes, 20-25 pi ; breadth, including
processes, 57-75 pi ; length of processes 20-32'5 pi ;
breadth of isthmus 8-1 2 '5 pi ; thickness 19-2 1*5 pi.

SCOTLAND.- -Rhiconich, Sutherland !

150 BRITISH DESMIDIACBJE.

IRELAND.- -Derryclare Lough, and in lakes, Clifden
to Roundstone, Galway ! Near Castlebar, Mayo.

Geogr. Distribution. — Scandinavia. Finland (form).
United States (var.).

This rare and beautiful Desmid is only found in bogs in the
region of the older palaeozoic rocks. It is not closely allied to
any other British species, but is similar in some respects to St.
brachioprominens~Boig. ('Desm. Brasil,5 1890, p. 952, t. 5, f. 22).
Sometimes it is further ornamented with 2 rings of granules near
the base of the semicell. Gronblad (' Desm. Keuru ' 1920. p. 70,
t. 3, f. 109, 110) records a trigonal form of this species, which,
however, seems to differ in other ways from the form originally
described.

144. Staurastrum irregulare West.
(PL CXLIX, fig. 7.)

Staurastrum irregulare West, New Brit. Freshw. Alg. 1894, p. 12, t. 2, f. 49T
50 ; Johns. New Rare Desm. U. S. I, 1894, p. 288. t. 211, f. 10 ; West &
G. S. West, Desm. U. S. 1898, p. 314 ; Bohlin, Flor. Algol, d'eau douce
d'A?ores, 1901, p. 56, f. 14 ; Gutw. Alg. Ins. Java, 1902, p. 600, t. 40,
f. 64.

Cells small, slightly longer than broad, constriction
fairly deep, with a minute median incision ; semicells
inversely trapeziform, apex smooth and slightly concave,
upper angles produced to form short diverging processes,
with denticulate nodulose margins, and bidenticulate
apices ; vertical view biradiate, very slightly swollen
in the middle, with a truncate and scrobiculate process
on each side ; side view of cell fusiform with a deep con-
striction, and a scrobiculate process on each side near
the base of the semicell. Cells often twisted so as to
present a very irregular and distorted appearance.

Zygospore unknown.

Length, without processes, 9 '4-9 '6 [JL : with processes,
15'3-18'2fjL ; breadth, including processes, 13'5-17'3[JL ;
breadth of isthmus 4'8-5'7 [i : thickness 6'6-7'7[i.

ENGLAND.- -Plankton of Brother's Water. Westmore-
land ! Pilmoor, N. Yorks !

SCOTLAND. --Rhiconich, Sutherland! Glen Nevis, In-
verness !

STAURASTRUM. 151

IRELAND.- -Lough Gartan and near Lough Magrath,
Donegal ! Ballvnahinch, Galway !

Geogr. Distribution. — Scandinavia. Java (var.). Azores.
United States.

»

This characteristic little species is closely allied to St. tetracerum
Ealfs, from which it is readily distinguished by the protuberance
in the centre of each face of the semicell.

145. Staurastrum Arachne Ealfs.
(PI. CL, fig. 1.)

Arachne Kali's, in Ann. Mag. Xat. Hist. vol. 15, 1845, p. 157,
t. 11, f. 6; Brit. Desm. 1848, p. 13(3, t. 23, f. 6; Arch, in Pritck. Inf.
1801, p. 744 ; Pxabenh. Krypt.-ti. Sachs. 18(53, p. 191 ; Flor. Europ. Alg.
18(58, p. 210; Lund. Desm. Suec. 1871, p. (59 ; Kirchn. Alg. Schles.
1878. p. 168 ; Turn. Alg. Strensall Common, 1883, f. 20 ; Wolle, Desm.
U. S.' 1884, p. 129, t. 42, f. 38-42 ; Bpldt, Sibir. Chloroph. 1885, p. 118 ;
Cooke, Brit. Desm. 1887, p. 182, t. 63, f. 4 ; Xordst. Desm. Bornholm,
1888, p. 206 ; De Toni, Syll. Alg. 1889, p. 1229 ; West, Alg. W. Ireland,
1892, p. 187 ; Roy & Biss". Scott. Desm. 1893, p. 1(5 ; West & G. S. West,
Desm. U. S. 1898, p. 316 ; Cushmau in Pvhodora, v. 7, 1905, p. 201 ;
West & G. S. West, Brit. Kreshw. Phytoplankton, 1909, p. 203.

Goniocystis (Pentasterias) Ara<-hne Mass. Brit. Alg. 1845, p. 355, t. 85, f. 8.

Phycastnim Arachne Kiitz. Spec. Alg. 1849, p. 181.

Ph. (Stenactinium) AracJnn Xa!_f. <Jatt. «-inz. Alg. 1849, p. 128.

Cells small, about twice as broad as long, including
the processes, deeply constricted, sinus acute ; semicells
cup-shaped, ventral margin strongly ventricose. dorsal
margin nearly straight or slightly convex, upper angles
produced to form long slender processes, nearly as long
as the cell itself, each process tipped with about 3 minute
spines, and rough with numerous concentric series of
granules. Vertical view usually 5-angular, angles pro-
duced to form long processes, sides concave, sometimes
with a few scattered granules just within each lateral
margin between the processes.

Zygospore unknown.

Length 26 \L ; breadth, without processes, about 16 \i ;
with processes, 40-55 [JL ; length of processes 14-18 \L ;
breadth of isthmus 8-9 \i .

ENGLAND. — Strensall Common, N. Yorks (W. B.
Turner). Thursley Common, Surrey ! New Forest,
Hants !

152 BRITISH DESMIDIACE^E.

WALES.- -Llyn-y-cwm-ifynon ! and Capel Curig ! (Cooke
<& Witts), Carnarvonshire. Dolgelly (Ralfs), Merioneth.
In the plankton

SCOTLAND.- -From several localities in Aberdeen ;
Nigg, Craithes, and Cuiran, Kincardine ; Glen Coe,
Argyle (Roy & Biss.). Rhiconich, Sutherland ! Loch
Bairness, Inverness ! Lochs Fadaghoda and Stranabhat,
Lewis, Outer Hebrides ! In the plankton !

IRELAND. --Dungloe, Donegal! Derrvclare Lough,
Athrey Lough, Ballynahinch, and in Lakes, Clifden to
Roundstone, Galway ! Adrigole, Co. Cork ! In the
plankton !

Geogr. Distribution.- -Fiance. Germany. Galicia and
Austria. Italy. Norway. Sweden. Finland. Denmark.
Bornholm. Faeroes. Greenland. Japan. Australia.
Central Africa, United States.

St. Arachne is a most characteristic species easily recognised
by its long slender processes, which, when the individual is in an
oblique position, give the appearance of a spider with long
untidy legs. It is not at all general in its distribution, but
sometimes occurs in profusion in the western areas of the British
Isles, having a decided preference for the older palaeozoic and
precambrian formations.

Var. curvatum W. & G. S. West, (PL CL, fig. 2.)

St, Arachne var. curt-alum West & G. 8. West, Scott. Freshw. Plankt. I,
1903, p. 549, t, 18, f. 9 ; Further Contrib. Plankton Scott. Lochs, 1905,
p. 487, t. 1, No. 2, f. 5.

Processes bent slightly, but distinctly upwards ; in
end view 4- or 5 -radiate.

Length 30 pi ; breadth, without processes, 18 pi ; with
processes, 57-70 [x ; breadth of isthmus 9 pi.

SCOTLAND.- -Plankton of Lochs nan Cuinne and Ruar,
Sutherland !

This variety is either 4- or 5-radiate, and differs from all other
forms of St. Arachne in the outwardly curved processes.

Var. arachnoides W. & G. S. West. (PL CL, fig. 3.)

St. arachnoides West, Alg. W. Ireland, 1892, p. 180, t, 24, f. 4.

St. Arachne var. arachnoides West & G. S. West, Alg. N. Ireland, 1902, p. 56.

STAURASTRUM. 1 53

Differs from the type in the possession of an apical
ring of about 9 or 10 verrucae. which are visible as
emarginate granules across the apex in the front view.

Length 37 JJL ; breadth, without processes, 15-20 y. ;
breadth, including processes, 55-71 tj. : length of pro-
cesses 20-27 [JL ; breadth of isthmus 9 JJL.

IRELAND.- -Lough Alachugh, Donegal ! In lakes, Clif-

vden to Roundstone, Ualwav !

</

146. Staurastrum Ophiura Lund.
(PL CLII, figs. 1. 2.)

Staurastrum <J/i/iii/r<i Lund. Desin. Suoc. 1^71. p. ti'.i. t. 4. t. 7: Xordst.
Norgea l)»->m. IS73, p. 3.1 : \V«.II«>, Dosm. I". S. lss4. p. 134. t. 43, f. 10,
11 : Cookp, Brit. Desni. 1SS7, p. 172 (<h^<-r. only): DC T.uii. Syll. Alg.
INS!*, p. 1212; \\Vst \- (J. S. \\Vst. Some X. Am.-r. D.-sm. 1896, p. 208,
t. IS. f. Hi; Sc,,tt. Fivshw. Plankton. I. 1!M>3. p. .").".(>: Notes Alj;. Ill,
!'.»>3. ]). II: Further Contril*. Fn-sh\v. Plankton Scott. Lochs, p.-nr,,
p. 4s7: Phytoplankt. KiiL'l. Lake Di^tr. I'.MIJI. p. 2'.ni: Horiie, Botan.
Xotiscr, 1!H3. ].. 32.

Cells large, about twice as long as broad, not including
the processes, constriction slight ; semicells cuneate,
broadening upwards ; apex slightly convex, upper angles
produced to form long .slender processes, parallel, or
very slightly converging with undulate and denticulate
margins, upper margin rougher than the lower ; semi-
cell with a ring of papillae at its base, of which about
7 are visible, and with a circle of large conical granules
or flattened verruca? on its apex. Vertical view 4-9-
radiate (in British specimens usually 6-9), processes
very long and gradually tapering to their apices, which
are provided with about 3 minute spines, and writh
numerous series of denticulations which become larger
towards the base of the process ; apex with a circle of
large conical nodules or flattened verruca, which usually
alternate with the processes. Chloroplast axile, with a
central pyrenoid, and a number of ridges.

Zygospore unknown.

Length 65-91 u. ; breadth, without processes, 34-46 (JL ;
including processes, 128-1 69 pi; breadth of isthmus
19-5-26 L.

154 BRITISH DESMIDIACEJE.

ENGLAND.- -Near Ambleside (Archer) and plankton
of Easedale Tarn !, Westmoreland.

WALES. — Llyn Ogwen, Carnarvonshire !

SCOTLAND.- -Plankton of Lochs Shin, Ghriama, nan
Cuinne, and a Gharbh Bhaid Mhoir, Sutherland ! ; of
Loch Shiel, Inverness ! : of Loch Tay, Perth ! ; of Lochs-
Cuthaig, Fadaghoda, Stranabhat, an Sgath, and an
Tomain, Lewis, and Lochs Diracleet and Laxadale,
Harris, Outer Hebrides ! In bogs, Sutherland and Outer
Hebrides !

IRELAND. — Connaught (Adams).

Geogr. Distribution.- -Norway. Sweden. Finland.
LTnited States.

This beautiful Desmid is a distinctly western type,* occurring
only in the region of the older and harder rocks in the western
parts of the British Islands. It is a general, but not abundant
constituent of Scottish plankton, and is also frequently found in
permanent Sphagnum bogs. The apical verrucae are subject to
considerable variation, being sometimes large smooth conical
nodules, and sometimes irregular lobed warts.

Var. cambricum W. & C4. S. West. (PL CLII, figs. 3, 4.)

St. Ophiura Cooke in Grevillea, 1880, t. 140, f. a-c : Brit. Desm. 1887, t. 59,
f. 1 (not descr. on p. 172) ; West, Alg. N. Wales, 1890, p. 18, f. 15.

St. Ophiura var. cambricum West & G. S. West, New Brit. Freshw. Alg.
1894, p. 12.

Cells about ll times broader than long, including the
processes, which are relatively shorter than in the type ;
apex of semicell more convex, with a circle of conical
nodules.

Length 75-80 [i ; breadth, including processes, 98-
110[ji ; breadth of isthmus 16-18'5[JL.

WALES. — Capel Curig ! (Cooke <£ Witts) and in the
plankton, Carnarvonshire !

This variety differs from the type chiefly in its relatively
shorter processes. The conical nodules of the apex are found
occasionally also in the typical form instead of flattened verrucse,
and cannot be considered characteristic of var. cambricum.

* See p. 18.

STAURASTRUM. 155

147. Staurastrum verticillatum Arch.
(PL CLI, figs. 7, 8.)

Staurastrum verticillatum Arch, in Quart. Journ. Micr. 8ci. vol. 9, I860,
p. 196 : Cooke, Brit. Desm. 1887. p. 177, t. 61, f. 3 ; De Toni, 8yll. Alg.
1889, p. 1223 : West & G. S. West. Scott. Freslnv. Plankton, I, 1903,
p. 549, t. 14. f. 7.

Cells large, nearly 3 times longer than broad, excluding
the processes, constriction slight, sinus acute ; semi-
cells almost cylindrical, slightly broader at the apex,
which is convex and almost smooth ; upper angles
produced to form long, strongly divergent processes
tipped with 2 or 3 minute teeth, and with many series
of denticiilations, the upper margin of the process con-
siderably rougher than the lower ; semicells with a ring
of papillae at the base, about 7 of which are visible in the
front view. Vertical view 8-10-radiate. processes very
long and tapering gradually, with denticiilations stronger
towards the base of the process, apex of semicell with a
pair of large verrucse near the base of each process.

Zygospore unknown.

Length, without processes, 76-79 u : with processes,
136-1 43 [JL ; breadth, without processes, about 26-28 ku. ;
with processes, 124-1 30 y. ; breadth of isthmus 20 pt.
[Note.- -The breadth without processes given by W. &
G. S. W., 'Scott. Fresliw. Plankt,' I, 1903. p/549, as
36-38 [JL is erroneous.]

SCOTLAND.- -Rhiconich. Sutherland ! Plankton of
Loch Mor Bharabhais, Lewis, Outer Hebrides !

IRELAND.- -Near Maam, Galway (Arch.).

Geogr. Distribution.- -France. Norway.

The front view of this species is so characteristic that it can
readily be distinguished from both St. Ophiura Lund, and St.
Archerii West. Its processes are more slender and more diver-
gent than those of the latter species.

148. Staurastrum Archerii West.
(PL CLIIL figs. 6, 7.)

Staurastrum Archerii West, Alg. W. Ireland, 1892, p. 183, t. 23, f. 15.

Cells large, about twice as long as broad, excluding

156 BRITISH DESMIDIACE^E.

the processes, constricted at the middle, sinus short and
obtuse ; semicells broadly cuneate, or cup-shaped, apex
smooth and convex ; lateral margins nearly straight,
upper angles produced to form very long slender pro-
cesses, gently curved obliquely upwards, tipped with
3 small spines, and with many transverse series of den-
ticulations. Vertical view 9- or 10-radiate, apex smooth.

Zygospore unknown.

Length, without processes, 69-78 ^ ; with processes,
90-1 20 (Jt ; breadth, without processes, 43-48 y. ; with
processes, 130-140 (i ; greatest length of processes, 50 n ;
breadth of isthmus 24-26 [i.

IRELAND. — Bally nahinch and Derryclare Lough, Gal-
way !

This species is readily distinguished from St. Opkiitra Lund,
by its smooth apex, and slightly diverging processes. From
St. verticittatum Arch, it is distinguished by the different form of
the semicells.

149. Staurastrum elongatum Barker.
(PL CLI, figs. 2-5.)

Staurastrum elongatum Barker, in Quart. Journ. Micr. Sci. vol. 9, 1869,
p. 424; Wolle, Desm. U.S. 1884, p. 130. t, 40, f. 11, 12; Cooke, Brit.
Desm. 1887, p. 172, t. 59. f . 2 ; De Toni, Syll. Alg. 1889, p. 1212 ; Roy
& Biss. Scott. Desm. 1893, p. 19 ; West & G. S. West, Desm. U. S. 1898,
p. 317 ; G. S. West, Brit, Freshw. Alg. 1904, p. 172, f. (55 E ; West &
G. S. West, Brit, Freshw. Phytoplankton, 1909, p. 202.

St. terebrans Nordst. Norges Desm. 1873, p. 34, t. 1, f. 16.

Cells large, about 6 times longer than broad, excluding
the processes, constriction slight, sinus acute and open ;
semicells elongated cvathiform, considerablv swollen at

«/ «/

the base, where there are 3 or 4 close decussating rows
of granules ; apex convex, somewhat truncate in the
middle, with 2 emarginate verruca?, and two others just
beneath ; sides concave ; upper angles produced to
form short stout processes, parallel or very slightly
divergent, tipped with 3 minute spines, and with 2 or
3 series of acute denticulations. Vertical view triangular,
sides concave with 2 median emarginate verrucse, and

STAURASTRUM. 157

2 others just within the margin ; angles produced to
form short processes.

Zygospore unknown.

Length. 60-77 ^ ; breadth, including processes, 42-
48 [JL ; breadth at base of semicell 14-15 (j. ; breadth of
isthmus 9 \JL .

SCOTLAND.- -£oole we, Ross; Glen Coe. Argyle (Roy
& Biss.). Ehiconich, Sutherland !

IRELAND.— Kvlemore. Galwav, and Glengariff, Cork

»/ ^ ~ ~

(Arch.).

Geogr. Distribution. --Sow-ay. Sweden. United States.

This characteristic species cannot be confused with any other,
the form and proportions of its cells being most striking. It is
extremely localized in its distribution, and is only known from
one or two localities in the western areas of the British Isles.

150. Staurastrum barbaricum W. & G. S. West.

(PL CLI, fig. 6.)

^/<tur(ts/ru)/i l><irli<iri<-/int West & (> . S. West, Alg. N. Ireland, 1902, p. 53,
t. 1, f. 23.

Cells small. Ij times broader than long, including the
processes, deeply constricted, sinus open ; semicells
elliptic-obsemicircular, lower margins biundulate, apex
convex and undulate, angles produced to form very
short slightly diverging processes, with 3 tiny spines at
their apex, and 2 series of denticulations ; vertical view
triangular, sides concave, angles deeply cleft, each
forming two short slightly diverging processes.

Zygospore unknown.

Length 30 \L ; breadth, including the processes, 38-
41 [i ; breadth of isthmus 8 \L.

IRELAND. — Bog near Lough Xeagh, Londonderry !

This remarkable Staurastrum stands alone in the possession
of two denticulate processes at each angle, arranged in a hori-
zontal plane. These processes, which are terminated by 3 small
teeth, each possess 2 rings of denticulations. and are disposed in
precisely the same manner as the smooth processes of St. Iceve
Ealfs, and St. fissum Turn.

158 BRITISH DESMIDIACE^;.

151. Staurastrum vestitum Kalfs.
(PI. CLI, figs. 9-11 ; PI. CLII, figs. 5, 6.)

Staurastrum vestitum Ralfs, Brit. Desm. 1848, p. 142. t. 23, f. 1 ; Arch, in

Pritch. Inf. 1861, p. 742 ; Rabenh. Krypt.-fl. Sachs. 1863, p. 193 ; Flor.

Europ. Alg. 1868, p. 218 (in part) ; Jacobs. Desm. Danem. 1875, p. 207 ;

Delp. Spec. Desm. subalp. 1877, p. 159, t. 12, f. 46-49 ; Kirchn. Alg.

Schles. 1878, p. 167 ; Wolle, Desm. U. S. 1884, p. 138, t. 45, f. 28-30 ;

Cooke, Brit. Desm. 1887, p. 175, t. 60, f. 3 ; De Toni, Syll. Alg. 1889,

p. 1218 ; West, Alg. Engl. Lakes. 1892, p. 20 ; Roy & Biss. Scott. Desm.

1893, p. 26 ; West & G. S. WTest, Alg. S. England, 1897, p. 496 ; Schmidle,

Lappmark Siisswasseralgen, 1898, p. 63 ; G. S. West, Variation Desm.

1899, pp. 374, 395; West & G. S. West, Alga-fl. Yorks. 1902, p. 106;

Alg. N. Ireland, 1902, p. 54.

Didymidium (Staurastrum) vestitum Reinsch, Alg. Frank. 1867, p. 167.
Staurastrum vestitum var. ornatum Istv. Diag. praev. Alg. nov. Hung.

1887, p. 240.

Cells of medium size, about 1^-2 times broader than
long, deeply constricted, sinus open ; semicells sub fusi-
form, lower margin ventricose, apex slightly convex with
about 6 emarginate granules, and two prominent emar-
ginate or bifurcate spines just under the apex ; angles
gradually produced to form fairly long processes,
usually nearly horizontal or slightly converging, tipped
with 3 strong spines and provided with several concen-
tric series of denticulations. Vertical view triangular,
angles produced into denticulate processes, lateral mar-
gins concave, with two prominent bifurcate spines
projecting from the middle of each, and sometimes with
smaller emarginate verrucse on each side ; with a dorsal
series of emarginate granules just within each lateral
margin.

Zygospore globose, with numerous spines bifurcate
at the apex (Wolle).

Length 28-43 (JL ; breadth, including - processes, 46-
90 pi ; breadth of isthmus, about 9 \i.

ENGLAND. — Near Bowness ! (Bissett), Deep Vale,
Loughrigg, and in the plankton of Easedale Tarn, West-
moreland ! Biccall Common, E. Yorks ! Hawkshead,
Lancashire ! Thursley Common, Surrey ! Near Pul-
borough, Sussex (Ralfs). New Forest, Hants ! Dart-
moor, Devon (Harris), St. Just, Cornwall !

WALES. — Capel Curig ! (Cooke & Wills) and Llyn-

STAURASTRUM. 159

y-cwm-ffynon, Carnarvonshire ! Dolgelly, Merioneth
(Rolfs}. In the plankton !

SCOTLAND.- -Ross, Inverness, Aberdeen, Kincardine
and Perth (Roy & Biss.}.

IRELAND.- -Donegal ! Mayo ! Galway ! Kerry ! Dub-
lin and Wicklow (Arch.}. Down !

Geogr. Distribution- -France. Belgium. Germany.
Switzerland. Galicia in Austria. Hungary. Italy. Nor-
way. Sweden. Denmark. Bornholm. Finland. Poland.
S. Russia. Japan. Australia. Azores. United States.
N. W. Canada. Brazil.

Few species exhibit so much variation as St. vestitum whilst
retaining at the same time their distinctive features. The main
diagnostic character of the species is the possession of the pair
of furcate spines in the middle of the lateral margins of the
vertical view. These spines themselves are subject to much
variation, being sometimes simple aculei, at other times furcate
to their base, or more rarely, doubly furcate. The general plan
of the arrangement of the spines and of the emarginate verrucas
is precisely like that of St. aculeatum. The angles of St. vestitum,
which possess 3 well-marked divergent spines at their apices,
are more produced than those of St. aculeatum, and as a rule, the
two median spines of the dorsal series become converted into
emarginate warts. Of the lateral series of spines, which are
such a marked feature of St. aculeatum. either the two median
spines only remain in St. vestitum, or they are much more
prominent than the rest. These are the characteristic furcate
spines mentioned above. Xo matter how variable the lateral
series of spines may be (including the furcate ones), those of the
dorsal series are always disposed on the same plan. The front view
of typical St. vestitum resembles very closely that of some forms
of St. aculeatum, but in the majority of specimens of the former
species, the angles are produced into processes of varying length.
In some of these the processes are very long, making the total
width of the cell as much as 90 /n ; and in others they are very
short, so that a breadth of about 46 /LI only is attained. Archer
has reported the occurrence of a biradiate form of St. vestitum.

Var. subanatinum W. & G. S. West. (PL CLIII, fig. 5.)

St. vestitum var. subanatinum West & G. 8. West, Alg. N. Ireland, 1902,
p. 54, t. 1, f. 28.

1GO BRITISH DESMIDIACE^E.

A variety with long and slightly diverging processes,
and the arrangement of the verrucse very similar to that
of St. anatinum.

Length, without processes. 35 p ; breadth, including
processes. 86-1 02 p ; breadth of isthmus 13'5fju

IRELAND. --Near Glenties, Donegal! Arderry Lough,
Galway !

In the front view this variety bears a striking resemblance to
St. anatinum, but in the end view it has the characteristic bifur-
cate spines of St. vestitum:

Var. semivestitum West. (PL CLII, figs. 7, 8.)

St. vestitum var. semicestitnm West, Alg. Engl. Lake Distr. 1892, p. 20, f. 38 ;
West & G. 8. West, Alg. 8. England, 1897, p. 496.

Cells smaller than in the type : apex of semicell nearly
straight ; in vertical view triangular, processes bent
round all in one direction as in St. cyrtocemm, with one
furcate spine at the base of the convex side of each
process.

Length, including spines, 20-28 \L ; breadth, including
processes, 34-42*5 (JL ; breadth of isthmus 4-8 \L.

ENGLAND.- -Loughrigg and Brandreth, Westmoreland !
Puttenham Common, Surrey ! Gunwen Moor, Corn-
wall !

In this small variety the spines are very much reduced. The
whole of the dorsal series is usually absent, and frequently the
whole of the lateral series as well, with the exception of one
bifurcate spine on the lateral margin. Some forms closely
resemble St. controversum, but the processes are longer and quite
straight.

152. Staurastrum aculeatum (Ehrenb.) Menegh.

(PL CLIII, figs. 1-4.)

Desmidium aculeatum Ehrenb. Inf. 1838, p. 142, t. 10, f. 12.

Staurastrum aculeatum Menegh. Synops. Desm. 1840, p. 226 ; Ealfs, Brit.

Desm. 1848, p. 142, t. 23, f. 2; Arch, in Pritch. Infus. 1861, p. 742 ;

Rabenh. Krypt.-fl. Sachs. 1863, p. 194 ; Lund. Desm. Suec. 1871, p. 68 ;

Jacobs. Desm. Danem. 1875, p. 207 ; Delp. Spec. Desm. subalp. 1877,

p. 63, t. 13, f. 3-5 ; Kirchn. Alg. Schles. 1878, p. 166 ; Wolle, Desm. U. S.

STAURASTRUM. 161

»'•

1884, p. 140, t. 45, f. 1-3 ; Cooke, Brit. Desm. 1887, p. 174, t. 60, f. 2 ;

Hansgirg, Prodr. Alg. Bohm. 1888, p. 215 ; De Toni, Syll. Alg. 1889,

p. 1216 ; Anders. Sverig. Chlorophy. 1890, p. 12 ; Liitkem. Desm.

Attersees, 1893, p. 568 ; Roy & Biss. Scott. Desm. 1893, p. 16 ; West &

G. 8. West, Alg. S. England, 1897, p. 496 ; Schroder, Beitr. Algen Riesen-

gebirge, 1898, p. 42 ; G. S. West, Variation Desm. 1899, p. 393, t. 11,

f. 28-32 ; Liitkem. Desm. Millstattersees, 1900, p. 76 ; Comere, Desm.

de France, 1901, p. 151, t. 11, f. 12 ; West & G. S. West, Brit. Freshw.

Phytoplankton, 1909, p. 203.
Goniocystis (Trigonocy-stis) aculeata Hass. Brit. Freshw. Alg. 1845, p. 353,

t. 84, f. 12.
Phycastrum aculeatum Kiitz. Phyc. Germ. 1845, p. 138 ; Spec. Alg. 1849,

p. 182.

Ph. (Stenactinium) aculeatum Nag. Gatt. einz, Alg. 1849, p. 128.
Didyrnidium (Staurastrum) aculeatum Reinsch, Alg. Frank. 1867, p. 176,

(in part).
Staurastrum aculeatum var. Ehrenbergii Rabenh. Flor. Europ. Alg. 1868,

p. 218.

Cells of medium size, about as long as broad, or up
to Ijr times broader than long, deeply constricted, sinus
acute and open ; semicells subelliptical or subfusiform,
dorsal and ventral margins almost equally convex,
though the ventral margin is not infrequently slightly
more convex than the dorsal ; lateral angles slightly or
not at all produced, terminating in 3 or 4 strong spines
and sometimes with one or two series of denticulations
beneath ; apex of semicell with a dorsal series of spines,
the median ones being sometimes emarginate ; semicells
also with a lateral series of spines running horizontally
from angle to angle across the face of the semicell.

O O

Vertical view triangular or quadrangular, sides nearly
straight, angles scarcely produced, tipped with 3 or 4
strong spines ; lateral margins with a row of spines, and
with a dorsal series of spines just within each lateral
margin.

Zygospore globose, furnished with long spines forked
or dichotomous at the apex (Lund.).

Length 33-50 (JL ; breadth, including spines, 48-60 ^ ;
breadth of isthmus 12-16 (j.; diam. zygosp., without
spines, 44 \i ; length of spines, 18 [JL.

ENGLAND. — Wastdale, Cumberland ! Loughrigg ! and
Bowness !, Westmoreland (Ralfs). Hawkshead, Lanca-
shire ! Strensall, N. Yorks (W. B. Turner). Thursley
Common, Surrey ! Sussex (Ralfs). New Forest, Hants !

VOL. V. 11

162 BRITISH DESMIDIACE^E.

Woodbury Common (4-radiate), Devon ! (Harris).
Withiel, Cornwall !

WALES. — Capel Curig ! (Cooke & Wills), Llyn Padarn !
and Pen-y-gwryd (Roy), Carnarvonshire. In the plank-
ton !

SCOTLAND.- -Ross, Inverness, Aberdeen, Kincardine,
Forfar and Perth (Roy & Biss.).

IRELAND. --Near Glenties and Lough Gartan, Donegal!
Clare Island, Mayo ! Ballynahinch, Galway ! Carrantuo-
hill, Kerry ! Castletown, Cork ! Dublin and Wicklow
(Arch.).

Geogr. Distribution.- -France. Germany. Switzerland.
Galicia and Austria. Hungary. Servia. Italy. Norway.
Sweden, Denmark. Finland. N. Russia. Nova Zembla.
Greenland. Siberia. Japan. Burma. Australia. New
Zealand. United States. Patagonia. Antarctic.

The distinctive feature of St. aculeatum is the possession of
two series of spines stretching from angle to angle of the cell, a
dorsal series on the apex, and a lateral series lower down. The
median spines of the dorsal series are frequently emarginate,
and some of the spines of the lateral series may occasionally be
duplicated, or very much reduced in size, but the two series can
always be recognised.

153. St aura strum contr over sum Breb.
(PL CLIV, figs. 1-4.)

Stow/rostrum controversum Breb. in Menegh. Synops. Desrn. 1840, p. 228 ;

Ralfs, Brit. Desm. 1848, p. 141, t. 23, f. 3 ; Arch, in Pritch. Inf. 1861.

p. 742 ; De Not. Desm. Ital. 1867, p. 49, t. 4, f. 39 ; Wolle, Desm. U. S.

1884, p. 143, t. 45, f. 24, 25 ; Cooke, Brit. Desm. 1887, p. 173, t. 60,

f. 1 ; De Toni, Syll. Alg. 1889, p. 1216 ; West, Alg. N. Wales, 1890,

p. 19, f. 22 ; Alg. W. Ireland, 1892, p. 184 ; Roy & Biss. Scott. Desm.

1893, p. 18 ; Schmidle, Beitr. Algenfl. Rheineb. u. Schwarzwald. 1895,

p. 82, t. 1, f. 22 ; West & G. S. West, Alg. S. England, 1897, p. 496 ;

Liitkem. Desm. Millstiittersees, 1900, p. 20, t. 1, f. 49 ; Comere, Desm.

de France, 1901, p. 151, t. 11, f. 13 ; West & G. S. West, Alga-fl. Yorks.

1902, p. 106.

St. aculeatum Ralfs, in Ann. Mag. Nat. Hist. vol. 15, 1845, p. 156, t. 11, f. 13.
St. aculeatum var. controversum Rabenh. Flor. Europ. Alg. 1868, p. 217 ;

Jacobs. Desm. Danem. 1875, p. 207.

Cells usually under medium size, about as long as
broad, or up to 1| times broader than long, deeply con-

STAURASTRUM. 1 63

stricted, sinus acute, widening rapidly outwards ; semi-
cells subelliptical or fusiform, lower margin ventricose,
dorsal margin strongly convex ; lateral angles gradually
produced to form short, stout, strongly incurved processes,
tipped with about 3 spines and with 2 or 3 series of den-
ticulations beneath ; apex with a dorsal series of spines,
often deeply bifid, stretching from angle to angle, and
frequently with a lateral series just beneath as well.
Vertical view 3-5-radiate, angles produced into short
tapering processes all bent abruptly in one direction ;
lateral margins concave with a marginal row of spines,
often displaced by the twisting of the processes.

Zygospore roughly globose, somewhat angular, with
numerous short, much branched spines.

Length 25-65 u. ; breadth, including processes, 33-75 [i;
breadth of isthmus 7-1 2 ^ ; diam. zygosp., without
appendages, 27-37 ^ ; including appendages, 50-80 (JL.

ENGLAND. — Cumberland ! Westmoreland ! (Ralfs).
Lancashire ! W., N., and E. Yorks ! Leicester (Roy).
Burnham Beeches, Bucks ! Gloucester (Ralfs). Surrey !
Sussex (Ralfs). Hants ! Dartmoor, Devon (Harris).
Cornwall !

WALES. --Llyn Padarn !, Snowdon !, Capel Curig !
(Cooke & Wills), Llyn-y-cwm-ffynon !, Llyn Gwynant !
and Bettws-y-coed (Roy), Carnarvonshire. Dolgelly,
Merioneth (Ralfs).

SCOTLAND. — General (Roy & Biss.).

IRELAND. --Donegal ! Clare Isle, Mayo ! Kerry ! Dublin
and Wicklow (Arch.).

Geogr. Distribution.- -France. Germany. Galicia and
Austria. Italy. Norway. Sweden. Denmark. Finland.
L^nited States.

St. controversum is closely allied to St. aculeatum, from which
it differs in its relatively smaller size and its more strongly
developed and incurved processes, which are usually bent,
giving the specimens a very distorted appearance. It is a very
variable species, and the lateral series of spines is not always
present, but the dorsal row is usually very strongly developed.

164 BRITISH DESMIDIACE^E.

154. Staurastrum cosmospinosum (Borg.) West.

(PI. CLIV, figs. 5-7.)

Staurastrum aculeatum subsp. cosmospinosum Borg. Bornholm. Desm.-fL

1889, p. 147, t. 6, f. 8 : De Toni, Syll. Alg. 1889, p. 1218 ; West, Alg.

W. Ireland, 1892, p. 184.
St. rostelhim Roy & Biss. Scott. Desm. 1893, p. 24, t. 3, f. 3 ; Borg. Alg.

Faeroes, 1901, p. 233, t. 7, f. 15 ; Borge, Botan. Notiser, 1913, p. 50.
St. cosmospinosum West & G. S. West, Notes Alg. II, 1900, p. 295 ; Alg.

N. Ireland, 1902, p. 48; Notes Alg. Ill, 1903, p. 11 ; Brit. Freshw.

Phytoplankton, 1909, p. 202.

Cells rather under medium size, slightly longer than
broad, deeply constricted, sinus acute and open ; semi-
cells elliptical, dorsal margin rather more strongly
convex than the ventral, lateral angles scarcely produced,
but provided with a large spine more conspicuous than
the others and often drooping towards the sinus ; with
several other smaller spines scattered in the vicinity of
the angles ; apex of semicell with a row of spines, some
of which tend to become emarginate ; faces with de-
cussating rows of smaller spines arranged in about
4 vertical and 3 horizontal lines. Vertical view quad-
rangular, sides very slightly concave, angles scarcely
produced, lateral margins spiny and with 1 or 2 rows of
spines just within the margin.

Zygospore unknown.

Length 31-43 fi ; breadth 29-38 JJL ; breadth of isth-
mus 13-14[ji.

WALES. — Capel Curig, Carnarvonshire !

SCOTLAND. — Near Tain and Strathpeffer, Koss ; Glen
Sligachan in Skye, and Glen Nevis !, Inverness ; many
localities from Scotston to Girnoc, Aberdeen ; Rickarton,
Kincardine ; Glen Garry, Perth ; Glen Coe, Argyle (Roy
& Biss.}.

IRELAND. — Clifden to Roundstone, Galway ! Carran-
tuohill, Kerry ! Slieve Donard, Down !

Geogr. Distribution. — Sweden. Bornholm. Faeroes.
Azores.

STAURASTRUM. 1 65

155. Staurastrum Heimerlianum Liitkem.
(PL CXLIX, figs. 14, 15.)

Staurastrum cruciatum Heimerl, Desm. alp. 1891, p. 608, t. 5, f." 24.
-St. Heimerlianum Liitkem. Desm. Attersees, 1893, p. 568 ; West & G. S.
West. Alga-fl. Yorks. 1902, p. 105 ; Borge, Beitr. Alg. Schweden, 1906,
p. 46, t. 3, f. 38.

Cells small, lf-2 times broader than long, deeply con-
stricted, sinus acute-angled, widening towards the
exterior ; semicells narrowly fusiform, dorsal margin

•I O

less convex than the ventral, gradually attenuated
towards the poles to form long, parallel or slightly con-
verging processes, which have truncate apices and end
with 2 or 3 short spines ; upper margin of process
bearing a few stout spines, projecting almost perpen-
dicularly ; the lower margin usually with 2 ; spines
unequal in length. Vertical view usually quadrangular
(sometimes triangular), sides slightly concave, angles
produced to form stout processes, with 2 or 3 irregular
series of spines.

Zygospore subglobose, somewhat angular, bearing
irregular spines 1-3 times dichotomous at the apex.

Length 17-26(ji ; breadth, including processes, 29*4-
38 \L ; breadth of isthmus 6-8 tu. ; length of spines 1-4 pi ;
diam. zygosp., without appendages, 20-26 \L \ with
appendages, about 42 pi .

ENGLAND. — Cam Fell. W. Yorks !

Geogr. Distribution. — Germany. Austria. Sweden
(var.).

Var. spinulosum Liitkem. (PI. CXLIX, fig. 16.)

*S7. Heimerlianum var. spinulosum Liitkem. Desm. Attersees, 1893, p. 568,
t. 9, f. 17 ; Roy & Biss. Scott, Desm. 1893, p. 21 ; West & G. S. West,
Alg. S. England, 1897, p. 495.

Cells provided with regular series of spines, equal in
length, arranged in concentric series round the angles
and forming longitudinal rows in the front view ; centre of
apex smooth.

Length 21-26 pi ; breadth, including processes, 27-33 pi;
breadth of isthmus 9 pi ; length of spines about 2 pi.

166 BRITISH DESMIDIACE.E.

ENGLAND. — Thursley Common, Surrey !
SCOTLAND.- -Upper Powlair in Birse, Aberdeen ; pool
by the Spital Burn, Strachan, Kincardine (Roy &

Biss.).

Geogr. Distribution. — Austria. Scandinavia.

156. Staurastrum Sebaldi Reinsch.
(PL CXLVIII, figs. 5, 6.)

Staurastrum Sebaldi Reinsch, Spec. Gen. Alg. 1867, p. 133, t. 24 D, f. 1-3;
Nordst. Norges Desm. 1873, p. 33 ; Wolle, Desm. U. S. 1884, p. 138, t. 46,
f. 1-6; Cooke, Brit. Desm. 1887, p. 176; Borg. Bornh. Desm. 1889,
p. 148 ; De Toni, Syll. Alg. 1889, p. 1220 ; West, Desm. Massach. 1889,
p. 20, t, 3, f. 17 ; Alg. W. Ireland, 1892, p. 184 ; Eichler, Mat. Flor.
Miedz. 1894, p. 62 ; West & G. S. West, Some N. Amer. Desm. 1896,
p. 267, t. 18, f. 2, 3 ; Borg. Alg. Faeroes, 1901, p. 234.

Didymidium (Staurastrum} Sancti Sebaldi Reinsch, Algenfl. Frank. 1867,
p. 175, t, 11, f. 1.

Cells large, body of cell about 1| times longer than
broad, not including the processes, moderately con-
stricted ; sinus acute, opening widely ; semicells cup-
shaped, dorsal margin convex, angles produced to form
short, stout, tapering processes, which are usually slightly
converging and are tipped with 3 or 4 spines ; processes
with several concentric series of strong denticulations ;
apex of semicell with a row of large, simple, or 2-4-dentate
spines, and usually with a further row of simple spines
just beneath the apex, the lower series, however, variable
both in size and in character, sometimes even wanting.
Vertical view triangular, sides nearly straight, sometimes
a little convex, angles slightly produced into short den-
ticulate processes, with a series of simple or complex
spines within each lateral margin, which may itself be
spinous or not, according as the lower series of spines
is present or absent.

Zygospore unknown.

Length 73-85 ^ ; breadth, including processes, 69-
100 [Ji ; breadth of isthmus, about 24 [i.

ENGLAND.- -Bowness. Westmoreland ! Strensall !, Gor-
mire (W. B. Turn.}, and Pilmoor !, N. Yorks. Malham
Tarn, W. Yorks !

STAURASTRUM. 167

WALES. — Capel Curig ! (Cooke & Wills).

SCOTLAND.- -Locality ?

IRELAND.- -Near Oughterard, Galway ! Mayo and
Clare Island ! Carrantuohill, Kerry ! Dublin and Wick-
low (Arch.). Xear R. Black water, and south of Lough
Neagh, Armagh !

C_^J C_-

Geoyr. Distribution. — Germany. Galicia in Austria.
Hungary. Servia. Turkey. Norway. Sweden. Born-
holm. Finland. Poland. Faeroes. Iceland (form).
Greenland. Siberia (var.). India. Burma (form).
Australia. New Zealand (form). United States, Brazil,
(var.)

Unfortunately neither specimens nor good drawings of St.
Sebaldi Reinsch could be obtained for the purpose of the present
work, and apparently the figures reproduced on PI. CXLVIII
are not exactly typical. The vertical view is from a drawing by
Professor West of an American example, whilst PL CXLVIII,
fig. 5 was drawn by the present writer from a mounted prepara-
tion of Scottish specimens in the British Museum. West & G. S.
West (Alg. Burma,' 1907, p. 221, t. 16, f. 9) give some account of
St. Sebaldi, and it is evident from a study of their remarks that
PL CXLVIII, figs. 5 and 6, should both be considered atypical
in the fact that they lack a lower row of stout spines beneath
the apical row of emarginate spinous processes. In the vertical
view therefore the lateral margins should be typically spinous;
and not smooth. The general form of the specimen on PL
CXLVIII, fig. 5 is quite typical, and it is stated by the Wests
(loc. cit.) that the lower row of spines is variable both in size
and character. Their apparent variability may account for
their absence in the figures given. It is interesting to note
that Reinsch (' Contr. Alg. Fung.' 1875, t. ix, f. 4) also figures an
individual in which the lateral margins are smooth in the end
view, showing the absence of the lower series of spines,

Var. ornatum Nordst. (PL CXLVIII, fig. 7.)

St. Sebaldi var. ornatum Xordst. Xorges Desm. 1873, p. 34, t. 1, f. 15 ;
Cooke, Brit. Desm. 1887, p. 176, t. 61, f. 1 ; De Toni, Syll. Alg. 1889,
p. 1220 ; Turn. Alg. East India, 1893, p. 132; Roy & Biss. Scott. Desm.
1893, p. 25 ; Schmidle, Beitr. Algenfl. des Schwarzwald u. Oberrheins, VI,
1897, p. 23 ; West & G. S. West, Al.ira-fl. Yorks. 1902, p. 106; Alg. X.
Ireland. 1902, p. 56 ; Borge, Botan. Xotiser, 1913, p. 50.

168 BBITISH DESMIDIACE.E.

St. Sebaldi var. Cooke, in Grevillea, 1881, p. 92, t. 139, f. 5.
St. Sebaldi var. Cookeii Gutw. Wahr. d. Prioritat, 1890, p. 72 ; Flor. Glon.
Okolic Lwowa, 1891, p. 69.

Cells relatively more slender than in the type ; pro-
cesses much longer and more graceful, nearly parallel ;
semicells often with a group of verrucse near the sinus
at the base of each process.

Length 50-81 [x ; breadth, including the processes,
88-1 32 fx ; breadth of isthmus 15-22[A.

ENGLAND.- -Pilmoor, N. Yorks !

WALES. — Capel Curig ! (Cooke & Wills] and Llyn-y-
cwm-fTynon, Carnarvonshire ! In the plankton !

SCOTLAND. — Falls of Kogie, Eoss ; Brimmond, Slew-
drum, Aboyne, Powlair, near Dinnett, Tomacher, Aber-
deen ; Cammie, Kincardine ; Dirdie Moor, Perth (Roy
& Biss.). New Galloway, Kirkcudbright !

IRELAND. — Mayo ! Galway, and in the plankton !
Plankton of Lough Neagh !

Geogr. Distribution, — Germany. Norway. Sweden.
Finland. Australia. New Zealand.

St. Sebaldi var. ornatum is very similar in many ways to St.
Manfetdtii Delp. Its processes are, however, longer and more
graceful, and its granulation somewhat stronger.

Var. productum W. & G. S. West. (PI. CXLIX,

fig. 17.)

St. Sebaldi var. productum West & G. S. West, Further Contrib. Plankton
Scott. Lochs, 1905, p. 504, t. 7, f. 24 ; Compar. Study Plankton Irish
Lakes, 1906, p. 86.

Apex of semicell very slightly convex and quite
smooth, except for a series of about 6 emarginate verrucse
just within the margin ; angles produced to form long
verrucose processes ; vertical view triangular, sides
nearly straight and smooth, with a series of emarginate
verrucae within each lateral margin ; angles produced
into long verrucose processes.

Length 83 ^ ; breadth, including processes, 108-115 (jt;
breadth of isthmus 20 x.

STAURASTRUM. 1 69

SCOTLAND.- -Plankton of Lochs Fadaglioda and an
Sgath, Lewis, Outer Hebrides.
IRELAND. --Plankton of Gal way !
Geogr. Distribution.- -Finland.

Gronblad (' Desm. Keuru,' 1920, p. 76) has suggested making var.
productum a distinct species, including in it St. Traunsteineri
Hustedt ('Desm. Bacil. Tirol.' 1911, p. 340), which he considers
to be merely a form of West's alga.

157. Staurastrum oxyacanthum Arch.
(PL CXLIII, figs. 18, 19.)

St. oxyacanthum Arch, in Quart. Journ. Micr. Sci. 1860, p. 757, t. 7, f. 1, 2 ;
in Pritch. Inf. 1861, p. 742 ; Rabenh. Krypt. Flor. Sachs. 1863, p. 193 ;
Flor. Europ. Alg. 1868, p. 219 ; Arch, in Quart. Journ. Micr. Sci. 1872,
p. 89 ; Cooke, Brit. Desm. 1887, p. 175, t. 60, f. 4 ; Borg. Bornholm. Desm.-
fl. 1889, p. 147 ; De Toni, Syll. Alg. 1889, p. 1219 ; Heimerl, Desm. alp.

1891, p. 607 ; West, Alg. W. Ireland, 1892, p. 184 ; Alg. Eng. Lake Distr.

1892, p. 20 ; Roy & Biss. Scott. Desm. 1893, p. 23 : West & G. S. West,
Alg. S. England,' 1897, p. 496 ; Alga-fl. Yorks. 1902, p. 106 ; Hustedt,
Desm. Bacill. Tirol, 1911, p. 340; West & G. 8. West, Brit. Freshw.
Phytoplankton, 1909, p. 203.

St. scorpioideum var. brevis Gutw. Wahr. d. Prioritat, 1890, p. 72.

Cells small, about 1| times broader than long, includ-
ing the processes, deeply constricted, sinus acute,
approximately rectangular ; semicells short, subfusi-
form or subcuneate, dorsal margin slightly convex,
ventral margin very tumid, semicells produced at the
angles to form long slender processes, very slightly con-
verging, tipped with about 3 minute spines and with
3 or 4 concentric series of minute denticulations ; apex
of semicell armed at the origin of each process with a
pair of fairly long spreading spines. Vertical view 2-4-
(usually 3-) angled, sides straight and smooth, with a
pair of stout spines projecting from just within each
margin, angles produced to form denticulate processes.
Chloroplast axile, with a central pyrenoid in each semi-
cell, and a pair of plates projecting into each angle.

Zygospore unknown.

Length 26-29 \L ; breadth, including processes, 36-40^;
breadth of isthmus 9 '6-10^.

ENGLAND.- -Loughrigg !, and near Bowness (Bissett),

170 BPxITISH DESMIDIACE^E.

Westmoreland. Cocket Moss, near Giggleswick and
Austwick Moss, W. Yorks ! Riccall Common, E. Yorks !
Tliursley Common, Surrey !

WALES.- Bethesda and Capel Curig, Carnarvonshire !

SCOTLAND.- -Ross, Inverness, Aberdeen, Kincardine,
Forfar, Perth, Argyle, and Arran (Roy & Biss.).

IRELAND.- -Donegal ! Galway ! Kerry! Sugar Loaf
Mountain, Cork (Arch.} Dublin and Wicklow (Arch.}.

Geogr. Distribution. — Germany. Switzerland. Austria.
Sweden. Bornholm. Finland. Poland (var.). N. Russia.
Faeroes. Greenland. Siberia. Mongolia. Patagonia
(var.).

The characteristic spines and slightly incurved processes dis-
tinguish this species from all others. It is a frequent Desmid in
the western areas of the British Isles, although rarely seen outside
those districts. Archer reports the occurrence of different
combinations of 2, 3 or 4-radiate forms in the same individual.

x

Var. polyacanthum Nordst. (PL CXLIII, figs. 20-22.)

St. oxyacanihum var. polyacanthum Nordst. Desm. Gronland, 1885, p. 11,
t. 7, f. 9 ; De Toni, Syll. Alg. 1889, p. 1219 ; Anders. Sverig. Chloroph.
1890, p. 12 ; Livtkem. Desm. Millstattersees, 1900, p. 23.

Cells similar in form to the type, but larger, and with
slightly longer and rather more slender processes ; semi-
cells in front view with a number of scattered spines just
beneath the apex, sometimes occurring in two horizontal
series ; body of semicell with 2 or 3 short series of

«/

granules under each process. Vertical view usually
triangular, sides straight with about 2 parallel marginal
series of spines, spines numerous and sometimes scat-
tered; basal view of semicell with several short concentric
series of granules extending from the denticulations of
the processes to the isthmus, the innermost series being
larger and forming a concrescent verruca.

Length 41-48 \i ; breadth, including processes, 59-68 ^;
breadth of isthmus 11-13 \L.

ENGLAND. — Austwick Moss, W. Yorks (N.C.).

WALES.- -Llvn Ogwen, Carnarvonshire !

«/' C?

Geogr. Distribution. — Austria. Sweden. Greenland.

STAUEASTEUM. 171

158. Staurastrum dorsidentiferum W. & G. S. West.

(PL CXLVIII, fig. 4.)

Staurastrum dorsidentiferum West & G. S. West, Coinp. Study Plankton
Irish Lakes, 1906, p. 103, t. 11, f. 10; British Freshw. Phytoplankton,
1909, p. 202.

Cells large, about 1^ times broader than long, including

O ' £* O O

the processes, constriction fairly deep, sinus open and
obtuse at the apex ; semicells smooth and cup-shaped,
apex generally flattened and gently undulate, angles
produced to form long stout processes projecting nearly
horizontally, and tipped with 4 teeth ; lower margin of
each process crenulate, upper margin also ere mil ate, but
the median 3-6 (usually 5) crenations bearing acute,
erect teeth ; vertical view triangular, sides slightly
convex, angles produced to form long processes, with
undulate margins, and a single row of spines along each.

Zygospore unknown.

Greatest length 75-79 \± ; breadth, without processes,
about 48 {Jt ; with processes, 1 08-1 20 [i ; breadth of
isthmus 1 8 [A.

IRELAND. --Plankton of Loughs Conn and Cullin,
Mayo ! Lough Corrib, Gal way !

The direction of the processes in the front view is somewhat
variable. In some specimens they are rather upwardly diver-
gent, but in the majority they are horizontally disposed. The
number of teeth affixed to the crenations of the upper margins of
the processes is also variable, even on the processes of the same
plant. The species is confined to plankton and should be
compared with St. gracile Ralfs and St. Sebaldi Reinsch. Its
large cells, smooth except for the row of stout spines on the top
of each process, distinguish it from all other species.

159. Staurastrum aciculiferum (West) Anders.
(PL CXXXIV, fig. 6.)

St. Aricitla Tar. aciculiferum West, Add. Alg. W. Yorks. 1889, p. 293,

t. 291, f. 12 ; Alg. N. Wales, 1890, p. 16.
St. aciculiferum Anders. Sverig. Chlor. 1890, p. 11, t. 1, f. 4; West & G. S.

West, Alga-fl. Yorks. 1902, p. 98 ; Alg. N. Ireland, 1902, p. 47 ; Borge,

Beitrage Alg. Schweden, 1906, p. 45.

172 BRITISH DESMIDIACE.E.

Cells small, about as long as broad, including the
processes, deeply constricted, sinus widely open ; semi-
cells elliptical, dorsal margin only slightly convex,
ventral margin more strongly so ; semicells produced at
the angles to form short solid processes deeply bifid at
the apex, the two teeth lying in the same vertical plane ;
with two accessory spines (also occasionally bifid),
projecting almost vertically from the apex between each
pair of angles. Vertical view triangular, sides very
slightly convex, angles broadly rounded and then
slightly produced into a short solid process, with a pair
of simple or bifid spines projecting from the apex across
each lateral margin. Cell-wall with about 2 obscure
series of minute granules round each angle.

Zygospore unknown.

Length 21-30 pi ; breadth 22-34 (j- ; breadth of isth-
mus 5-9 \JL .

ENGLAND.- -Helvellyn, Westmoreland ! Cocket Moss,
near Giggleswick ; Penyghent ; Whernside ; Mossdale
Moor, Widdale Fell, W. Yorks ! Mickle Fell and Lund's
Fell, N. Yorks !

WALES. — Moel Siabod, bog between Glyder Fach and
Llugwy, y Foel Fras, and Tal-y-fan, Carnarvonshire !
Ffestiniog, Merioneth !

SCOTLAND.- -Hoy, Orkneys !

IRELAND. — Near Gweedore, Donegal ! Achill Island
and Clare Island, Co. Mayo ! Boggy inlet of Lough
Neagh.

Geogr. Distribution. — Sweden. United States.

St. aciculiferum really has very little affinity with any other
species of Section I, but strictly speaking it belongs here. It was
originally described as a variety of St. Avicula, but whereas the
angular spines of this species are attached separately to the
' body ' of the semicell, in St. aciculiferum there is a distinct
though short solid process, deeply bifid at its apex. The apical
spines may be considered well developed denticulations of the
series of small granules round the angles ; they are very often
bifid.

STAURASTRUM. 173

SECTION J.

Semicells with accessory processes, mostly of dorsal origin.
* Processes quite smooth.

| All the processes short, less than half the diameter of
the " body " of the cell in length.

160. St.furcatum.

161. St. senarium.

162. St. gemelliparum.
ft Processes longer, nearly as long as the body of the cell

is broad, and frequently longer.

163. St. Clevei.

164. St. Tohopekaligense.
** Processes rough with granules or denticulations.

t At least the dorsal processes short, and angular processes,
never attaining very great length.

165. St. arcuaturn.

166. St. subavicula.

167. St. amphidoxon.

168. St. meg alo notion.

169. St. monticulosiuii .

170. St. diplacanthum.

171. St. Westii.
161. St. senfii-imn.

172. St. forficulatum.

173. St. furdgerum.
ft All the processes of considerable length.

174. St. Arctiscon.

175. St. sexaugulare.

160. Staurastrum furcatum (Ehr.) Breb.
(PL CLV, figs. 1-4.)

Xanthidium furcatum Ehr. Inf. 1838, p. 148, t. 10, f. 25 ; Menegh. Synops.

Desm. 1840, p. 224 ; Ralfs, Brit. Desm. 1848, p. 213.
? X. Ehrenbergii Corda, Aim. de Carlsbad, 1840, p. 214, t. 5, f. 36, 37.
stnumstrum spinosum Ralfs, Brit. Desm. 1848, p. 143, t. 22, f . 8 ; De Bary,

Conj. 1858, p. 44 ; Reinsch, Contrib. Alg. et Fung. 1875, p. 90, t. 10, f. 3 ;

Heimerl, Desm. Alp. 1891, p. 007.
Phycastrum (P achy actinium] Ehrenbergianum Nag. Gatt. einz. Alg. 1849,

p. 128.

Asteroxanthium furcatum Kiitz. Spec. Alg. 1849, p. 183.
Staurastrum furcatum Breb. Liste Desm. 1856, p. 136 ; Arch, in Pritch.

Infus. 1861, p. 743 ; Rabenhorst, Flor. Europ. Alg. 1868, p. 218 (in part) ;

Nordst. Norges Desm. 1873, p. 33 ; Kirchn. Alg. Schles. 1878, p. 170 ;

Wolle, Desm. U. S. 1884, p. 150, t. 40, f. 40, 41 ; Cooke, Brit. Desm. 1887,

p. 146 ; De Toni, Syll. Alg. 1889. p. 1153 ; West, Alg. N. Wales, 1890,

p. 16, f. 11 ; Alg. W. Ireland, 1892, p. 174 ; Alg. Engl. Lake Distr. 1892,

p. 19 ; Roy & Biss. Scott. Desm. 1893, p. 20 ; Liitkem. Desm. Attersees,.

174 BRITISH DESMIDIACE^E.

1893, p. 563 ; West & G. S. West, Alg. S. England, 1897, p. 493 ; Comerc,

Desm. cle France, 1901, p. 165, t. 13, f. 21 ; West & G. S. West, Brit.

Kreshw. Phytoplankton, 1909, p. 203.

I >',(!)/ in iili /i in (Staurastrum) spinosum Reinsch, Alg. Frank. 1867, p. 168.
tStau rast rum furcatum var. armigerum Cooke, Brit. Desm. 1887, p. 146,

t. 51, f. 1.

>V. conmbiense Benn. Alg. N. Cornwall, 1887, p. 11, t. 4, f. 24.
,SV. De Tonii Eichler & Gutw. Nonn. Spec. alg. nov. 1894, p. 18, t. 5, f. 51.

Cells small, about as long as broad (including the
processes), or sometimes slightly longer or shorter than
broad, deeply constricted, sinus acute and open ; semi-
-cells subelliptical or subglobose, dorsal and ventral
margins almost equally convex, lateral angles produced
to form short, stout, nearly horizontal processes, with
bifid apices, the two teeth lying in the same vertical
plane ; apical margin of each face of the semicell with
two short bifid processes, which are nearly erect ; cell-
wall smooth, or very minutely punctate. Vertical view
triangular, angles scarcely produced, ending in a spine,
sides straight or very slightly concave, with 2 short
bifid processes projecting from each lateral margin.

Zygospore globose, with numerous spines bifid at the
apex (Rolfs}.

Length, including processes, 25-33 \L ; breadth, in-
cluding processes, 20-40^ ; breadth of isthmus 6-10^ ;
diam. zygosp., without processes, 33 \i ; including pro-
cesses 57 '5 {A.

ENGLAND. — Cumberland ! Westmoreland ! Strensall
Common ! (W. B. Turner) and Pilmoor ! N. Yorks !
Leicestershire (Roy}. War wicks (Wills). Surrey ! (Rolfs}.
Dartmoor, Devon (Harris}. Cornwall !

WALES.- -Fairly general! (at 2200 feet on Glyder
Each). In the plankton !

SCOTLAND. — General ! (Roy & Biss.}. In the plankton !

IRELAND. Donegal ! Mayo ! Galway ! Kerry !
Dublin and Wicklow (Arch.).

Geogr. Distribution.- -France. Germany. Switzerland.
Galicia and Austria. Hungary. Turkey. Norway.
Sweden. Denmark. Bornholm. Finland. Poland.
N. and S. Russia. Iceland. Japan. India. Australia.
United States.

STAURASTRUM. 175

Cooke (' Brit. Desm.' 1887, p. 147, t. 53, f . 6) figures a Desmid
which he attributes to St. furcatum var. candianum (Delp.)
Cooke (see PL CLV, fig. 5). Cooke's figure, however, shows
granulations round the lateral angles, which would indicate
greater affinity with St. subavicula West than with St. furcatum.
There is no indication of granulation in St. candianum Delp.
(' Desm. subalp.' 1877, p. 140, 1. 11, f. 22-24 ; see PL CLV, fig. 6).
Harris ('Desm. Dartmoor,' 1917, p. 29) has also recorded St.
furcatum var. candianum (Delp.) Cooke. It is probable that this,
too, would have been better referred to St. subavicula West.

Var. subsenarium W. & G. S. West. (PL CLV, fig. 7.)

St. furcation var. subsenarium West & G. S. West, >iew Brit. Fresrnv. Alg.
1894, p. 10, f. 53 ; Alg. S. England, 1897, p. 493 : Gronblad, Desm.
Keuru, 1920, p. 65, t. 3, f. 52, 53.

This variety has a simple spine beneath each dorsal
process.

Length, without processes, 20-29 \L ; breadth, includ-
ing processes, 25-39 [/. ; without processes, 18-32'ou;
breadth of isthmus 8-9'5ti.

ENGLAND. - - Scandale, Westmoreland ! Dartmoor,
Devon !

WALES.- -Llyn Idwal (N. C.).

IRELAND.- -Leenane to Westport, Mayo !

Geoar. Distribution.- -Finland.

ij

This variety differs from the typical form in the possession
of concentric series of granules round the angles of the semicell
as well as in the additional spines.

161. Staurastrum senarium (Ehr.) Ralfs.
(PL CLVI, fig. 3.)

Desmidium senarium Ehr. Micr. Leb. S. & N. Amer. 1843, p. 412, t. 4, f. 22.
Staurastrum senarium Ralfs, Brit. Desm. 1848, p. 216 ; Arch, in Pritch.

Inf. 1861, p. 742, t. 2, f. 7 ; Rabenh. Flor. Europ. Alg. 1868, p. 220;

Lund. Desm. Suec. 1871, p. 66 ; Nordst. Desm. Spetsb. 1872, p. 41 ;

Wolle, Desm. U. S. 1884, p. 147, t. 52, f. 1 ; De Toni, Syll. Alg. 1889,

p. 1155 ; Turn. Alg. E. India, 1893, p. 119, t. 15, f. 13 ; G. 8. West, Alg.

Yan Yean, 1909, p. 68, t. 6, f. 13 ; Alg. Colombia, 1912, p. 1045.
Stephanoxanthium senarium Kiitz. Spec. Alg. 1849, p. 184.
Staurastrum furcatum var. senarium Joshua, Desm. Burma, 1886, p. 643.

Cells small, about If times broader than long, deeply
constricted, sinus acute and open ; semicells elliptical

176 BRITISH DESMIDIACE^}.

or subfusiform, lateral angles gradually produced into
short processes with bifid spreading apices ; with two
accessory processes on the faces of the semicell between
each two consecutive angular processes and in the same
horizontal plane with them, and with two other pro-
cesses projecting from the apical margin of each face
immediately above the accessory processes of the lower
whorl ; processes smooth, or the angular ones sometimes
with a circle of minute denticulations. Vertical view
triangular, angles very slightly produced ; sides
gently concave, each with 2 bifid processes projecting
from its margin, and with 2 others just within the margin
on the apex.

Zygospore unknown.

Length 42-46 pi ; breadth, including processes, 46-
58 JJL ; breadth of isthmus 11-1 5 (x.

ENGLAND.- -Bowness, Westmoreland !

IRELAND.- -Dublin and Wicklow (Arch.).

Geogr. Distribution. — Germany. Galicia in Austria.
Norway. Sweden. Bornholm. Finland. Poland. Spitz-
bergen (form). India. Burma. Australia. United States.
Colombia.

St. senarium is closely allied to St. furcatum Ehr., from which
it differs in the possession of 15 processes, instead of 9. The
processes are arranged one at each angle, with 6 others in the
same plane as these 3 angular ones, and a dorsal series of 6 on
the apex. The presence of denticulations on the angular pro-
cesses is of little importance, since they are sometimes present
in one semicell of an individual and absent from the other.

162. Staurastrum gemelliparum Nordst.
(PL CLVI, fig. 5.)

Staurastrum gemelliparum Nordst. Desm. Brasil, 1869, p. 230, t. 4, f. 54;
Wille, Sydamerik. Alg.-fl. 1884, p. 21 ; De Toni, Syll. Alg. 1889, p. 1175 ;
West & G. 8. West, Alg. Ceylon, 1902, p. 179, t. 21, f. 25 ; Borge, Sao
Paulo Alg. 1918, p. 54, t. 4, f. 25.

Cells small, about as long as broad, or a little longer,
deeply constricted, sinus open and acute ; semicells
subelliptical, dorsal margin nearly straight, ventral

STAURASTRUM. 177

margin more convex ; each angle of the cell with 4 pro-
cesses, an upper pair and a lower pair, processes bifid
at the apex, the two teeth lying in the same vertical
plane. Vertical view triangular, sides slightly concave,
angles broadly truncate and bifid, a lower pair of short
processes visible under an upper pair at each angle.
Cell- wall smooth or minutely punctate.

Zygospore unknown.

Length, without processes, 17-25 y, ; including pro-
cesses, 26-30 fji ; breadth, including processes, 20-26 y. ;
breadth of isthmus 7*7-10[i.

SCOTLAND. — Glen Shee, Perth !

Geogr. Distribution.- -Poland (form). Ceylon. United
States. Colombia (form). Brazil.

This species should be compared with St. quadrangulare Breb.,
which differs in the possession of four solid spines at each angle.

163. Staurastrum Clevei (Wittr.) Eoy & Biss.

(PL CLVI, fig. 6.) I

Staurastrum Icece Cleve, Sverig. Desm. 1863, p. 490.

St. Iceve var. Clevei Wittr. Skand. Desm. 1869, p. 18, t. 1, f. 9 ; Arch, in
Quart. Journ. Micr. Sci. vol. ii, 1871, p. 92 ; Cooke, Brit. Desin. 1887,
p. 180, t. 63, f. 3 ; Eichler, Mat. Flor. Miedz. 1894, p. 62.

St. KitcMlii Wolle, Desm. U. S. 1884, p. 150, t. 40, f. 35, 36 ; De Toni, Syll.
Alg. 1889, p. 1155 ; West & G. S. West, Desm. U. S. 1898, p. 319, t. 18,

f. 10, 11.

St. Clevei Roy & Biss. Scott. Desm. 1893, p. 18 ; Wittr. & Nordst. Alg.
Exs. fasc. 35, 1903, p. 12 ; West & G. S. West, Further Contrib. Plankton
Scott. Lochs, 1905, p. 503 ; Brit. Freshw. Phytoplankton, 1909, p. 202.

Cells rather under medium size, slightly longer than
broad, excluding the processes, deeply constricted, sinus
acute and open ; semicells subelliptic, lower margin
strongly ventricose, dorsal margin slightly convex,
lateral angles gradually produced to form fairly long
processes, deeply bifid with spreading apices in the same
vertical plane ; each face of the semicell with another
process, inserted obliquely near to each angular process.
Vertical view triangular, angles produced to form pro-
cesses, sides slightly convex, apex with an accessory

VOL. v. 12

178 BRITISH DESMIDIACE^E.

process projecting obliquely across each lateral margin
near the angle. Cell-wall smooth.

Zygospore unknown.

Length, without processes, 30-32 [JL ; including pro-
cesses, 52-61 [Ji ; breadth, including processes, 50-57 [j.;
breadth of isthmus 11 '5-17^.

SCOTLAND. — Brin, and in Skye, near Loch Cornisk,
Inverness ; Glen Coe, Argyle (Roy & Biss.}. Rhiconich,
Sutherland ! Plankton of Loch Fadaghoda, Lewis, Outer
Hebrides !

IRELAND.- -Kylemore, Co. Galway (Arch.).

Geogr. Distribution. — Norway. Sweden. Finland.
United States.

164. Staurastrum Tohopekaligense Wolle.
(PL CLV, fig. 12.)

Staurastrum Tohopekaligense Wolle, in Bull. Torr. Bot. Club. 1885, p. 128,
t. 51, f. 4, 5 ; Freshw. Alg. U. S. 1887, p. 45, t. 59, f . 4, 5 : De Toni, Syll.
Alg. 1889, p. 1162 ; West & G. S. West, Alg. Ceylon, 1902, p. 180 ; Alg.
Third Tanganyika Exp. 1907, p. 130, t. 3, f. 15.

Cells large, about 1| times longer than broad, without
the processes, deeply constricted, sinus acute, narrow
at first, then opening widely ; semicells broadly oval or
subglobose, lateral angles produced to form long slender
processes usually with bifurcate spreading apices ; often
with 2 other similar processes between each pair of
angular processes ; with a further dorsal series of pro-
cesses, two of which project between each pair of
consecutive angles. Vertical view triangular or
quadrangular, sides straight or very slightly concave
or convex, angles produced into long slender processes,
with a pair of dorsal processes projecting from each
lateral margin, and frequently with a pair of processes
also on the same plane as the angular processes beneath
the dorsal series.

Zygospore unknown.

Length, without processes, 29-51 \i ; with processes,
48-91 \L ; breadth, without processes, 23-40 (x ; with
processes, 46-96 [i ; breadth of isthmus 13-19 ku.

STAURASTRUM. 179

^ Geogr. Distribution.- -Finland. India, Central Africa.
United States.

This species exhibits a certain amount of variation in size,
in the form of the body, and in the length of the processes.
There are two whorls of processes on each semicell, the lower
whorl consisting (in the triradiate form) either of 3 processes
(one at each angle), or of 9 processes (one at each angle and a
pair on each lateral margin), and the upper whorl consisting of
6 processes. Thus the total number of processes on each semi-
cell is either 9 or 15 in the triradiate form. Each process is
very slightly dilated at the end, and is usually bifurcate, occasion-
ally trifurcate, and the lobes are hollow to the tip.

Var. trifurcatum W. & G. S. West. (PI. CLV, figs.

13, 14.)

St. TohopeJcaligense var. trifurcatum West & G. S. West, Alg. Madagas. 1895,
p. 80, t. 9, f. 8 ; Alg. Ceylon, 1902, p. 181, t. 21, f. 27 ; Further Contrib.
Plankton Scott. Lochs, 1905, p. 503, t. 7, f. 7.

This variety is characterised by its slightly shorter
processes, with strong trifid spreading apices ; processes
usually 3 at each angle, less spreading in the front view.
Chloroplast axile with a central pyrenoid.

Length, without processes, 36-45 (x ; including pro-
cesses, 54-75 (Ji ; breadth, without processes, 27-32 y* ;
including processes, 50-70 pt ; breadth of isthmus 9'5-

14(JL.

SCOTLAND.- -Rhiconich, Sutherland ! Plankton of
Loch Fadaghoda, Lewis, Outer Hebrides !

Geogr. Distribution. — Ceylon. Australia. Madagascar.

This variety, like the type, exhibits considerable variation.
The British examples had always the smaller number of pro-
cesses in the lower whorl, i. e. 3 in the triangular form and 4 in
the quadrangular form, but specimens from Ceylon have been
seen in which there were 9 lower processes in a triangular speci-
men. The trifid apices of the processes are not constant either,
for in the specimens from Loch Fadaghoda the processes of the
upper whorl were frequently bifid.

180 BRITISH DESMIDIACE.E.

165. Staurastrum arcuatum Nordst.
(PL CLV, fig. 8.)

Staurastrum arcuatum Nordst. Norges Desm. 1873, p. 36, t. 1, f. 18 ; Cooke,
Brit. Desm. 1887, p. 169, t. 51, f. 2 ; Boldt, Desm. Gronland, 1888, p. 40 ;
De Toni, Syll. Alg. 1889, p. 1207 ; West, Freshw. Alg. Maine, II, 1891,
p. 4, t. 15, f. 13 ; Alg. W. Ireland, 1892, p. 181 ; Turner, Alg. E. India,
1893, p. 120, t. 14, f. 20 ; Roy & Biss. Scott. Desm. 1893, p. 17 ; West
& G. S. West, Alg. S. England, 1897, p. 493; Liitkem. Desm. Mill-
stattersees, 1900, p. 19; Comere, Desm. de France, 1901, p. 156, t. 11,
f. 16 ; Bohlin, Flor. alg. d^ores, 1901, p. 64, t. 1, f. 26 ; Cushman in.
Bull. Torr. Bot. Club, 1907, p. 164.

Cells small, about \\ times broader than long, deeply
constricted, sinus acute and opening widely; semicells
elliptical, diverging or externally lunate, angles slightly
produced, ending in two stout diverging spines which
lie in the same vertical plane; dorsal margin straight,
ventral margin convex, cell-wall rough with granules,
arranged in concentric series round the angles. Vertical
view triangular, sides concave, angles produced and
tapering, with a pair of small bifid processes at the
base of each ; cell- wall smooth in the centre.

Zygospore unknown.

Length, without processes, 20 \i ; breadth, without
processes, 29 JJL ; including processes, 32 \L ; breadth of
isthmus 9 JJL .

ENGLAND. Brandreth, Westmoreland ! Epping
Forest, Essex ! New Forest, Hants ! Gunwen Moor,
Cornwall !

SCOTLAND.- -Pool beside Loch Dawan, Dalbagie, and
in Glen Clunie, Aberdeen (Roy & Biss.).

IEELAND.- -Lakes east of Lough Bofin, Gal way !
Near Lough Brin, Kerry ! Dublin and Wicklow (Arch.).

Gedgr. Distribution.-- France. Germany. Austria.
Servia. Greenland. Central China (var.). Japan. India.
Azores. United States. Colombia.

Var. Guitanense West. (PL CLV, fig. 9.)

St. arcuatum var. Guitanense West, Alg. W. Ireland, 1892, p. 181, t. 23, f. 10.

Differs from the type in its relatively greater length
and broader isthmus, angles produced into shorter

STAURASTRUM. 181

processes, with more delicate spines, dorsal processes
shorter.

Length, without processes, 25 y. ; breadth, including
spines, 40^ ; breadth of isthmus 14(ju

IRELAND.- -Lough Guitane, Kerry !

166. Staurastrum subavicula W. & G. S. West.

(PL CLY, fig. 10.)

,S7. arcuatuni var. subavicula West, Alg. Engl. Lake Distr. 1892, p. 20, f. 25.
-SV. .siibiin'cuhi \Vest & G. S. West, New Brit, Alg. 1894, p. 12.
.s7. arcuatuni var. vastuni Schmidle, Alg. Bern. Alps, 1894, p. 94, t. 6, f. 7.
St. vastum Schmidle, Beitr. Alp. Alg. 1896, p. 31.

Cells about as long as broad, or a little longer, includ-
ing the processes, deeply constricted, sinus open, almost
rectangular ; semicells subelliptical, or cuneate, apex
and lateral margins nearly straight or slightly convex :

o «/ v

upper angles scarcely produced, ending in two spines,
and with two series of granules just beneath, apex of
each face with a pair of short bifid processes. Vertical
view triangular, sides concave, angles rounded with two
spines, one beneath the other, apex with a circle of
6 bifurcate processes ; centre of apex smooth.

Zygospore unknown.

Length 32 \L ; breadth 32-32'o \L ; breadth of isth-
mus 9'5 fj..

ENGLAND.- -Harrop Tarn, Westmoreland !

WALES. — Glyder Fawr, Carnarvonshire !

Geoyr. Distribution. — Germany. Australia.

167. Staurastrum amphidoxoii West.
(PL CLV, fig. 11.)

stnuit ampludoxon West & G. S. West, New Brit. Freshw. Alg. 1894,
p. 10, t. 1, f. 17.

Cells small, nearly twice as broad as long, deeply
constricted ; semicells subelliptical, rough with granules
arranged in concentric series round the angles, apex
nearly straight, ventral margin convex, angles produced

182 BRITISH DESMIDIACE^.

into short processes with 3 tiny spines at their apex.
Vertical view triangular, sides concave, and with two
short diverging processes with bifid apices at the base
of each angular process.

Zygospore unknown.

Length, 22*5 [i ; breadth, including processes, 39 [i ;
breadth of isthmus 13 '5 y*.

SCOTLAND. — New Galloway, Kirkcudbright !

Geogr. Distribution.- -W '. Greenland (var.).

This species seems to be very closely allied to St. arcuatum
Nordst. Its lateral angles are, however, not so divergent as in
that species, nor are the apical processes so long or erect. In
the vertical view the angles are also distinctly inflated in St.
arcuatum, whereas in St. amphidoxon the body of the cell gradually
tapers at the angles into the processes.

168. Staurastrum megalonotum Nordst.
(PL CLIV, fig. 13.)

Staurastrum megalonotum Nordst. Desm. Arctoae, 1875, p. 35, t. 8, f. 38 ;
Boldt, Desm. Gron. 1888, p. 39 ; De Toni, Syll. Alg. 1889, p. 1222 ; Cush-
man in Rhodora, 1905, p. 263.

Cells of medium size, nearly as long as broad, deeply
constricted, sinus open arid acute ; semicells in front
view subhexagonal fusiform, apex somewhat produced,
truncate or slightly concave, upper angles ending in a
spine, lateral angles produced slightly and also ending
in a spine, upper margin of lateral angles gently con-
cave, lower margins nearly straight ; angles provided
with several series of denticulations. Vertical view
quadrangular, sides concave, angles slightly pro-
duced, ending in a spine, and with concentric acute
denticulations, lateral margins with acute granules near
the angles, but smooth in the median part, with two
spines or spinulose processes just within each lateral
margin ; centre of apex smooth.

Zygospore unknown.

Length, without spines, 42-46 (j. ; breadth, including
spines, 62 \L ; breadth of isthmus 16-21 [i.

STAURASTRUM. 183

ENGLAND.—? Mickle Fell, N. Yorks !
Geocjr. Distribution. — Germany (form). Austria (form).
Spitsbergen. Greenland.

This alga is extremely rare in the British Isles. There is only
one doubtful record for it from Yorkshire.

169. Staurastrum monticulosum Breb.
(PL CLIV, fig. 8.)

Binatella monticulosa Breb. in Chev. Micr. 1839, p. 27i'.

Staurastrum tiwnticulosutn Breb. in Menegh. Synops. Desm. 1840, p. 226 ;

Ralfs, Brit. Desra. 1848, p. 130, t. 34, f. 9 ; Arch. Suppl. Cat. Desm. 1858, p.

257, t. 21, f. 1(3 : in Pritch. Inf. 1861, p. 739 ; Rabenh. Krypt,-fl. Sachs.

1863, p. 192 ; Flor. Europ. Alg. 1868, p. 214 ; Lund. Desm. Suec. 1871,

p. 65 ; Jacobs. Desm. Danemark, 1875, p. 209 ; Cooke, Brit. Desm. 1887,

p. 147, t. 5<>. t. 10; De Toni, Syll. Alg. 1889, p. 1156; Comere, Desm.

de France, 1901, p. 166, t, 12, f.*3 ; Borge, Botan. Xotiser, 1913, p. 50 ;

Gronblad. Desm. Keuru, 1920, p. 87.

Phycastrum monticulosum Kiitz. Phyc. Germ. 1845, p. 138.
Stephanoxtinthium inonticuh>siun Kiitz. Spec. Alg. 1849, p. 184.

Cells rather under medium size, very slightly longer
than broad, deeply constricted, sinus open and acute ;
semicells subtrapeziform, lower lateral margins slightly
convex, upper lateral margins distinctly concave, lateral
angles truncate with two spines lying in the same vertical
plane ; apex of semicell straight or slightly concave,
with a pair of short conical processes, tipped with spines,
at each upper angle of the semicell (usually only 4
of these are visible) ; angles of semicell with several
concentric series of small granules. Vertical view
usually triangular, sides straight or very slightly convex,,
with two spinate projections just within each margin;
angles subacute, ending in two spines (one above the
other), and with several series of granules.

Zygospore unknown.

Length, including spines, 40-57 \L ; breadth, including
spines, 35-42 [z ; breadth of isthmus 13-19[ji.

ENGLAND. --Xear Bowness, Westmoreland (Biss.).
? Cowgill Wold Moss, Widdale Fell, W. Yorks ! Pilmoor,
N. Yorks ! Penzance, Cornwall (Ralfs). Dartmoor
(Harris).

184 BEITISH DESMIDIACE^E.

WALES. — Capel Curig (Roy) and Glyder Fawr ! Car-
narvonshire.

SCOTLAND.- -Loch Luichart, Ross (N. C.).

IRELAND. — Carrantuohill, Kerry ! Dublin and Wick-
low (Arch.}. Clare Island, Mayo !

Geogr. Distribution. — France. Germany. Austria.
Servia. Norway. Sweden. Denmark. Bornholm.
Finland. N. Russia. Greenland. Siberia (var.). Japan.
United States.

Typical St. monticulosum is not a common Desmid in the
British Isles, var. bifarium Nordst. being much more frequently
found. Apparently W. & G. S. West did not thoroughly under-
stand this species, for PL CLIV, fig. 11 is a drawing showing
their idea of the typical form. This obviously does not belong
to St. monticulosum, however, and the localities for the species
with the Wests' authority (shown !) should consequently not be
taken as correct. PL CLIV, fig. 8 is a drawing by the present
writer from L. Luichart, and it agrees exactly with a drawing of
Gronblad (Act. Soc. Flor. Fauna Fenn.' 47, 1920, p. 90), who
has recently examined de Brebisson's original specimens, and
gives a good review of the species and its various varieties.

Var. bifarium Nordst. (PI. CLIV, fig. 9.)

St. monticulosum var. /3 bifarium Nordst. Norges Desm. 1873, p. 31, t. 1,

f. 14 ; Wolle, Desm. U. S. 1884, p. 144, t. 51, f. 24-26 ; De Toni, Syll. Alg.

1889, p. 1157 ; West & G. S. West, Alg. Madag. 1895, p. 73, t. 8, f. 21 ;

Borge, Botan. Notiser, 1913, p. 50; Gronblad, Desm. Keuru, 1920, p. 89.
St. senarium v. alpinum f. tatrica Racib. Norm. Desni. Polon. 1885, p. 32,

t. 12, f. 7.
St. senarium var. bifarium Kaiser, Alg. Traunst. 1914, p. 153.

Semicells with the apical processes emarginate at the
apex, and with an additional series of similar bifid
prominences round the middle part of the semicell, two
between each pair of angles.

Length, without processes, 29-37 (JL ; breadth, without
processes, 30-34 (JL ; breadth of isthmus 10-13(ji.

SCOTLAND. — Falls of Connon, Ross ; near Ballater,
Aberdeen (Roy & Biss.). Plankton of Loch Diracleet,
Harris, Outer Hebrides !

Geogr. Distribution. — Germany. Norway. Sweden.
Finland. Poland. Madagascar. Australia. United States.

STAURASTEUM. 185

PL CLIV, fig. 9 is the form of St. monticulosum frequently
encountered in Britain. It is a form of var. bifarium Xordst.,
but is not identical with Xordstedt's plant, since the lower whorl
of processes is very feebly developed, being represented merely
by pairs of spines. It resembles in some respects var. groen-
landicum Gronbl.

Var. groenlandicum Gronblad. (PI. CLIV. fig. 10.)

St. megatonotum forma Xordst. Desm. Groenl. 1885, p. 11. t. 7, f. 1, 8 ;

West, Alg. W. Ireland, 1892, p. 17.3, t. 23, f. 1.
St. monticulosum Roy & Biss. Scott. Desm. 1893, t. 3, f. 4.
St. monticulosum var. groenlandicum Gronblad, Desm. Keuru. 1920, p. 88,

t. 1, f. 17, 18.

Very similar to var. bifarium Xordst. ; apical and
lower series of prominences, however, considerably
reduced, and provided with one spine each instead of
two ; vertical view with four slight prominences in each
lateral margin apart from the apical processes, the
median pair being, however, larger than the outer two ;
granulation round the angles stronger than in the other
forms.

Length, including processes, 46-50 u. : breadth, in-
cluding processes, 46-50 ^ ; breadth of isthmus, about

SCOTLAND. --Bet ween Bishop's Dam and Clochnaben,
Kincardine.

IRELAND. - -Nacoogarrow Lough, Galway ! Carrantuo-
hill, Kerry !

Geogr. Distribution. — Greenland. Finland.

Var. pulchrum AV. & C4. S. West. (PL CLIV, fig. 12.)

St. monticulosum var. pukhnun West & G. S. West, Alg. X. Ireland, 11)02,
p. 47, t. 2, f. 28; Gronblad, Desm. Keuru, 1920, p. 90.

Smaller and more delicate than the typical form,
processes at the angles much more slender, solid, and
emarginate at their apices, with a pair of slender and
longer spines above each angle.

Length, without spines, 23 [i ; including spines, 29 [JL ;
breadth, without spines, 21 [/. ; including spines, 28 ^ ;
breadth of isthmus 8 [i.

IRELAND. --Lough Gatny, Donegal !

18G BRITISH DESMIDIACE^:.

Gronblad (; Desm. Keuru,' 1920, p. 90) suggests that this alga is
not correctly placed in St. monticulosum — an opinion with which
the writer entirely agrees. It is perhaps nearest amongst British
Desmids to St. aciculiferum (West) Anders., which differs, how-
ever, in several respects. It seerns to have very little affinity with
St. monticulosum Breb.

170. Staurastrum diplacanthum De Not.
(PI. CLVI, fig. 1.)

Staurastrum diplacanthum De Not. Desm. Ital. 1867, p. 49, t. 4, f. 38 ;

Turner, Desm. Notes, 1893, p. 345.

St. vestitum var. diplacanthum Rabenh. Flor. Europ. Alg. 1868, p. 219.
St. monticulosum var. diplacanthum Nordst. in De Toni, Syll. Alg. 1889,

p. 1157.

Cells rather under medium size, slightly longer than
broad, deeply constricted, sinus open and acute ; semi-
cells broadly fusiform, dorsal and ventral margins almost
equally convex ; lateral angles very slightly produced
and terminating in 3 stout spines ; ventral margins with
a stout spine about midway" between the angles and the
isthmus ; dorsal margin with a pair of short distant
processes, bifid at their apex, and with a pair of simple
spines in the middle between them. Vertical view
triangular, sides nearly straight, angles tipped with
3 stout spines ; lateral margins with a pair of bifid
processes, and between these one or two simple spines.
Cell- wall irregularly punctate.

Zygospore unknown.

Cells about 40 \L in diameter.

ENGLAND. — Strensall Common, N. Yorks (W. B.
Turner}.

Geogr. Distribution.- -Italy.

Var. anglicum Turner. (PL CLVI, fig. 2.)

St. diplacanthum var. anglicum W. B. Turn. Desm. Notes, 1893, p. 345, f. 10.

Apex of semicell more convex than in the type,
with a ring of little verrucse ; cell- wall more spiny than
in the typical form.

STAUEASTRUM. 187

Length, without spines, 27-32 IJL ; with spines, 37-41 (i;
breadth, without spines, 28 y. ; with spines, 34 y* ;
breadth of isthmus 9-11 [i.

WALES.- -Trelleck Common, Monmouth (Turn.).

Neither St. diplacanthum nor its var. anglicum are very well
known, and the figures hitherto published have been very poor.
It is almost impossible to get any clear idea of them from the
figures of De Xotaris and Turner.

171. Staurastrum Westii Turner.
(PL CLVI, fig. 4.)

Xftitifijtrinn Westii Turn. Desm. Notes, 1893, p. 345, f. 9.

Each angle of the cell possesses 5 short thick processes
arranged in quincunx, i. e. one in the centre, and one
at each of 4 corners, and in addition there are 3 or 4
spines on the upper margin of each angle (Turn.).

Zygospore unknown.

Length, without spines, 25-28^; including spines,
28-32 [i ; breadth, without spines, 18-21 (ji ; with spines,
23-26 a ; breadth of isthmus 8-10 u.

WALES.- -Llyn Padarn, Carnarvonshire (Turn.).

This species has never been observed since it was described
by Turner, and although his description and figure are somewhat
meagre, it seems to have very well-defined characters. Turner
considered it to be intermediate in form between St. dipla-
canth ion De Xot. and St. spongiosum var. GriffitJisianum.

172. Staurastrum forficulatum Lund.
(PL CLIV, figs. 14-16.)

Staurastrum forficulatum Lund. Desm. Suec. 1871, p. 66, t. 4. f. 5 ; De Toni,
Syll. Alg. 1889, p. 1176 ; Roy & Biss. Scott, Desm. 1893, p. 20 ; West &
G. S. West, Further Contrib. Plankton Scott. Lochs, 1905, p. 505, t. 7,
f. 17; Brit. Freshw. Phytoplankton, 1909, p. 202; Gronblad, Desm.
Keuru, 1920, p. 64.

St. aculeatu/,/ var. bifidum Schmidle, Lappmark Siisswasseralgen, 1898,
p. 55, t. 2, f. 44.

St. forficulatum var. longicorne ibid., p. 55, t. 2, f. 42, 43.

Cells of medium size, about as long as broad, a little
longer than broad, or even up to li times broader than

188 BRITISH DESMIDIACE.E.

long (excluding the spines) ; deeply constricted, sinus
first nearly linear, then opening widely ; semicells sub-
trapeziform or subelliptical, apex truncate with 2
prominent apical emarginate spines or short bind pro-
cesses on the upper margin of each face ; lateral angles
very slightly produced and ending in two stout diverging
spines, which lie in the same vertical plane ; upper and
lower margins of angles with 2 verrucse or tiny spines ;
and with 2 emarginate spines or short spinous processes
projecting from each face. Vertical view triangular or
quadrangular, sides concave with 2 short processes,
emarginate at the apex, projecting from each, and with
2 others just within the margin ; angles very slightly
produced.

Zygospore unknown.

Length, without processes, 40-45 (JL ; with processes,
48-64 [ji ; breadth, without spines, 37-60 ^ ; with spines,
54-95 (ji ; breadth of isthmus 9-1 6 \JL .

SCOTLAND. --Near Buchanty, and near Fowlis Wester,
Perth (Roy & Biss.). Rhiconich, Sutherland (N. C.).
Plankton of Loch Fadaghoda, Lewis, and at Harris,
Outer Hebrides !

Geogr. Distribution. Norway. Sweden. Finland.
Australia. LTnited States.

This rare species is confined in the British Isles to the bogs of
the older palaeozoic and precambrian areas. The biradiate form
is known from S. Harris, Outer Hebrides (see PL CLIV, fig. 16).

173. Staurastrum furcigerum Breb.
(PL CLVI, figs. 7, 8, 11.)

Staurastrum furcigerum Breb. in Menegh. Syiiops. Desm. 1840, p. 22(3 ;
Arch, in Pritch. Infus. 1861, p. 743, t. 3, f. 32, 33 ; Rabenh. Flor. Europ.
Alg. 1868, p. 219 ; Arch, in Quart. Journ. Micr. Sci. 1871, p. 95 ; Xordst.
Norges Desm. 1873, p. 36 ; Kirchn. Alg. Schles. 1878, p. 167 ; Wolle,
Desm. U. S. 1884, p. 146, t. 48, f. 12, 13, t. 52, f. 23, 24 ; Cooke, Brit,
Desm. 1887, p. 178, t. 62, f. 1 ; Hansg. Prodr. Alg. Bohm. 1888, p. 215 ;
Nordst. Bornholm Desm. 1888, p. 207 ; De Toni, Syll. Alg. 1889, p. 1224 ;
Heimerl, Desm. alp. 1891, p. 607 ; West, Alg. W. Ireland, 1892, p. 186 ;
Alg. Engl. Lake Distr. 1892, p. 21 ; Roy & Biss. Scott, Desm. 1893, p. 20 ;
West & G. S. West, Alg. S. England, 1897, p. 496 ; G. S. West, Variation
Desm. 1899, p. 396 ; West &^G. S. West, Alg. X. Ireland, 1902, p. 47 ;

STAUEASTRUM. 189

G. S. West, Brit. Freshw. Alg. 1904, p. 172, f . 65 G ; West & G. S. West,

Brit. Fresh\v. Phytoplankton, 1909, p. 175 ; Kaiser, Alg. Traunstein u.

Chiemgau, I, 1914, p. 152.
? Xanthidium articulatum Corda in Aim. de Carlsbad, 1840, p. 213, t. 5,

f. 35.

Phycastrum furcigerum Kiitz. Phyc. Germ. 1845, p. 138.
Didymodadon furcigerum Ralfs, Brit. Desm. 1848, p. 144, t. 33, f. 12 ; Delp.

Spec. Desm. subalp. 1877, p. 174, t. 14, f. 24-27.
Aster oxaniJiium furcigerum Kiitz. Spec. Alg. 1849. p. 183.
Phycastrum (Amblyactinium) furcigerum Nag. Gatt. einz. Alg. 1849, p. 125.
(Staurastrum) furcigerum Reinsch, Alg. Frank. 1867, p. 170.

Cells large, slightly longer than broad, excluding the
processes, deeply constricted, sinus acute, narrow at
first, then opening more widely ; semicells elliptical,
dorsal and ventral margins almost equally convex,
lateral angles produced into short stout processes, tipped
with two or three sharp spines, apex of semicell with an
upper series of processes, similar or perhaps slightly
shorter than the lower series, and projecting vertically
above them ; processes with concentric series of denti-
culations. Vertical view triangular (or up to 9-radiate),
lateral margins concave, angles somewhat inflated and
then produced into short processes ; apex with a
similar short process in each angle. Semicells with a
single chloroplast and a central pyrenoid.

Zygospore spherical, with numerous spines which are
stouter at the base, and twice dichotomous at the apex.

Length, without processes, 35-48 [Ji ; including pro-
cesses, 50-70 fz ; breadth, including processes, 45-68 JJL ;
breadth of isthmus 13-1 8 pi; diam. zygosp., without
appendages, 39 fz ; Avith appendages, 74 pi.

ENGLAND. Plankton of Crummock Water and
Ennerdale Water, Cumberland ! Westmoreland, and in
the plankton of Brother's Water and Hawes Water !
Lancashire ! (Ralfs). W. and N. Yorks (zygospores from
Pilmoor, N. Yorks) ! Cheshire (Ralfs). Essex ! Burnham
Beeches. Bucks ! Plankton of Bracebridge Pool, Button
Park, War wicks ! Worcs ! Berks (Griffiths). Surrey !
Sussex (Ralfs). Hants ! Dartmoor, Devon (Harris).
Cornwall ! (Marquand).

WALES. — Capel Curig, Carnarvon ! (Cooke & Wills).
Dolgelly, Merioneth (Ralfs). In the plankton !

190 BRITISH DESMIDIACE^E.

SCOTLAND. — General ! zygospores from Dinnet, Aber-
deen (Roy & Biss.). Orkneys ! Not uncommon in the
plankton of Loch Morar, Inverness, Loch Tay, Perth,
and Lochs Fadaghoda and an Tomain, Lewis, Outer
Hebrides !

IRELAND. — Mayo ! Gal way, and in the plankton of
Lough Corrib ! Kerry ! Plankton of Lough Neagh !
Dublin and Wicklow (Arch.).

Geogr. Distribution.- -France. Germany. Switzerland.
Galicia and Austria. Hungary. Servia. Italy. Norway.
Sweden. Denmark. Bornholm. Finland. Poland.
Faeroes. Iceland. Greenland. Siberia. Mongolia.
United States and Alaska. Yukon. Nova Scotia.
Patagonia.

St.furcigemm is a very common species often found in quantity
in pools amongst Myriophyllum, Sphagnum or Utricularia. It
is also a general constituent of the plankton of British lakes.
The upper whorl of processes is liable to variation, and tran-
sitional forms between the type and forma eustephana are not
infrequent (vide infra).

Forma eustephana (Ehr.) Nordst. (PI. CLVII, fig. 1.)

Desmidium eustephanum Ehr, Micr. Leb. S. & N. Amer. 1843, p. 124, t. 4,
f. 23.

Staurastrum eustephanum Ralfs, Brit. Desm. 1848. p. 215 ; Arch, in Pritch.
Infus. 1861, p. 742, t. 2, f. 3 ; Rabenh. Flor. Europ. Alg. 1868, p. 220 ;
Wolle, Desm. U. S. 1884, p. 147, t. 48, f. 9, 10 ; Cooke, Brit, Desm. 1887,
p. 177, t. 62, f. 2 ; West, Desm. Massach. 1889, p. 6, t. 3, f. 18 ; De Toni,
Syll. Alg. 1889, p. 1223, West, Alg. N. Wales, 1890. p. 19 ; Alg. W. Ireland,
1892, p. 185 ; Roy & Biss. Scott. Desm. 1893, p. 19 ; West & G. 8. West,
Alg. S. England, 1897, p. 496 ; Cushman in Bull. Torr. Bot. Club, 1905,
p. 228, t. 8, f. 19.

Stephanoxanthium eustephanum Kiitz. Spec. Alg. 1849, p. 184.

Staurastrum furcigerum forma eustephana Nordst. Bornholm Desm. 1888,
p. 207 ; G. S. West, Variation Desm. 1899, p. 396.

This form only differs from typical St. furcigerum in
that the upper whorl of processes is doubled, consisting
of 6 instead of the usual whorl of 3 in the ordinary
triradiate specimen. The lower processes are quite
normal.

Length, without processes, 40 [JL ; including processes,
58 pi ; breadth, including processes, 57 (JL ; breadth of
isthmus 12 i.

STAURASTRUM. 191

ENGLAND.- -Bowness and Loughrigg, Westmoreland !
New Forest, Hants ! Dartmoor, Devon (Harris). In
the plankton !

WALES. — Capel Curig and Llyn Ogwen, Carnarvon-
shire ! In the plankton !

SCOTLAND. — Spital of Glen Shee, Perth !

IRELAND.- -In lakes, Clifden to Roundstone, and
Ballynahinch, Galway ! Glen Caragh, Kerry !

Geogr. Distribution. — Germany. New Zealand. United
States.

The lower whorl of processes in forma eustephana do not seem,
at any rate in British specimens, to have so many or as acute
denticulations as in the type form. Furthermore the margins
of the upper whorl of processes seem to be practically smooth.

It has been pointed out by G. S. West (' Variation Desm.' 1899,
p. 396) that this form was correctly placed by Nordstedt as a
form of St. furcigerum, since specimens have been observed in
which one semicell was typical, and the other of the form
eustephanum. Further, the zygospore figured on PL CLVI,
fig. 8 shows the conjugation of a typical specimen of St. furci-
gerum with one of forma eustephana. This is an additional proof
that the two forms are really the same species. Cushman
(; Bull. Torr. Bot. Club,' 1905, t. 8, f. 19) also figures the zygospore
of forma eustephana. His specimen shows rather more compli-
cated appendages than the example figured above.

Forma armigera (Breb.) Nordst. (PI. CLVI, fig. 10.)

Stan rast rum armigerum Breb. Liste Desm. 1856, p. 136, t. 1, f. 22 ; Roy &

Biss. Scott. Desm. 1893, p. 17, t. 3, f. 12.
St. pseudof urc iger um Reinsch, Spec. Gen. Alg. 1867, p. 20, t. 4 C, f. I ; Alg.

Frank. 1867, p. 169, t. 11, f. 2 ; Wills, Alg. X. Wales, 1881, t, 5, f. 10 ;

Cooke, Brit. Desm. 1887, p. 147, t. 61, f. 4 ; Hansgirg, Prodr. Alg. Bohm.

1888, p. 215.
St. furcigerum forma armigera Nordst. Desm. Boniholm 1888, p. 207 ;

West & G. S. West, Alga-fl. Yorks. 1902, p. 98 ; Further Contrib. Plank-
ton Scott. Lochs, 1905, p. 487.
St. furcatum var. armigerum West, Alg. X. Wales, 1890, p. 16; Alg. Engl.

Lake Distr. 1892; p. 19 ; Alg. W. Ireland, 1892, p. 174.

Cells in form similar to the type, but with the lower
whorl of processes somewhat longer than usual, and
with an apical whorl of 6 accessory processes (in the
usual triradiate form). All the processes are consider-

192 BRITISH DESMIDIACE^E.

ably longer than usual, and their margins are crenulate
rather than denticulate.

Zygospore spherical with numerous spines, broad at
the base, and tapering to a fine, slightly bifid apex (Roy).

Length, without processes, 45 (JL ; including the pro-
cesses, 80 pi ; breadth, without processes, about 35 [JL ;
including processes, 70 [JL ; breadth of isthmus 15 (JL.

ENGLAND. — Cumberland ! Lancashire ! N. Yorks (W.
B. Turn.}. Surrey ! Hants ! Devon ! (Harris).

WALES. --Dolbadarn Castle !, Llyn Padarn !, and Capel
Curig ! (Cooke & Wills), Carnarvonshire.

SCOTLAND.- -Inverness, Aberdeen, Kincardine, Forfar,
Perth, Stirling and Arran ; zygospores from Heughhead,
near Aboyne, Aberdeen (Roy & Biss.). Sutherland and
in the plankton of Loch nan Cuinne ! Plankton of Loch
Luichart, Ross !, Loch Shiel, Inverness !, and Loch Tay,
Perth !

IRELAND. — Ballynahinch, Galway ! Lower lake of
Killarney, Kerry ! Adrigole, Cork ! Dublin and Wick-
low (Arch.).

Geogr. Distribution.- -France. Germany. Galicia in
Austria. Turkey. Norway. Sweden. Finland. Poland.
India. Australia. New Zealand. United States.

Var. reductum W. & G. S. West. (PL CLVI, fig. 9.)

St.furcigerum\a.T. reductum West & G. S. West, Compar. Study Irish Lakes,
1906, p. 104, t, 11, f. 12.

Processes very much shorter than in the type, upper
processes extremely short ; vertical view triangular,
sides nearly straight or very slightly convex.

Length 43 (Ji ; breadth, including processes, 54 ^ ;
breadth of isthmus 21^.

ENGLAND.- -Dartmoor, Devon (Harris).

IRELAND.- -Plankton of Lough Corrib, Galway !

This variety is distinguished chiefly by the great reduction of
the superior processes. In one semicell they were observed to
be suppressed entirely.

STAURASTRUM. 193

174. Staurastrum Arctiscon (Ehr.) Lund.
(PL CLVII, fig. 5.)

Xa nth id turn No 2 Bailey, Amer. Bac. 1841, p. 291, t. 1, f. 15.

Xanthidium Arctiscon Ehr. Micr. Leb. S. u. N. Amer. 1843, p. 138 ; Ralfs,

Brit. Desm. 1848, p. 212 ; Rabenh. Flor. Europ. Alg. 1868, p. 224 ;

Kirchn. Alg. Schles. 1878, p. 155.
Staurastrum Arctiscon Lund. Desm. Suec. 1871, p. 70, t. 4, f. 8 ; Wills in

Midi. Nat. 1881, t. 4, f . 5 ; Wolle, Desm. U. S. 1884, p. 148, t. 47, f. 9, 10 ;

Cooke, Brit. Desm. 1887, p. 179, t. 63, f. 1 ; De Toni, Syll. Alg. 1889,

p. 1226 ; Roy & Biss. Scott. Desm. 1893, p. 17 ; West & G. S. West,

.Some N. Amer. Desm. 1896, p. 269 ; Alg. N. Ireland, 1902, p. 47 ; Scott.

Freshw. Plankton, I, 1903, p. 551 ; Further Contrib. Plankton Scott.

Lochs, 1905, p. 487 ; Comp. Study Plankt. Irish Lakes, 1906, p. 87 ;

Cushman in Bull. Torr. Bot. Club, 1907, p. 615 ; West & G. S. West,

Phytopl. Engl. Lake Distr. 1909, p. 289 ; Brit. Freshw. Phytoplankton,

1909, p. 174.
St. munitum Wood, Freshw. Alg. N. Amer. 1873, p. 154, t. 13, f. 13.

Cells large, about \\ times longer than broad, exclud-
ing the processes, constriction fairly deep ; sinus nearly
rectangular with subacute apex ; semicells broadly
elliptical or subspherical. provided with 2 whorls of
processes ; lower whorl consisting of 9 processes, nearly
horizontal, 5 of which are visible in the front view;
upper whorl of 6 processes, ascending obliquely; pro-
cesses nearly as long as the body of the semicell is
broad, tipped with 3 spines, and with 2-7 series of

denticulations ; body of cell smooth. Vertical view

j

nearly circular, with a marginal series of 9 processes,
and an apical series of 6 shorter processes. Chloroplast
axile with a central pyrenoid, and a lobe stretching into
the base of each process.

Zygospore unknown.

Length, without processes, 66-96 fx ; with processes,
100-1 55 \i ; breadth, without processes, 46-68 (JL ; with
processes, 92-160 \L ; breadth of isthmus 24-33 \L.

ENGLAND.- -Plankton of Crummock Water and Enner-
dale Water, Cumberland ! Plankton of Brother's Water,
Grasmere and Easedale Tarn, Westmoreland !

WALES. — Capel Curig ! (Cooke & Wills] and Llyn
Ogwen !, Carnarvonshire. In the plankton.

SCOTLAND.- -Birsemore Loch and Dalbagie, Aberdeen ;
Tobermory in Mull, Argyle (Roy & Biss.). Plankton of

VOL. v. 13

194 BRITISH DESMIDIACE^:.

Lochs Shin, Ghriama and nan Cuinne, Sutherland !, Loch
Shiel, Inverness !, Loch Tay, Perth ! and Loch Doon,
Ayr ! ; of Loch Fadaghoda, Lewis, Loch Laxadale,
Harris, and Loch nan Eun, N. Uist, Outer Hebrides !

IRELAND. — Near Lough Magrath, Donegal ! Bally-
nahinch and lakes east of Lough Bofin, Galway ! Plank-
ton of Galway and Kerry !

Geogr. Distribution. — Germany. Norway. Sweden.
Finmark. Finland. United States. Alaska. Brazil (var.).

This beautiful species is only found in the western parts of
the British Isles, and is most abundant in plankton. The length
of the processes tends to vary somewhat, but their arrangement
is constant.

175. Staurastrum sexangulare (Bulnh.) Lund.
(PI. CLVII, figs. 2, 3.)

Didyrnodadon sexangulare Bulnh. in Hedwigia, 1861, p. 51, t. 9 A, f. 1.

Staurastrum sexangulare Lund. Desm. Suec. 1871, p. 71, t. 4, f. 9 ; Arch,
in Grevillea, 1881, p. 30 ; Cooke, Brit, Desm. 1887, p. 178, t. 62, f. 3,
t. 64, f. 4 ; De Toni, Syll. Alg. 1889, p. 1224 ; Borge; Bidr. Sibir. Chlor.
1891, p. 10 ; Roy & Biss. Scott. Desm. 1893, p. 25 ; Comere, Desm. de
France, 1901, p. 159, t. 11, f. 6 ; West & G. S. West, Alg. Ceylon, 1902,
p. 181 ; Scott. Freshw. Plankton, 1903, p. 550 ; British Freshw. Phyto-
plankton, 1909, p. 202.

St. furcato-stellatum Reinsch, Contrib. Alg. et Fung. 1875, p. 85, t. 16, f. 1.

Didymodadon Stella Mask. N. Zeal. Desm. 1881, p. 308, t. 11, f. 9.

Staurastrum Stella Mask. N. Zeal. Desm. Add. 1883, p. 254.

Cells of medium or large size, usually a little longer
than broad, excluding the processes, deeply constricted,
sinus acute, open ; semicells elliptical or subfusiform,
apex slightly convex, lower margin slightly ventricose,
produced at the lateral angles, which are deeply cleft,
to form an upper and a lower process ; semicells with a
corresponding upper and lower Avhorl of processes
stretching horizontally across the semicell (about 4 or
5 pairs visible) ; processes of lower whorl nearly hori-
zontal or very slightly converging, those of upper whorl
diverging ; processes tipped with 3 or 4 spines and with
2 or 3 series of denticulations. Vertical view usually
5-7- (4-8-) radiate ; lateral margins deeply concave, with
a pair of flattened granules just within ; angles pro-
duced to form long tapering processes, with an upper

STAUEASTRUM. 195

process arising from the base of each lower process ;
processes of upper and lower whorls rarely exactly
superimposed, the upper whorl being twisted very
slightly in one direction. Chloroplast axile with a
pyrenoid in each angle and a pair of lobes stretching
into the base of each process.

Zygospore unknown.

Length, without processes, 44-60 [j, ; with processes,
74-1 00 pi ; breadth, without processes, about 43-54 y. ;
with processes, 84-1 20 [/. ; breadth of isthmus 13-22 ji.

ENGLAND.- -Plankton of Ennerdale Water, Cumber-
land !

WALES. — Capel Ctirig, Carnarvonshire! (Cooke &
Wills). In the plankton !

SCOTLAND. --Near Brin, Inverness (Roy & Biss.)
Rhiconich and in the plankton of Lochs nan Cuinne
and Shin, Sutherland ! Plankton of Loch near Cearna-
bahl and Lochs an Sgath, an Tomain, Langabhat,
Stranabhat and Fadaghoda, Lewis, Outer Hebrides !

IRELAND. — Connemara, Gal way (Arch.). Plankton of
Galway and Kerry !

Geogr. Distribution.- -France. Germany. Norway.
Sweden. Finland. Siberia. Central China. Japan.
India. Ceylon. Burma. Singapore. Java. Australia.
New Zealand.

This species differs from St. furcigerum Breb., which is the
only other British, species having a pair of vertically placed
processes at each angle, in the different shape of its semicells,
its more open sinus, and in the distinctly lateral insertion of all
its considerably longer processes. It is not an uncommon
species in the plankton of some lakes in the western parts of the
British Isles, but is otherwise very rare.

Var. supernumerarium W. & G. S. West. (PL CLVII,

fig. 4.)

St. sexangidare var. supernumerarium West & G. S. West, Scott. Freshw.
Plankton, I, 1903, p. 551, t. 18, f. 8.

This variety has an extra small process placed between
each upper and lower process.

196 BRITISH DESMIDIACE^.

Length, without processes, 51 [x ; including processes,
65 pi ; breadth, without processes, about 42-46 (JL ; in-
cluding processes, 84*5-90 (JL ; breadth of isthmus 12 (JL.

SCOTLAND.- -Plankton of Loch Shin, Sutherland !

SPECIES TO BE ENQUIRED INTO.

STAURASTRUM MESOLEIUM Arch, in 'Ann. Mag. Nat. Hist.' v.
13, ser. 5, no. 74, 1884, p. 145 ; Cooke, ' Brit. Desm.' 1887, p. 190 ;
Eoy & Biss. ' Scott. Desm.' 1893, p. 190. "About medium sized,
triangular in end view, in front view the angles a little produced,
slightly spinulose. Resembling St. oligacanthum of Nordstedt,
but not of de Brebisson." Size ?

Hob. — Ireland : Gallery Bog, Connemara. Scotland : Scots-
ton Moor.

STAURASTRUM REPANDUM (Perty) Rabenh. 'Flor. Eur. Alg.'
1868, p. 221 ; De Toni, 'Syll. Alg.' 1889, p. 1143. Phycastrum
(P achy actinium) repandum Perty, ' Kleinst. Lebensf.' 1852, p. 210,
t. 16, f. 26. " In front view •£$"' long, each semicell prolonged
at the lateral angles into sharp points ; dorsal margin sloping
gently downwards ; vertical view triangular, angles and sides
almost equal, angles drawn out into sharp points. Breadth,
including the acute points, oV".

Hob. — Scotland : Glen Callator, Aberdeen (Roy & Biss.).
Switzerland.

STAURASTRUM STRENSALLENSE Turn. 'Alg. E. India,' 1893,
p. 113, t. 17, f. 1. Of medium size, almost as long as broad;
sernicells depressed ovate, dorsal margin gently convex, ventral
margin rounded and inflated, angles rounded; cell- wall covered
densely with spines, disposed in 9 or 10 transverse series, that
part near the isthmus being, however, smooth ; sinus acute,
opening widely. In vertical view triangular, sides slightly
concave, angles broadly rounded. Length 65 /m ; breadth 63 ^ ;.
breadth of isthmus 21 /u ; length of spines 3-6 /u.

Hob. — England : Strensall Common, Yorkshire.

STAURASTRUM TRACHYNOTUM West, 'Alg. W. Ireland,' 1892,
p. 176. S. saxonicwn Reinsch, ' Spec. Gen. Alg.' 1867, p. 127,
t. 24 C, f. 1-4. Var. ANNULATUM West, 'Alg. W. Ireland,' 1892,
p. 176, t. 24, f. 16. Cells slightly longer than broad, deeply

COSMOCLADIUM. 197

constricted, sinus almost rectangular ; semicells subfusiform,
margins of semicell and angles provided with, simple or emarginate
spines ; with a circle of large granules round the base of the
semicell.

Hob. — Ireland : Carrantuohill, Cork.

[Both St. tracliynotum West., and its var. annulatum are probably
forms of St. aculeatum (Ehr.) MenegJi.]

EXCLUDED SPECIES.

STAURASTRUM OSTEONUM West, ;Alg. X. Wales,' 1890, p. 293,
t. 5, f. 7.

Genus 19. COSMOCLADIUM Breb. 1856.

Breb. Liste Desm. 1856, p. 133.

De Bary, Conj. 1858, p. 77.

Arch, in Pritch. Infus. 1861, p. 752.

Arch, in Quart. Journ. Micr. Sci. vol. 7, 1867, p. 299.

Rabenh. Flor. Europ. Alg. 1868, p. 53.

Kirchn. Alg. Schles. 1878, p. 105.

Cooke, Brit. Desm. 1887, p. 78.

De Toni, Syll. Alg. 1889, p. 804.

\Ville, in Engler. Xaturl. Pflanzenfam. 1890, p. 11.

Comere, Desm. de France, 1901, p. 180.

G. S. West, Brit. Freshw. Alg. 1904, p. 173.

Cells minute, constricted at the middle, usually com-

i/

pressed and symmetrical in 3 planes at right angles to
each other; semicells subpyramidate, elliptic or sub-
reniform, cell- wall smooth ; chloroplasts axile, usually
one in each semicell, with a central pyrenoid and 4
projecting lobes; rarely with a single chloroplast in each
cell, the pyrenoid occupying a central position. Indi-
vidual cells indistinguishable from small species of
Cosmarium, united, however, to form colonies of greater
or smaller size (but never macroscopic), by means of
gelatinous threads, single or double, secreted through
pores in the cell membrane in the vicinity of the sinus.
Colonies branched in an irregular fashion, usually free

d? •/

floating but sometimes of tree-like habit and attached

o

to other algae.

Zygospores only known in one or two species, more or

198 BRITISH DESMIDIACEJE.

less spherical or sometimes angular, with short stout
spines or obtuse protuberances.

The genus Cosmodadium is closely related to Cosmarium, from
which, undoubtedly, it was originally derived. Its chief distinc-
tion from that genus is that the cells are joined together by means
of slender gelatinous stalks, which are attached in the vicinity
of the sinus. In this wav, more or less branched colonies of

»/ •

varying size and shape are formed. It has been shown by Dr.
Lutkemuller that the connecting gelatinous threads are secreted
by special groups of pores situated near the base of the semicell..
There may be single strands, or sometimes a pair of parallel
gelatinous filaments joins the cells, depending on the number
of pore groups present. In C. constrictum each semicell possesses
one series of pores at its base, and here a single strand connects
the cells, but in C. Saxonicum there is a group of these special
pores on each side of the isthmus in each semicell, and in conse-
quence the connecting strands are paired. In some of the
other species it is impossible to say definitely whether the con-
necting strands are single or double, since they have not been
sufficiently investigated on this point, and because the strands
are so delicate that it is not easy to decide the question. The
entire colony is, in addition, sometimes immersed in a delicate
mass of jelly.

The genus Cosmodadium was much confused in earlier times
with the Protococcales genus Dictyosphcerium. It is most
readily distinguished from this genus, however, not only by its
constricted cells, but also by the fact that the cells are placed
at various points, not merely at the periphery of the colony.

There are 5 British species of the genus, all of which are very
rare. They are very minute and inconspicuous, and are very
easily overlooked.

1. Cosmodadium constrictum Arch.
(PI. CLVIII, figs. 1-3.)

Dictyosphcerium sp. Arch, in Quart. Journ. Micr. Sci. 1865, p. 127.

D. constrictum Arch. ibid. 1867, p. 299 : ibid. 1872, p. 422.

Cosmodadium constrictum Arch. ibid. 1875, p. 415 ; Josh, in Journ. Bot.
1883, p. 292 ; Cooke, Brit. Desm. 1887, p. 79 ; De Toni, Syll. Alg. 1889,
p. 805 ; Roy & Biss. Scott. Desm. 1893. p. 254, t. 2, f. 7 ; Liitkem. Zell-
membr. Desm. 1902, p. 359, t. 18, f. 31-33 : West & G. 8. West, Alga-fl.
Yorks. 1902, p. 95 ; G. S. West, Brit, Fresrtnv. Alg. 1904, p. 173, f. 66 A.

Cells very small, rather more than 1| times longer

COSMOCLADIUM. 199

than broad, subcylindrical, constriction extremely slight,
semicells subpyramidate, narrowing slightly towards the
apex, with gently rounded outlines ; end view circular.
Chloroplast axile, only one in each cell, with a central
pyrenoid (occasionally 2 are present), and 4 radiating
parietal lobes. Cells united by means of gelatinous fila-
ments to form branched colonies of an irregular shape ;
cells not only at the ends of the strands but arranged
distantly at intervals along them.

Zygospore spherical, with many short, stout, acute
spines.

Length of cell 16-20 (x ; breadth = thickness = 10-12 y. ;
breadth of isthmus 8 "5-9^; diam. zygosp., without
spines, 17-20 pi ; with spines, 30^.

ENGLAND.- -Pilmoor, near Thirsk, N. Yorks ! Plank-
ton of Bracebridge Pool, Sutton Park, Warwickshire !
Dartmoor, Devon (Harris).

SCOTLAND. --" Old Road : and Heughhead, near
Aboyne, Aberdeen; Dalbrake in Strachan, Kincardine;
Buchanty, Perth (Roy & Biss.).

IRELAND.- -Dublin and Wicklow (Arch.).

Geogr. Distribution. — Sweden. Finland. United States.

C. constrictum is an alga which is frequently overlooked
because the cells are small and are distantly arranged, so that
the colonies are not dense. It is usually found in bogs, and
although not frequent, is one of the commonest species of the
rare genus Cosmocladium. The specimens found in the plankton
of Bracebridge Pool consisted almost entirely of isolated cells.

It has been shown bv Dr. Lutkemuller that in the cells of this

«/

species there are two series of minute pores, arranged closely
together on either side of the isthmus. They are only present
on one side of the cell — that side which is directed towards the
centre of the colony, and extend about frds of the distance
across the face of the cell when examined in front view. They
are only rendered visible by special staining methods. These pores
give rise to the gelatinous strands, which, extending from the
isthmus of one cell to the next, unite the cells together.

200 BRITISH DKSMIDIACE.E.

2. Cosmocladium perissum Eoy and Biss.
(PL CLVIII, figs. 4-7.)

Cosmocladium perissum Roy & Biss. Scott. Desm. 1893, p. 62, t. 2, f. 14;
G. S. West, Brit. Freshw. Alg. 1904, p. 173, f. 66 C.

Cells minute, flattened, nearly as broad as long, con-
striction fairly deep and somewhat obtuse, opening
widely ; apex slightly concave, sides broadly rounded ;
cell-wall very pellucid and sometimes brownish in
colour ; end view elliptical ; cells forming free colonies.

Zygospore large in proportion to the size of the cells,
extremely irregular in shape, with several irregular and
blunt spiny protuberances, reddish brown in colour.

Length 12-1 3 pi; breadth 10-12^; thickness 6 pt ;
diam. zygospore 15-20 pi (-27 j* ; West).

SCOTLAND. — Aboyne, Aberdeen ; Cammie in Strachan,
Kincardine (Roy & Biss.). Clova Mts., Forfar !

This species never forms very large colonies, and more than
4 cells are scarcely ever found together. The cells occur in a
simple row, loosely joined by very delicate gelatinous threads.
The semicells have only two jelly-secreting pores each, one on
either side of the isthmus, whereas both Cosmocladium constrictum
and C. Saxonicum have quite a well-developed series of pores.
This very slight development of secreting pores is responsible
for the extreme delicacy of the connecting strands, and the small
size of the colonies in C. perissum as compared with the two above-
mentioned species.

3. Cosmocladium pulchellum Breb.
(PL CLVIII, figs. 11, 12.)

Cosmocladium pulchellum Breb. Liste Desm. 1856, p. 133, t. 1, f. 20; De
Bary, Conj. 1858, p. 77; Ueber Cosmocladium, 1865. p. 329; Rabenh.
Flor. Europ. Alg. 1868, p. 54 ; Kirchn. Alg. Sehles. 1878, p. 10f> ; De
Toni, Syll. Alg. 1889, p. 804; Roy & Biss. Scott. Desm. 1893, p. 62;
Comere, Desm. de France, 1901. p. 180, t, 15, f. 15; G. S. West, Brit.
Freshw. Alg. 1904, p. 173, f. 66 B.

Cells small, somewhat longer than broad, deeply
constricted, sinus narrow but opening more widely;
semicells elliptical or subreniform; vertical view ellip-

COSMOCLADIUM. 201

tical. Chloroplasts axile, with a pyrenoid in the centre
of each semicell. Cells united into colonies by means
of gelatinous threads, sometimes with a tree-like habit
and attached to other larger filamentous algae (according
to de Brebisson).

Zygospore unknown.

Length of cells 12-24^ ; breadth 11-16^ ; thickness
6-7 u ; breadth of isthmus 4-4'5 a.

SCOTLAND. — Aboyne, Aberdeen ; Bogandreep in Glen
Dye, Kincardine; Clova Tableland, Forfar (Roy & Biss.).
Rhiconich, Sutherland ! Near Tarbert, Harris, Outer
Hebrides !

Geogr. Distribution- -France. Germany. United
States.

4. Cosmocladium pusillum Hilse.
(PI. CLYIIL figs. 8-10.)

Cosmocladium pusillum Hilse in Bericht. d. Schles. Ges. 18(55. p. 117; in
Rabenh. Alg. Eur. 1867, no. 1963; Rabenh. Flor. Europ. Alg. 1868,
p. 54 : Kirchn. Alg. Schles. 1878. p. 105 ; De Toni, Syll. Alg. 1889, p. 805.

Cosmocladium subramosum Schmidle, Chlorophy.-H. Torfstiohe Virnheim,
1894. p. 49, t. 7, f. 8 ; West & G. S. West, All'. X. Ireland, 1902, p. 42,
t. 2, f. 13, 14.

Cells small, up to 1^ times longer than broad, deeply
constricted, sinus linear for most of its length, then

o

opening more widely ; semicells oblong-elliptic, apex
somewhat flattened, sides broadly rounded ; in end-view
elliptical ; chloroplasts axile, with a pyrenoid in the
centre of each semicell. Colonies usually small, rarely
consisting of more than 8 cells, only very slightly or
not at all branched, free-floating ; cells mostly with
their broad surface perpendicular to the direction of the
connecting gelatinous threads ; colonies sometimes en-
veloped in a very thin, scarcely- visible mucus.

Zygospore unknown.

Length of cell ll-12[j. ; breadth 11 -12u ; thickness
5-6 [JL ; breadth of isthmus 2-3 pt.

IRELAND.- -Lough Anna, Donegal ! Rare in the plank-
ton of Gal way.

Geogr. Distribution. — Germany. Finland.

202 BRITISH DESMIDIACE/E.

C. pusillum Hilse is one of the smallest species of the genusr
and is very rare. It is uncertain whether the delicate connecting
strands between the cells are single or double. C. pusillum is
distinguished from C. perissum and C. pulchellum by the special
characters of its colonies, and by its cells equal in length to their
breadth, with oblong semicells and deep, linear sinus.

That C. subramosum Schmidle is synonymous with C. pusillum
Hilse was pointed out by Dr. Liitkemuller in a letter to the late
Professor G. S. West in 1912. Dr. Liitkemuller had carefully
examined the original specimens of Hilse in Kabenhorst's 'Alg.
Exs.' no. 1963, and compared them with preserved material of
C. subramosum identified by Schmidle. He came to the con-
clusion that the two were identical both in the form of their cells
and the character of the colonies.

5. Cosmocladium Saxonicum De Bary.
(PL CLVIII, figs. 13-16.)

Cosmocladium Saxonicum De Barv, Cosmocladium, 1865, pp. 321-9, t. 4,
f. 1-3 ; Arch, in Quart. Journ. Micr. Sci. vol. 7, 1867, p. 298 ; Pxabenh.
Flor. Eur. Alg. 1868, p. 54 ; Arch, in Quart, Journ. Micr. Sci. 1874, p. 212 ;
Cooke, Brit. Desm. 1887, p. 78, t. 35, f. 16; De Toni, Syll. Alg. 1889,
p. 804 ; Roy & Biss. Scott. Desm. 1893, p. 63 ; ? West & G. S. West, Alg.
S. England,' 1897, p. 492 ; Schroder, Cosm. Saxomcum, 1900, p. 15. t. 1 ;.
Ltitkem. Zellm. Desm. 1902, p. 359, t. 18, f. 34-36 : West & G. S. West,
Notes Alg. III. 1903, p. 10 ; Comp. Study Plankt. Irish Lakes, 1906,
p. 102 ; Kofoid, Plankt. 111. River, 1908, p. 61 ; West & G. S. West,.
Brit, Freshw. Phytoplankton, 1909, p. 168.

Cells larger than in any other British species of the
genus, about li times longer than broad, deeply con-
stricted, sinus acute angled, opening widely; semicells
subelliptic-reniform, dorsal margin much more convex:
than the ventral ; in vertical view elliptic ; chloroplasts
axile, with one pyrenoid in each semicell, and 4 lobes
projecting from the central mass towards the cell- wall.
Cells united by 2 parallel gelatinous filaments into
colonies of varying size, consisting only of 2 or 3 cells,
or up to 90 in a single colony ; colonies free-floating, and
sometimes immersed in a delicate jelly ; cells usually
parallel to each other, and with their broad faces
perpendicular to the direction of the strings, so that
normally their side view is presented to the observer.

OOCARDIUM. 203

Zygospore recorded by Gronblad (' Desm. Keuru,' 1920,
p. 82), but without description or figure.

Length 22-27 pi ; breadth 18-20 p ; thickness 12-15 EJL;
breadth of isthmus 3 '5-7 pi.

ENGLAND.--? Thursley Common, Surrey (identified
with doubt) !

WALES. — Capel Curig ! arid pool near Llyn Elsie,
Bettws-y-coed (Arch.), Carnarvonshire ! In the plankton !

SCOTLAND. --Dalbrake and Heughhead in Sfcrachan,
Kincardine (Roy & Biss.). Near Tarbert, Harris, Outer
Hebrides !

IRELAND.- -Dublin ; Carrick Mts., Wicklow ; Callery
Bog (Arch.). In the plankton !

Geoqr. Distribution. — Germany. Austria. Norway.

U «/ i

Finland. United States.

Both Schroder and Liitkemliller have carefully investigated
this species, and found that each cell possesses 4 special groups
of pores near the isthmus which are responsible for the secretion
of the gelatinous connecting threads (cf. PL CLVIII, fig. 16).
These pores are seen in the basal view of the semicell lying at
opposite poles of the aperture which represents the isthmus. The
connecting threads appear early during cell division and are seen
as delicate strands stretching between the older semicells,
becoming longer and stronger as the cells reach maturity. They
very often show somewhat fusiform thickenings between each
pair of cells, the significance of which is not properly understood.

Genus 20. OOCARDIUM Nag. 1849.

Nag. Gatt. einz. Alg. 1849, p. 74.

Kiitz. Spec. Alg. 1849, p. 196.

Kiitz. Tab. Phye. II, 1850, t. 83, f. 5.

Pxabenh. Flor. Eur. Alg. 1868, pp. 13, 53.

De Toni, Syll. Alg. 1889, p. 658.

Senn in Botan. Zeitung, 1899, p. 81.

G. S. West, Brit. Freshw. Alg. 1904, p. 174.

Cells essentially of the Cosmarium type, small, de-
pressed, considerably broader than long, very slightly
constricted, unequally flattened on the two sides, so
that the cells are only symmetrical in 2 planes at right
angles instead of 3, as is general in Cosmarium and the

204 BRITISH DESMIDIACE^.

allied genera ; cell-wall smooth ; chloroplasts axile
with a central pyrenoid in each semicell ; cells embedded
in the ultimate ends of a radiating and branched system
of gelatinous strands, the latter being encrusted with
lime, aggregated in colonies 1-2 mm. in diameter.

Zygospore angular, writh several mamillate projec-
tions.

This genus is closely related to Cosmarium and Cosmodaditim.
From the latter genus it is distinguished primarily by the fact
that its cells are produced only at the periphery of the gelatinous
and usually lime- encrusted macroscopic colony. The more
asymmetrical form of the cells in Oocardium is of no great impor-
tance, since it has been shown by Senn that this is an effect of
the deposition of lime, and that if cultures are kept in lime-free
water, so that lime cannot be deposited, and the colonies simply
remain gelatinous, the cells become more symmetrical.

The genus has been alternately placed in the Palmellacese
(Protococcales) or the Desmidiacese by various authors since it
was described by Nageli. There is no doubt, however, as to its
real affinities. The structure of its cell-wall and the nature of
its cell-division are sufficient to prove that it is a true Desmid.
The final proof of its systematic position has recently been
brought forward by the present writer, who was fortunate
enough to find the zygospores in some collections of algse from
India. There is only one known species of the genus.

1. Oocardium stratum Nag.
(PI. CLIX, figs. 1-8 ; PL CLXVII, figs. 1-4.)

Oocardium stratum Nag. Gatt. einz. Alg. 1849, p. 75, t. 3 A ; Kiitz. Spc.
Alg. 1849, p. 196 ; Tab. Phycolog. 1850, v. 2, t. 83, f. 5 ; Rabenh. Flor.
Eur. Alg. 1868, p. 53 ; De Toni, Syll. Alg. 1889, p. 658 ; Senn, Colonie-
bildende Alg. 1899, p. 81; Oocardium stratum, etc. 1899, p. 221; W. &
G. S. West, Alga-fl. Yorks. 1902, p. 130 ; Liitkem. Zellmem. Desm. 1902,
p. 360, t. 18, f. 37, 38, t. 19, f. 4-6 ; G. S. West, Brit. Freshw. Alg. 1904,
p. 174, f. 6(1, D-F ; Virieux, Alg. et Peridin. 1913, p. 4.

Colonies small, 1-2 mm. in diameter, hemispherical
or longer column-like structures, gregarious, bright
green. Cells small, about \\ times broader than long-
in the front view (i. e. that in which the largest face is
visible and the constriction horizontal), depressed, very

OOCARDIUM. 205

slightly constricted, unequally depressed on the two
sides so that the cell is longer on the one side than the
other ; lateral view oblong-elliptic, slightly longer than
broad, with the faintest indication of a constriction ;
vertical view oblong-elliptic, ratio of axes 1 : 1|. Chloro-
plasts axile, one in each semicell, concentrated in the
front view towards the broader side of the cell, with a
central pyrenoid in each chloroplast. Cells embedded in
the ultimate ends of branched gelatinous strings, each
strand of which is surrounded by a hollow cvlinder of

«/ J

lime, from the apex of which the cell just protrudes; cell
inserted in the tube so that the broader end of the cell,
containing the greater part of the chloroplast, is directed
towards the periphery, and the narrow end within the
tube, with the constriction in a vertical direction.

Zygospores rectangular or polyhedral, , with several
large mamillate projections ; membrane smooth.

Length 13-20 a ; breadth, 18-24fi, ; thickness 17 a ;
cliam. zygosp. (of var. minor with cells 7-8 [i long,
12-14 pi wide) 15-20 a.

ENGLAND. — Gordale and Austwick, W. Yorks !

IRELAND.- -Leinster Province (Adams).

Geogr. Distribution.- -France. Germany. Austria.
India (form).

This remarkable Desmid is very rare and only occurs in
streams in limestone districts, usually in waterfalls or in swiftly
flowing water, where it forms a calcareous deposit on rocks,
stones or even twigs.

Its preference for situations in which an abundance of lime is
available is rather peculiar, since the majority of Desmids strictly
avoid such localities.

The gelatinous threads, containing at their extremity the algal
cells, become enclosed in cylinders of lime by the metabolic
activities of the living cell, whereby carbon dioxide is with-
drawn by the algae for the purpose of photosynthesis from
the water in which much calcium carbonate is also dissolved.
As a result of the removal of this carbon dioxide, the calcium
carbonate is no longer as soluble as before, and consequently
comes out of solution and is deposited round the algal cells.
In order that it shall not thus be completely encased in lime, the

206 BRITISH DESMIDIACE.E.

cell begins actively to secrete mucilage through the special
pore organs of its cell-wall, by which means the thin layer of
lime is ruptured, and the cell is lifted bodily in the mucilage out
of the stony mass. In this way the tiny cylinders of lime are
continually increasing in length, and the cells, by secreting
mucilage, are raised higher and higher at the same time.

Cell-division proceeds as in ordinary Desmids, and the two
daughter-cells secrete, when fully developed, their own gela-
tinous stalks, which in time become encrusted with lime. Thus
as the cells increase in number the lime cylinders also increase in
number, so that there is always a single cell at the top of one lime
tube. A layer of lime as much as '5 cm. thick may be deposited
in a single year.

Genus 21. SPHJEROZOSMA Corda, 1835.

Corda in Aim. de Carlsbad, 1835, p. 207 ; ibid. 1840, p. 205.

Ralfs in Ann. Mag. Nat. Hist, 1845, vol. 16, p. 13.

Hass. Brit. Freshw. Alg. 1845, p. 348.

Ralfs, Brit, Desm. 1848. p. 65.

De Bary, Conj. 1858. p. 76.

Arch, in Pritch. Inf. 1861, p. 723.

De Not, Desm. Ital. 1867, p. 20.

Rabenh. Flor. Europ. Alg. p. 148.

Delp. Spec. Desm. subalp. 1873, p. 77.

Wood, Freshw. Alg. N. Amer. 1873, p. 123.

Kirchn. Alg. Schles. 1878, p. 133.

Gay, Monogr. loc. Conj. 1884, p. 42 (in part).

Wolle, Desm. U. S. 1884, p. 28.

Cooke, Brit, Desm. 1887, p. 3.

De Toni, Syll. Alg. 1889, p. 788 (in part).

Wille in Engler, Nat, Pflanzenfam. 1890, p. 14.

Turn. Alg. E. India, 1893; p. 140 (in part).

Comere, Desm. de France, 1901, p. 198.

G. S. West, Brit, Freshw. Alg. 1904, p. 174.

Cells usually very small, flattened and deeply con-
stricted ; sinus open or narrow and linear ; semicells
elliptical, oblong or subrecfcangular, cells united to form
long filaments by means of special apical appendages,
often twisted and enveloped in a mucous investment ;
apex of each semicell provided with one or two pairs of
small rounded tubercles or short capitate processes,
which are closely applied to the corresponding processes
of the next cell. Chloroplasts axile, one in each semi-
cell, with a central pyrenoid.

SPHCEROZOSMA. 207

Zygbspore globose, rectangular or oblong, smooth, or
furnished with simple spines.

Sphcerozosma is distinguished from all other colonial Desmids
by its short apical processes. The only other genus in which
similar processes occur is Onychonema, but here they are very
much longer, so long as to overlap the cells in a very characteristic
fashion.

Dr. Liitkemuller in ' Zellmem. Desm.' 1902, p. 367, has expressed
the opinion that the short apical processes are not in themselves
the effective means by which the cells of the filaments are
united. He found that the real connecting link is a thin gela-
tinous cushion stretching between adjacent cells, in which the
processes of both are embedded. He further suggested that
possibly the real function of the apical processes is to counteract
to some extent the tendency of the filament to twist, a tendency
which, if allowed to become too strong, would eventually lead
to the breaking up of the filament.

The processes are sometimes very delicate, and only seen with
difficulty. They are usually observed most readily on the free
ends of the filament, or on isolated cells.

There are 5 British species of the genus, none of which is
abundant.

1. Sphaerozosma Auhertianum West.
(PL CLIX, fig. 13.)

Sphcerozosma Aubertianum West, Freshw. Alg. Maine, 1889, p. 206, t. 291,
f. 17 ; Alg. W. Ireland, 1892, p. 115, t. 19, f. 1 ; West & G. S. West,
Some N. Araer. Desm. 1896, p. 230, t. 12.

Cells small, about as long as broad, or a little broader,
deeply constricted, sinus acute, almost linear at first,
then opening more widely ; semicells narrowly elliptic
or almost elliptic-oblong, sides and apex gently rounded,
lateral margins with two distant minute granules,
arranged vertically ; semicells in side view subspherical,
with the connecting processes on each side of the apex ;
vertical view oblong-elliptic.

Zygospore globose or subglobose, with many long,
curved, and sharp spines, broad and hollow at the base.
Length of spines variable.

208 BRITISH DESMIDIACE^;.

Length of cells 16-5-19^ ; breadth 18-23 a ; breadth
of isthmus 5-8 \JL ; diam. zygosp. without spines 19-24 a ;
including spines, 37*5-42 p..

ENGLAND.- -Plank ton of Ennerdale Water, Cumber-
land !

WALES. — Capel Curig, Carnarvonshire !

IRELAND.- — Common in the plankton of Lough Aecory-
more, Achill Isle, Mayo ! Derryclare Lough, Gal way !

Geogr. Distribution.- -Finland. Australia. LTnited
States.

Var. Archeri (Gutw.) W. & G. S. West. (PI. CLIX,

figs. 14-17.)

Sphcerozosma vertebrate m Arch, in Q. J. M. S. 1865, v. 5, p. 170 ; ibid. I860,

v. 6, p. 274.
Sph. vertebratum forma Nordst. in Wittr. et Nordst. Alg. exs. no. 967^

fasc. 21, p. 34, 1889.
Sph. Archeri Gutw. Flor. Glon. Okolic Llowa, 1891, p. 29, t, 1, f. 4 ;

Roy & Biss. Scott. Desm. 1893, p. 10 ; Gutw. Flor. Glonow Okolic

Tarnapola, 1894, p 77.

? Sph.filiformis Turn. Alg. E. India, 1893, p. 142, t. 17, f. 20.
Sph. Aubertianum var. Archeri West & G. S. West, Some N. Amer. Desm.

1896, p. 230; Furth. Contrib. Plankton Scott. Lochs, 1905, p. 505,

t. 6, f. 7.

Differs from the type only in the fact that each semi-
cell is provided with two horizontal series of granules.

Zygosp ore exactly similar to that of the type.

Length 12-17 JJL ; breadth 19-27*5 \L ; thickness about
ll'Spi; breadth of isthmus 5 '5-7 pi; diam. zygosp.,
without spines, 19 ^ ; length of spines up to 17 [JL.

ENGLAND.- -Plankton of the English Lake District !

WALES.- -In the plankton !

SCOTLAND. --Near Alford and Braemar, Aberdeen
(Roy <& Biss.). Plankton of Lochs Shiel and Bairness,
Inverness !, and of Loch Eadaghoda, Lewis, Outer
Hebrides !

Geogr. Distribution. Sweden. Poland. India.
Australia.

Transitional forms between Sph. Aubertianum and its var.
Archeri are not at all uncommon, the two rows of granules being
very often incomplete. The variety is frequent in plankton.

Liitkemuller (' Desm. Bohm.' 1910) expresses the opinion that

SPH^ROZOSMA. 209

true warts do not occur in this species any more than in Sph.
vertebratum Ralfs, but that it is the hardened ends of gelatinous
strands exuding from 2 horizontal rows of pores which are often
visible even in the unstained cells. This is a good suggestion,
since the so-called granules are very delicate and often difficult
to see. From these considerations it would seem that Sph.
Aubertianum and its var. Archeri are quite possibly synonymous.

2. Sphaerozosma vertebratum (Breb.) Ralfs.
(PL CLIX, figs. 9, 10.)

DesmidiiiHi vertebratum Breb. Alg. Falaise, 1835, p. 269, t. 2.

Isthmia vertebrata Menegh. Synops. Desm. 1840, p. 205.

Desmidium compression Ralfs in Ann. Mag. Nat. Hist. vol. 9, 1842, p. 253.

Isthmo&ira vertebrata Kiitz. Phyc. Germ. 1845, p. 141 ; Spec. Alg. 1849,

p. 188.

Sphcerozosma unidentata Ralfs in Ann. Mag. Nat. Hist. vol. 16, 1846, p. 14.
Sph. verttbrntiini Ralfs, Brit. Desm. 1848, p. 65, t. 6, f. 1, t. 32, f. 2 : De

Bary, Conj. 1858, p. 45, t, 4, f. 32-34 ; Arch, in Pritch. Inf. 1861, p. 724,

t. 1, f. 15-17; Rabenh. Krypt.-fl. Sachs. 1863, p. 178; Jacobs. Desm.

Danem. 1875, p. 211 ; Kirchn. Alg. Schles. 1878, p. 133 ; Wolle, Desm.

U. S. 1884, p. 30. t, 4, f. 13 ; Cooke, Brit, Desm. 1887, p. 3, t. 2, f. 1 ;

Hansg. Prodr. Ahr. Bohm. 1888, p. 170 ; De Toni, Syll. Alg. 1889, p. 789 ;

West, Alg. Engl. Lake Distr. 1892, p. 6 ; Roy & Biss. Scott. Desm. 1893,

p. 10 ; Conn-re, Desm. de France, 1901, p. 199, t. 16, f. 12 ; West & G. S.

West, Alga-fl. Yorks. 1902, p. 110; Liitkem. Zellmem. Desm. 1902,

pp. 354, 366, t. 19, f . 8 ; G. S. West, Brit. Fre.slnv. Alg. 1904, p. 175,

f. 67 ('.

Cells small, about as long as broad, or sometimes a
little broader, constriction fairly deep, sinus narrow,
linear, obtuse at the apex ; semicells nearly oblong or
subreniform, slightly narrower at the apex ; lower
margin nearly straight, upper angles very rounded, apex
flattened ; lateral view of cell oblong, slightly con-
stricted in the middle, semicells short and oval ; apical
processes median ; cell-wall smooth. Chloroplasts axile,
with a central pyrenoid in each semicell.

Zygospore smooth and spherical (Ralfs).

Length 19(Ji; breadth 21-24 u ; thickness 12 \L ;
breadth of isthmus 9-1 0[/. ; diam. zygospore 21 \L.

ENGLAND. - Bassenthwaite Water, Cumberland !
Westmoreland! (Ralfs). Rawcliffe Common and Ingle-
borough, W. Yorks ! Strensall Common (W. B. Turner)
and Pilmoor. N. Yorks ! Riccall Common, E. Yorks !

VOL. V. 14

210 BRITISH DESMIDIACE.E.

Mitcham Common, Surrey ! Sussex arid Kent (Ralfs).
Dartmoor, Devon (Harris). Cornwall ! (Ralfs).

WALES. — Capel Curig ! (Cooke & Wills) and Glyder
Fawr (Roy), Carnarvonshire. Dolgelly, Merioneth (Ralfs).
In the plankton !

SCOTLAND. --Aberdeen, Kincardine, Forfar, Perth (Roy
& Biss.). Shetlands ! Not uncommon in the plankton !
Plankton of Loch Gorma, Inverness ; and of Loch
Diracleet, Harris, Outer Hebrides !

IRELAND.- -In the plankton, Mayo ! Derryclare Lough,
Ballynahinch, and in the plankton, Galway ! Lough
Guitane and in the plankton, Kerry !

Geogr. Distribution. --Fiance. Belgium. Germany.
Switzerland. Galicia in Austria. Hungary. Italy.
Turkey. Norway. Sweden. Denmark. Bornholm.
Finland. N. and S. Russia. Faeroes. India. United
States. Patagonia.

Forma minor West. (PL CLIX, fig. 12.)

Sph. vertebratum f. minor West, Add. Alg. W. Yorks. II, 1891, p. 244 ;
Alg. Engl. Lake Distr. 1892, p. 6, t. 9, f. 3.

Differs from the type in its smaller size, its relatively
broader isthmus, and somewhat more depressed cells.

Length 8-10 u. ; breadth 12-14 \L ; breadth of isthmus
7-5-8(1.

ENGLAND.- -Harrop Tarn, Cumberland ! Brother's
Water, Rydal Fell, and Stickle Tarn, Westmoreland !
Malham Tarn, W. Yorks !

Var. punctulatum W. & G. S. West. (PL CLX, fig. 12.)

Sph. punctulatum West, Alg. Maine, 1891, p. 1, t. 315, f. 1, 2.
Sph. vertebratum var. punctulatum West & G. S. West, Freshw. Alg. Orkneys
& Shetlands, 1905, p. 28 ; Phytoplankton Engl. Lake Distr. 1909, p. 290.

Cells more angular than in the type, and distinctly
punctate.

Length 14-16 [JL; breadth 17'o-20p; thickness 10 pi;
breadth of isthmus 8-9 '5 .

SPH.EROZOSMA. 211

ENGLAND.- -Plankton of Ennerdale Water, Cumber-
land !, and of Brother's Water, Westmoreland !
SCOTLAND. --Near Scalloway, Shetlands !

The differences between this variety and Sph. Aubertianum
var. Archeri are often very slight, so that it is difficult to distin-
guish between them. The latter Desmid seems, however, to
be relatively longer, whilst the punct illations in SpJi. vertebratum
var. punctidatum are more evenly distributed.

Var. latins W. & G. S. West, (PL CLIX, fig. 11.)

Sjth. vertebratum var. latins West & G. S. West, Alg. S. Engl. 1897, p. 497,
t. 6, f. 7.

Cells much wider than in the type, up to If times
broader than long ; sinus narrower and deeper ; apex
of semicell more convex.

Length 15-16 [i ; breadth 25-27 [JL ; breadth of isth-
mus 5 '5-7 "5 JJL.

ENGLAND. — Esher West End Common, Surrey !

3. Sphserozosma excavatum Ralfs.
(PL CLX, figs. 1-3.)

Splicerozosma excavatum Ralfs in Ann. Mag. Xat. Hist. vol. 16, 1845, p. 15,
t. 3, f. 8 ; Brit. Desm. 1848, p. 67, t. 6, f . 2 ; De Bary, Conj. 1858, p. 45 ;
Arch, in Pritch. Inf. 1861, p. 724; Rabenh. Krypt.-fl. Sachs. 1863,
p. 178 ; Reinsch, Alg. Frank. 1867, p. 199 ; De Not. Desm. Ital. 1867,
p. 29, t, 1, f. 5 ; Rabenh. Flor. Europ. Alg. 1868, p. 149 ; Xordst. Desm.
Brasil, 1869, p. 205; Jacobs. Desm. Danem. 1875, p. 211; Kirchn.
Alg. Schles. 1878, p. 133 ; Wolle, Desm. U. S. 1884, p. 29, t. 4, f. 8-12 ;
Cooke, Brit. Desm. 1887, p. 4, t, 2, f. 2 ; Hansg. Prodr. Alg. Bohm. 1888,
p. 170 ; De Toni, Syll. Alg. 1889, p. 790 ; West, Alg. X. Wales, 1890, p. 6 ;
Alg. Engl. Lake Distr. 1892, p. 6 ; Alg. W. Ireland, 1892, p. 115 ; Gutwin.
Flor. Glonow Galic. 1892, p. 15 ; Roy & Biss. Scott. Desm. 1893, p. 10 ;
West & G. S. West, Some X. Amer. Desm. 1896, p. 231, t. 12, f. 9 ;
Comere, Desm. de France, 1901, p. 198, t. 16, f. 14 ; West & G. S. WTest,
Alga-fl. Yorks. 1902, p. 110; Alg. X. Ireland, 1902, p. 59; G. S. West,
Brit. Freshw. Alg. 1904, p. 175, f. 67, D-F ; West & G. S. West, Freshw.
Alg. Orkneys & Shetlands, 1905, p. 28; Cushman in Rhodora, 1905,
p. 264 ; in Bull. Torr. Bot, Club, 1905, p. 552 ; ibid. 1907, p. 615.

Isihmosira excavata Kiitz. Spec. Alg. 1849, p. 189.

Cells very small, usually only slightly longer than
broad, but sometimes as much as twice as long as broad,
constriction moderately deep, sinus widely excavated,

212 BKITISH DESMIDIACE.E.

obtuse ; semicells broadly oval, isthmus slightly
elongated ; lateral view of cell oblong-elliptic, sides
slightly concave ; vertical view oblong with rounded
ends and 4 minute attaching processes on the long
margins. Cell-wall usually smooth, sometimes with
horizontal rows of minute granules. Chloroplasts axile,
one in each semicell with a central pyrenoid.

Zygospore rather large in proportion to the size of
the cells, oval or spherical, wall quite smooth. Ralfs
(' Brit. Desm.' 1848) records the occurrence of lateral
conjugation in this species.

Length 7 "5-12^ ; breadth 7-14 fi ; breadth of isth-
mus 3* 5-6 "5 [i ; thickness 5-7 u ; length of zygospore
10-2-16 [i ; breadth 9-11 ^.

ENGLAND. - - Cumberland ! Westmoreland ! (Rolfs).
Lancashire (Rolfs}. W., N., and E. Yorks ! Leicester
(Roy}. Burnham Beeches, Bucks ! Warwicks (Wills).
Gloucester (Rolfs}. Surrey ; zygospores from Putten-
ham arid Thursley Commons ! Sussex ; Kent (Rolfs}.
Hants ! (Roy} ; zygospores from New Forest ! Devon \
(H orris}. Cornwall ! (Rolfs}.

WALES. — Snowdon !, Llyn Padarn !, Llyn Idwal !,
Capel Curig ! (Cooke & Witts) and Glyder Each (at
2200 feet) !, Carnarvonshire. Radnor !

SCOTLAND. — General and frequently conjugated ! (Roy
& Biss.}. Shetlands !

IRELAND.- -General ! Wicklow ! Plankton of Galwav !

t>

Geogr. Distribution- -Erance. Germany. Switzerland.
Galicia in Austria. Hungary. Servia. Italy. Portugal.
Norway. Sweden. Denmark. Finland. S. Russia. Nova
Zembla. Spitzbergen. Greenland. India. Australia.
Abyssinia. Central Africa. United States. N.W.Canada.
Brazil.

Var. subquadratum var. nov. (PI. CLX, figs. 4, 5.)

Spli. excavatum var. subquadratum West & G. S. West in manuscript.

Cells relatively broader than in the type, deeply con-
stricted, sinus narrow and obtuse at its apex ; semicells

SPH.EROZOSMA. 213

oblong, upper angles more broadly rounded than the
lower ones ; vertical view narrowly elliptic.

Length 7'8-8'8pi ; breadth 9-10 ^ ; breadth of isth-
mus 2*5-3 VL ; thickness 3 '7 pi.

ENGLAND. — Stickle Tarn and Brother's Water, West-
moreland !

This tiny variety has a very different appearance from the
typical form, and bears a strong resemblance to Sph. vertebmtum
Ralfs forma minor West, from which it differs in its extremely
deep constriction.

4. Sphaerozosma granulatum Roy & Biss.

(PL CLX, figs. 6, 7.)

Splicerozosma excavafum forma Javanica Xordst. Alg. et (liar. I, 1880, p. 3.
''. XpJi. spinulosum Delp. in Wolle, Desm. U. S. 1884, p. 31, t. 4, f. 14.
Xph. granulatum Roy & Biss. Jap. Desm. 1886, p. 242, f. 17; Nordst.

Freshw. Alg. N. Zeal. 1888, p. 28 ; De Toni, Syll. Alg. 1889, p. 791 ;

Rov. Freshw. Alg. Enbridge Lake and Vicin. 1890, p. 335 ; Anderss.

Sverig. Chlorophy. 1890, p. 9 ; West, Alg. Maine, 1891, p. 353 ; Alg.

Engl. Lake Distr. 1892, p. 6 ; Alg. W. Ireland, 1892, p. 115 ; Liitkem.

Desm. Attersees, 1893, p. 539 ; Roy & Biss. Scott. Desm. 1893, p. 10 ;

West & G. S. West, Alga-fl. Yorks. 1902, p. 110; A1-. X. Ireland, 1902,

p. 59 ; Alg. Ceylon, 1902, p. 193 ; Alg. Orkneys & Shct lands, 1905, p. 28.

Cells small, about as long as broad, constriction deep
and open ; semicells elliptical, lateral margins rounded,
apex straight ; apical processes widely separated ;
semicells with a group of minute granules at each lateral

O .( O

margin, about 3 of which are visible ; semicells from
the side rounded, with about 6 small granules surround-
ing a central one. Chloroplasts axile. one in each
semicell, with a central pyrenoid.

Zygospore cubical, smooth, with one or two short,
stout, and blunt spines on each angle (Roy}.

Length 8-9 \i ; breadth 8-1 0(i ; breadth of isthmus
4-5 ;JL ; length and breadth of zygosp. 14 '5 \L ; length of
spines 3 '5 \i.

ENGLAND.- -Wastdale, and in the plankton of Enner-
dale Water, Cumberland ! Bowness, and in the plankton
of Hawes Water and Codale and Easedale Tarns, West-
moreland ! Hampsfell, Lancashire ! Pilmoor, N. Yorks !

214 BRITISH DESMIDIACE^E.

Biccall Common. E. Yorks ! Epping Forest, Essex f
Warwicks ! Worcs ! Near Chapel Wood, and Puttenham
Common, Surrey ! Enbridge Lake, Hants., with zygo-
spores (Roy}.

WALES.- -Llyn Idwal, Llyn Ogwen, Llyn Geirionedd,
and Llyn Bodgynwydd, Carnarvonshire !

SCOTLAND. Sutherland !, Inverness !, Aberdeen,
Kincardine, Forfar, Perth ! and Argyle (Roy & Biss,).
Not uncommon in the plankton ! Frequent in Lewis,
Outer Hebrides ! Shetlands and also in the plankton !

IRELAND. Donegal ! Mayo ! Galway ! Kerry t
Armagh !

Geogr. Distribution.- -Germany. Galicia and Austria.
Sweden. Bornholm. N. Eussia. Manchuria. Central
China. Japan. Ceylon. Java. Australia. New Zealand.
Nova Scotia. United States. Porto Rico. Colombia.
Brazil. Paraguay. Patagonia.

Var. trigranulatum W. & G. S. West. (PL CLX, fig. 8.)

Sph. granulatum var. trigranulatum AVest & G. S. West, Alg. N. Ireland,
1902, p. 59, t, 2, f. 18.

Cells slightly longer than in the type ; semicells with
3 granules only on each side, arranged in a vertical series
on the lateral margin.

Length 10'2-11'3 ;JL ; breadth 10'6 [/. ; thickness 5'8 [i ;
breadth of isthmus 5 [JL .

IRELAND. — Gortahork, Donegal !

5. Sphaerozosma Wallichii Jacobs.
(PI. CLX, fig. 9.)

Sphcerozosma excavatum /3 Wallich, Desm. Low. Bengal, 1860, p. 192, t. 7,

f. 15.
Sph. Wallichii Jacobs. Desm. Danem. 1875, p. 211 ; ? Wolle, Desm. U. S.

1884, p. 30, t. 4, f. 15 ; De Toni, Syll. Alg. 1889, p. 794 ; Turn. Alg. E.

India, 1893, p. 141, t. 18, f. 1, 12, 13 ; Johns. New Rare Desm. 1894,

p. 286 ; West & G. S. West, Desm. U. S. 1898, p. 320 ; Borge, Alg. erst.

Regnell. Exped. II, Desm. 1903, p. 121.

Sph. excavatum [3 Wallichii Nordst. in Pointsf. Skandin. Vaxt. 4, 1880, p. 24.
. Eegnesi Schmidt, Grundl. Algenfl. Liineburg. Heide, 1903, p. 21-23,

t. 1, f. 12.

OXYCHONEMA. 215

Cells small, slightly broader than long, constriction
fairly deep, sinus oval in shape, semicells narrowly
oblong, angular, -sides truncate with a granule at each
angle, apex slightly convex ; semicells with 2 granules
placed symmetrically on each broad face ; cells in
lateral view very slightly constricted, semicells rounded,
with 2 granules in a vertical series.

Zygospore unknown.

Length 15-16^; breadth 16- 17 a.; thickness 8 (x ;
breadth of isthmus 6-7 y. .

SCOTLAND.- -Inverness, Aberdeen and Kincardine (Roy
& Biss.).

Geoyr. Distribution. — Sweden. Denmark. Bengal.
Australia (form). United States. Brazil (form).

Var. anglicum W. & G. S. West. (PI. CLX, figs.

10, 11.)

Sph. ]\'iillic/tii var. <(iit//i<:ii»i West & G. S. West, Alg. S. England, 1897,
p. 497, t. 15, f. li.

Apex of semicell slightly convex, sinus smaller than
in the type, with 2 or 3 granules on the lateral margins
of the semicells, and others scattered sparsely and
irregularly across the surface.

Length 10-ir5ku.; breadth lO'5-ll u. ; breadth of
isthmus 6 JJL ; thickness o '5 u..

ENGLAND. --Xew Forest, Hants ! (Abundant July,
1897.)

Genus 22. ONYCHONEMA Wallich, 1860.

Wallich, Desm. Low. Bengal, 1860, p. 194.

Cooke, Brit, Desm. 1887, p. 6.

De Toni, Syll. Alg. 1889, p. 795.

Wille in Engl. Naturl. Pflanz. Fam. 1890, p. 14.

Turn. Freshw. Alg. E. India, 1893.

G. S. West, Brit, Freshw. Alg. 1904, p. 175.

Cells small, forming simple filamentous colonies, com-
pressed, deeply constricted, sinus narrow ; semicells
elliptic or reniform, sometimes with strong lateral

216 BRITISH DESMIDIACE^.

spines ; each semicell with 2 capitate processes of con-
siderable length projecting from its apex ; processes
disposed asymmetrically, and overlapping the adjacent
cell. Chloroplasts axile, one in each semicell, with a
central pyrenoid. Filaments long and twisted, and often
embedded in a mucous investment.

Zygospores only known in one species, globose, with
many simple spines.

The genus Onychonema is closely allied to Sphcerozosma, from
which genus it differs in the size and arrangement of its apical
processes. In Onychonema the two processes of each semicell
do not apply themselves to the processes of the neighbouring
semicell, but overlap it in a characteristic way, so that in the
front view, all the processes on the left of the filament are
disposed in one direction, and all those on the right in the
opposite direction.

As in Sphcerozosma, Lutkemiiller (in 'Zellmembr. Desm.' 1902,
p. 367) has expressed his doubts that these apical processes are
really for the purpose of attaching the cells together, and has
demonstrated the presence of two cushions of jelly, closely in
contact, filling up the space between the cells (in Onychonema
filiforme), which he considered to be the real agents in effecting
the attachment. As in Sphcerozosma also, he suggests that their
real function is to counteract the tendency of the filaments to
twist, a tendency present in an almost dangerous degree.

Both species of Onychonema are very rare.

1. Onychonema filiforme (Ehr.) E. & B.
(PL CLX, figs. 13, 14.)

Tessararthrafilifornns Ehr. Inf. 1838, t. 10, f. 21.

? Odontellafiliformis Ehr. Inf. 1838, p 154.

IsthmiafiliformisMeuegh. Synops. Desm. p. 205.

Isthmosira filiformis Kiitz. Phyc. Germ. 1845, p. 141 ; Spec. Alg. 1849,

p. 188.
Sphcerozosma filiformis ? Ealfs, Brit. Desm. 1848, p. 209 ; Arch, in Pritch.

Inf. 1861, p. 724 ; Rabenh. Flor. Eur. Alg. 1868, p. 149 ; Arch, in Quart.

Jourii. Micr. Sci. v. 9, 1869, p. 198 ; Lund. Desm. Suec. 1871, p. 91 ;

Kirchn. Alg. Schles. 1878, p. 133 ; Wolle, Desm. U. S. 1884, p. 29, t. 4,

f. 5, 6 ; Cooke, Brit. Desm. 1887, p. 5, t. 2, f. 6 ; Hansg. Prodr. Alg.

Bohm. 1888, p. 170 ; Comere, Desm. de France, 1901, p. 199, t. 16, f. 6.
Onychonema Nordstedtianum Turn. New Rare Desm. 1885, p. 934, t. 15,

f. 3 ; Cooke, Brit. Desm. 1887, p. 6, t. 2, f. 7 ; Nordst. Desm. Bornh.

1888, p. 208 ; De Toni. Syll. Alg. 1889, p. 796 ; West, Alg. N. Wales,

1890, p. 7 ; Turn. Alg. E. Ind. 1893, p. 139, t. 17, f. 17 ; Roy & Biss.

ONYCHONEMA. 217

Scott. Desm. 1893, p. 11 ; West &• G. S. West, Alga-fl. Yorks. 1902,
p. 110; Alg. N. Ireland, 1902, p. 59; G. S. West, Brit. Freshw. Alg.
1904, p. 175, f. 67, G, H.

Onychonema fill for me Roy & Biss. Jap. Desm. 1886, p. 242 ; Nordst.
Freshw. Alg. New Zeal. 1888, p. 29, t, 2, f. 10 ; De Toni. Syll. Alg. 1889,
p. 786 ; Anders. Sverig. Chloroph. 1890, p. 9 ; West, Notes Dan. Alg.

1891, p. 1 ; West, Alg. W. Ireland, 1892, p. 116 ; Alg. Eng. Lake Distr.

1892, p. 6 ; Roy & Biss. Scott. Desm. 1893, p. 11 : West & G. S. West,
Alg. S. England, 1897, p. 497 ; G. S. West, Brit. Freshw. Alg. 1904, p. 175 ;
Kaiser, Alg. Traunstein u. Chiem. 1914, p. 153.

Xjthcerozosma vertebratum Hauptti. Zellm. u. Hullgallerte Desm. 1888. p. 21
(sep.), t. 2, f. 16-23, 27.

Cells small, about as long as broad, deeply constricted,
sinus narrow, almost linear ; semicells elliptical or sub-
reniform, ventral nwrgin almost straight, dorsal margin
broadly rounded ; semicells with two long processes,
nearly as long as the semicell itself ; disposed asymmetric-
ally, and overlapping the adjacent cell of the filament
(only one of the processes of any semicell is seen in the
front view, the second one being on the opposite side of
the filament). Cells united to form long twisting fila-
ments, the cells often separated from each other by a
greater or smaller space.

Zygospore unknown.

Length, not including processes, 9-12*5 JJL ; breadth
1 0-12*5 fx ; thickness 5-6*4 \L ; breadth of isthmus 3*5-4 u.

ENGLAND.- -Bowness, Westmoreland ! Pilmoor and
Strensall Common (W. B. Turn.}, N. Yorks! Skipwith
and Riccall Commons, E. Yorks ! Dartmoor, Devon
(Harris). Gunwen Moor, Cornwall !

WALES. — Capel Curig, Carnarvonshire !

SCOTLAND.- -Xear Strathpeffer, Eoss ; Lochs Ruthven,
Aschie, Coire, near Brin, Inverness ; Aberdeen and
Kincardine (Roy & Biss.). Ehiconich, Sutherland !

IRELAND. --Near Glenties and Lough Anna, Donegal !
Eoundstone, Mayo ! Lakes near Eecess, Clifden and
Derryclare Lough, Galway ! Tipperary (Arch.). Ulster,
Minister and Connaught (Adams).

Geogr. Distribution.- -France. Germany. Galicia in
Austria. Sweden. Denmark. Bornholm. Poland.
Japan. Celebes. India. New Zealand. Australia.
Tasmania. United States. Colombia.

218 BRITISH DESMIDIACE^.

After very careful consideration the writer has failed to find
any essential differences between 0. filiforme (Ehr.) R. & B. and
0. Nordstedtianum Turn. Only one difference seems to have been
recognised by earlier writers, namely, that 0. filiforme has
larger or smaller spaces between the adjacent cells of the fila-
ment, whilst in 0. Nordstedtianum adjacent cells are contiguous
with one another. As Liitkemuller ('Zellm. Desm.' 1902, p. 367)
has shown, however, the cells are actually separated by gela-
tinous cushions, and it is presumably the size of these which
determines the spacing of the cells. It is improbable that specific
distinctions can be based on such a character, and it has therefore
been deemed better to unite the two under the older name of
0. filiforme (Ehr.) R. & B.

2. Onychonema laeve Norclst.
(PI. CLX, figs. 15, 16.)

Onychonema Iceve Nordst. Desm. Brasil, 1870, p. 206, t. 3, f. 34 ; Reinsch,
Contrib. Fung, et Alg. 1875, p. 93, t, 15, f . 4 ; De Tom, Syll. Alg. 1889,
p. 796 ; Turn. Freshw. Alg. E. India, 1893, p. 139, t. 17, f. 15A ; Roy &
Biss. Scott. Desm. 1893, p. 11 ; Racib. Desm. Tapakoomas, 1895, p. 32 ;
West & G. 8. West, Alg. Ceylon, 1902, p. 193 ; Alg. Burma, 1907, p. 224,
t, 12, f. 8-10.

Xanthidiastnan paradoxum Delp. Spec. Desm. Subalp. 1877, p. 80, t. 3,
f. 27-33.

Cells larg'er than in 0. filiforme, slightly broader than
long, deeply constricted, sinus narrow for part of its
length, dilated at the apex, and opening widely ; semi-
cells oblong or subreniform, attenuated towards the
lateral angles and ending in a long stout converging
spine ; apical processes rather shorter than the spines ;
vertical view elliptic, drawn out into a spine at the two
poles. Filaments usually embedded in a mucous in-
vestment.

Zygospores spherical, with many short, stout, simple
spines.

Length 16-1 7 pt. ; breadth, without spines, 20 "5-25^ ;
including spines, 25-46 \i : breadth of isthmus 6 \L ;
diam. zygosp., without spines, 17-20 pi; with spines,
24-26 pJ

SCOTLAND.- -Found once by the side of the old road
from Aboyne to Kincardine O'Neil, about a mile from
Aboyne, Aberdeen (Roy & Biss.).

SPONDYLOSIUM. 219

Geoyr. Distribution. — Japan (var.). India. Ceylon.
Burma. Java. Australia. East and Central Africa (var.).
United States. W. Indies (var.). Guiana. Brazil.
Paraguay ( va r . ) .

This species is very rare in Britain, and indeed in the whole
of Europe. There is only the one record of it for the British
Isles.

The spore figured on PL CLX, fig. 16 is peculiar in having
been produced apparently from a single cell. The authors of
this Monograph were undecided whether it should be considered a
true zygospore or an aplanospore. In its external form it is
essentially similar to the zygospore of the variety micracanthum
of this species (see PL CLX, fig. 17). This variety is rather
more frequent than the type form, though it does not occur in
North Temperate regions. The normal zygospore of the typical
form has not vet been observed.

Genus 23. SPONDYLOSIUM Breb. 1844.

Breb. in Diet. univ. hist. nat. 4, 1844, p. 711 (Spondylotium).

Kiitz. Spec. Alg. 1849, p. 189.

De Bary, Conj. 1858, p. TO.

Arch, in Pritch. Inf. 1861, p. 724.

Kirchn. Alg. Schles. 1878, p. 133.

De Toni, Syll. Alg. 1889, p. 792.

Wille in Eiigler, Naturl. Pflanzenfam. 1890, p. 14.

Turn. Freshw. Ate. E. India, 1893, p. 47.

G. S. West, Brit. Freshw. Alg. 1904, p. 175.

Leuronema \Yallich, Desm. Low. Bengal, 1860, p. 193.

Cells usually small, or of medium size, flattened and
often deeply constricted with a narrow or open sinus ;
semicells variable in shape, often with broadly truncate
or concave apices ; in vertical view elliptical, triangular
or trilobed ; chloroplasts axile. Cells united to form
long filamentous colonies by the simple close apposition
of their apices, sometimes twisted and often enveloped
in mucilage. In one species the filaments are often

O j-

observed attached to other aquatic plants by means of
a short basal gelatinous cushion.

o

Zygospores usually globose and smooth, or with
simple spines. Lateral conjugation through the apices

220 BRITISH DESMIDIACE^:.

of the cells of the filament has been observed in one
instance.

The genus Spondylosium is very closely allied to Spkcerozosma,
the sole distinguishing feature being the absence of the short
apical processes between the cells which are characteristic of the
latter genus.

All the British species are comparatively rare, and do not
commonly occur in abundance. They may be arranged as
follows : —

: Semicells elliptical or subelliptical.

*}• Apex of semicell straight or slightly convex, never
concave.

1. Sp. pyymmun.

2. Sp. ellipticum.

3. Sp. planuin.

4:. Sp. papillosum.

5. Sp. Lundettii.
ft Apex of semicell distinctly concave.

6. Sp. secedens.

Cells more or less rectangular ; sinus a very shallow excava-
tion.

7. Sp. tetragonum.
Semicells truncate-pyramidate.

8. Sp. pulchellum.

1. Spondylosium pygmaeum (Cooke) West.
(PL CLX, figs. 18, 19.)

Sphcerozosma pygniceum Cooke, Brit. Desm. 1887, p. 5, t. 2. f. 5. [This is
not Sph. pygmceum Rabenh.] West, Alg. N. Wales, 1890, p. 6.

Spondylosium pygmceum West, Freshw. Alg. W. Ireland, 1892, p. 11(3
(Sphcerozosma by printer's error) : West & G. S. West. Rec. publ. Desm.
1895, p. 65 ; Alga-fl. Yorks. 1902, p. 95.

Cells minute, about as long as broad, sometimes
slightly broader than long, deeply constricted, sinus
acute, almost linear for part of its length ; semicells
elliptical, united by a relatively small surface of their
apices to form long filamentous colonies, frequently
enclosed in a gelatinous investment ; cell- wall smooth ;
vertical view subelliptic.

Zygospore unknown.

SPONDYLOSIUM. 221

Length 5-8 u. ; breadth 5-8 p ; breadth of isthmus
2-5-3-2 pi.

ENGLAND. — Mickle Fell, N. Yorks ! Riccall Common,
E. Yorks ! Dartmoor, Devon (Harris}.

WALES. — Capel Curig, and Dolbadarn Castle, Car-
narvonshire ! Barmouth, Merioneth (CooJce).

IRELAND . — Connaught (Adams) .

Geogr. Distribution. — Germany. Switzerland. Ron-
mania. Norway. S. Africa (var.). Azores.

Some confusion has arisen with regard to this species, owing
to the fact that Cooke was under the impression that his Sphc&ro-
zosma pygmceum was equivalent to the species described under
that name in Eabenh. 'Flor. Europ. Alg.' 1868, p. 150. This is
not so, however, for Sphcerozosma pygmceum Kabenh. is the
same as Cos) Barium pygmceum Arch., which is a true Cosmarium,
and has nothing at all to do with the filamentous Desmids [vide
Vol. Ill, p. 73].

Var. monile (Turn.) nob. (PL CLX, figs. 20, 21.)

Spondylosium monile Turn. Desm. Notes, 1893, p. 346, f. 19. [Side view
inaccurate.]
' pygtnceuiii var. monile W. £• G. S. West in manuscript.

Cells relatively longer than in the type, semicells
more broadly oval, semiglobular ; cells in side view
gently constricted in the middle.

Length about 7 JJL ; breadth about 4 y. ; thickness
about 3 {jt.

WALES.- -Trelleck Common, Monmouth (Turn.).

IRELAND.- -Westport, Mayo !

Var. compressum West. (PL CLX, fig. 22.)

Sp. pygmceum var, compressum West, Alg. Engl. Lake Distr. 1892, p. 6, f. 4.

Cells in outline subquadrangular, sinus linear, semi-
cells compressed, oblong, with their apices flattened.

Length 5 '5-6^; breadth 7 ^ ; breadth of isthmus
2-5 [i.

ENGLAND. — Brother's Water, Westmoreland !

222 BRITISH DESMIDIACE^E.

2. Spondylosium ellipticum W. & G. S. West.

(PL CLXI, fig. 15.)

Spondylosium elliplicum West & G. S. West, Alg. N. Ireland, 1902. p. 43,
t. 2, f. 21.

Cells of medium size, about as long as broad, deeply
constricted, sinus open and acute ; semicells exactly
elliptical, apices convex, not flattened ; semicells in
side view subspherical ; from the end, elliptical ;
chloroplasts one in each semicell with a central pyrenoid.
Cells forming twisted colonies, with no mucous sheath.

Zygospore unknown.

Length 19 '6-24 ^ ; breadth 20-22 pi ; thickness 11*5-
12 pi ; breadth of isthmus 6 '7-7 \L.

IRELAND.- -Lough Fea, Londonderry !

This species approaches S. ovale, Turn, (in 'Alg. E.Ind.' 1893,
p. 44, t. 18, f. 3, 9), but it is distinguished by its smaller size,
its relatively longer cells, its much deeper constriction, and by
the perfectly elliptical semicells. It is also more deeply con-
stricted in the side view than S. ovale, and only one pyrenoid is
present in a semicell.

It also resembles to a certain extent S. planum (Wo lie) W.
.& G. S. West, but the more depressed semicells of the latter
species distinguish it.

3. Spondylosium planum (Wolle) W. & G. S. West.

(PL CLX, figs. 23-25.)

Sphcerozosma pulchrum var. planum Wolle, Desm. U. S. 1884, p. 29, t. 4,

f. 3, 4 ; De Toni, Syll. Alg. 1889, p. 794.

Spondylosium ovale Turn. Alg. E. India, 1893, p. 44. t. 18, f. 3, 9.
Sp. pulchrum var. planum W. & G. S. West, Obs. Conj. 1898, p. 54 ; Scott.

Freshw. Plankt. 1, 1903, p. 551.
Sp. planum W. & G. S. West, Periodic. Phytopl. Brit. Lakes, 1912, p. 430,

t. 19, f. 5-8,

Cells of medium size, about 1^ times broader than
long, subquadrangular, angles rounded, deeply con-
stricted, sinus obtuse, open ; semicells transversely
oblong, angles broadly rounded, apices flat ; in vertical
view oblong with rounded ends ; from the side sub-

SPONDYLOSIUM. 223

circular ; cell-wall smooth ; cells united into filaments,
not twisted, and destitute of a gelatinous sheath.

Zygospores have been recorded, but without descrip-
tion.*

Length 11 '5-19 *5 [/. ; breadth 12-25 ku. ; thickness
6-1 1 (JL ; breadth of isthmus 5-1 1 "5 p .

ENGLAND.- -Plankton of Crummock Water, Derwent
Water, Bassenthwaite Water, and Thirlmere, Cumber-
land ! Plankton of Ked Tarn, Ullswater, Hawes Water,
Grasmere and Windermere, Westmoreland !

WALES.- -Llyn Ogwen, Carnarvonshire !

SCOTLAND.- -Plankton of Lochs nan Cuinne and Shin,
Sutherland!, of Lochs Luichart and Rosque, Ross!,
of Lochs Tay, Katrine, and Achray, Perth !, and Loch
Cuthaig, Lewis, Outer Hebrides !

IRELAND.- -Plankton of Mayo !, Galway ! and Kerry !

Geogr. Distribution.- -Xorway. United States and
Alaska. Canada.

This species, considered for a long time to be a variety of Sp.
pulchrum (Bail.) Arch., was finally given specific rank in view of
its constant and distinctive characters. There is no possibility
of confusing it with any other species of Spondylosium, and it
has little, if any, relationship with Sp. pidchrum, differing in its
much smaller size, in its plane untwisted filaments, and in the
flattened closely applied apices of the semicells. The semicells
are of a different form from those of Sp. pulchrum, and the cells
are proportionately longer. It is a common species in the plank-
ton of many British lakes.

4. Spondylosium papillosum W. & G. S. West.

(PL CLXI, figs. 6, 7.)

Sphcerozosma depressum West, Alg. N. Wales, 1890, p. 7 ; Schmidle, Alg.

Bern. Alp. 1894, p. 87 ; Beitr. Alp. Alg. 1895, p. 9.
Spondylosium depressum Kirchn. Micr. Pflanz. Siissw. 1891, p. 21, t. 2,

f. 61.
Sp. papillosum W. & G. S. West, Alg. Mad. 1895, p. 43, t. 9, f. 19 ; Notes

Alg. I, 1898, p. 5 ; Alga-fl. Yorks. 1902, p. 95 ; Alg. N. Ireland, 1902,

p. 43 ; Notes Alg. Ill, 1903, p. 10 ; G. S. West, Brit. Freshw. Alg. 1904,

p. 176, f. 67 B (papillatum in error).
Sphcerozosma papillosum Schmidle, Alg. aus. Nyassa See, 1903, p. 75.

* Lateral conjugation is reported by W. & G. S. West in specimens from
Maine (* Obs. Conj.' 1898, p. 54), but no description is given.

224 BRITISH DESMIDIACE^.

Cells very small, as long as or slightly longer than
broad, constriction moderately deep, sinus obtuse and
open ; semicells elliptical, with truncate apices ; lateral
margins provided with 3 very minute granules ; semi-
cells in side view subcircular. Cells united to form
twisted filaments, destitute of a gelatinous sheath.

Zygospore unknown.

Length 8-9 '5 pi ; breadth 8 '5-9 '5 pi ; thickness 5 \JL :
breadth of isthmus 4-5 '5 (JL.

ENGLAND; — Skipwith Common, E. Yorks ! Har-
borne, and in the plankton of Bracebridge Pool, Button
Park, Warwickshire !

WALES. — Capel Curig, Dolbadarn Castle, near Llan-
beris, and Llyn-y-cwm-ffynon, Carnarvonshire !

SCOTLAND.- -Rhiconich, Sutherland !

IRELAND. --Near Glenties, Donegal !

Geogr. Distribution. — Germany. Australia. Madagas-
car. Central and E. Africa. United States.

This species, which is nearest to Sp. tetragomrm W. & G. S.
West, is one of the least rare of the British species of Spon-
dylosium, although, being, at the same time, not at all common.

Some confusion has arisen owing to the fact that it was not
made clear in the older compilations of Rabenhorst and De Toni,
whether the protuberances of Sp. depressum Breb. are apical
or lateral in position. In true Sp. depressum Breb. they are, of
course, apical. This species has never been found in Britain.
The looseness of these descriptions led to a form identical with
Sp. papillosum West being figured by Kirchner (' Micr. Pflanz.
Siissw.' 1891, p. 21, t. 2, f. 61) as Sp. depressum. Thus Sp. papil-
losum W. & G. S. West embraces Sp. depressum Kirchn., but not
Breb.

5. Spondylosium Lundellii Borge.

Spondylosium pulchrum forma Lund. Desm. Suec. 1871, p. 93, t. 5, f. 17 ;

Delp. Spec. Desm. subalp. 1877, p. 77, t. 3, f. 11.
Sp. Lundellii Borge, Sao Paulo Alg. 1919 p. 71, t, 6, f. G.

Cells of medium size, about 1| times broader than long,
constriction not deep, sinus acute, opening widely ; semi-

SPONDYLOSIUM. 225

cells oblong, with rounded ends, apex convex, but
flattened on the top ; in lateral view with rounded sides ;
vertical view subrectangular. sides nearly straight or
very slightly convex, ends rounded and produced, and
asymmetrical, there being a slight concavity on the
right side of the one produced end. and on the left side
of the other. Cells united into long twisting filaments.

Zygospore unknown.

Length lS'o-20^: breadth 28-33 u ; thickness 16-
19 (JL ; breadth of isthmus 20-24-5 u.

Geogr. Distribution. — Sweden. Italy.

Var. triquetrum (Lund.) nob. (PL CLXVII, fig. 10.)

Sp. pulclirum var. triquetrum Lund. Desm. Suec. 1871, p. 93 ; West, Alg.
W. Ireland, 1892, p. 116, t. 19, f. 3.

Cells in vertical view triangular, angles obliquely
rounded-truncate ; chloroplast axile with a central
pyrenoid.

Length 20-24 u ; breadth 28-36 ;JL ; breadth of isth-
mus 22-27(i.

IRELAND.- -Lakes. Clifden to Roundstone, Galway !

Geogr. Distribution. — Sweden.

6. Spondylosium secedens (De Bary) Arch.
(PL CLXL figs. 8-11.)

Sphcerozosma secedens De Bary, Conj. 1858, p. 7G, t. 4, f. 35-37 ; Rabenh.

Flor. Europ. Alg. 1868, p. 150 ; Cooke, Brit. Desm. 1887, p. 5, t. 2, f. 3 ;

Hansg. Prod. Alg. Bohm. 1888, p. 170 ; De Toni, Syll. Alg. 1889, p. 792 ;

Roy & Biss. Scott. Desm. 1893, p. 10 : Liitkem. Desm. Millstattersees

1900, p. 82, t. 1, f. 1-5.
Spondylosium secedens Arch, in Pritcli. Inf. 1861, pp. 719, 724 ; in Quart.

Journ. Micr. Sc. 1871, p. 92 ; Eichler, Mater. Flor. Miedz. 1895, p. 57 ;

West & G. S. West, Alga-fl. Yorks. 1902, p. 95 ; Alg. X. Ireland, 1902,

p. 43, t. 2, f. 19, 20.

Sphcerozosma excavation var. secedens Rabenh. Krypt.-fl. Sachs. 1863, p. 178.
Sph. pycjmceum Hauptfl. Zellm.u. Hiillgallerte Desm. 1888, t. 2, f. 24-26, 30.

Cells small, about as long as broad, but sometimes
slightly longer or shorter, constriction moderately deep,
sinus open and obtuse ; seniicells subelliptical ; lateral
angles rounded, ventral margin slightly convex, dorsal
margin primarily strongly convex, but with a conspicuous

VOL. V. 15

226 BRITISH DESMIDIACE.E.

deep concavity in the middle. Cells attached together
by the projecting parts of the apices to form fragile
filaments, which readily break. Filaments destitute of
a mucous sheath ; cell- wall smooth.

Zygospore globose, provided with simple straight
spines ; rarely irregularly angular, with the angles
produced.

Length 8*5-12 ^ ; breadth 7*5-10 JJL ; thickness 5-6 JJL ;
breadth of isthmus 3'5-6fx; diam. zygosp. without
spines 9-1 0 a ; with spines, 1 5-1 6 \L .

ENGLAND.- -Bog 2 m. S. of Clapham, W. Yorks !
Enbridge Lake, Hants (Roy).

IRELAND. — Near (Plenties, Donegal ! Kylemore, Gal-
way (Arch.). Slieve Donard, Down ! Shores of Lough
Neagii.

SCOTLAND. — Slewdrum, Loch Dawan, and Mosston
Moor in Cromar, Aberdeen (Roy & Biss.}.

Geogr. Distribution. — C4ermany. C4alicia and Austria.
Spain. Scandinavia. Poland. Australia.

7. Spondylosium tetragonum West.
(PI. CLXI, figs. 12-14.)

Sphcerozosma (Spondylosium) pulchdlum Gay, Monogr. loc. Conj. 1884,

p. 79, t. 3, f. 1.

? Sph. bambusinoides Heimerl, Desm. alpin. p. 589, t. 5, f. 1 (form).
Spondylosium tetragonum West, Alg. W. Ireland, 1892, p. 115, t. 19, f. 2 ;

West & G. S. West, Rec. publ. Desm. 1895, p. 65 ; Freshw. Alg. Columbia,

1912, p. 1046, t. 23, f. 55-57.
Sp. Treubii Bernard. Alg. unicell. domaine Malais, 1909, p. 21, t. 1, f. 16.

Cells minute, slightly longer than broad, slightly and
broadly excavated at the isthmus, sides rounded, apex
of semicells truncate ; in vertical view elliptical ; in
side view oblong, very slightly constricted. Cells united
into twisted colonies, destitute of a mucous sheath.

Zygospore unknown.

Length 8'5-lOfji ; breadth 10 pi; thickness 6^;
breadth of isthmus 8 [i .

IRELAND.- -Kylemore, Galway !

Geogr. Distribution.- -France. Switzerland. Finland.
Java. Colombia.

SPONDYLOSIUM. 227

8. Spondylosium pulchellum Arch.
(PL CLXI, figs. 1-3.)

a pulchellum Arch. Suppl. Cat. Desm. 1858, p. 253, t. 21, f. 7 ;
Rabenh. Flor. Europ. Alg. 1868, p. 150; Cooke, Brit. Desm. 1887, p. 6,
t. 2, f. 4; Maskell, Further Notes X. Zeal. Desm. 1888, p. 9, t. 1, f. 2 ;
De Toni, Syll. Alg. 1889, p. 792 ; West. Alg. X. Wales, 1890, p. 7 ; Comere,
Desm. de France, 1901, p. 199, t. 16, f. 8.

Snondylosium pulchellum Arch, in Pritch. Inf. 1861, p. 724, t. 3, f. 10 ;
in Quart. Journ. Micr. Sci. 1866, p. 120 ; Xordst. Xorges Desm. 1873, p. 47;
Arch, in Quart. Journ. Micr. Sci. 1877, p. 191 ; Kirchn. Alg. Schles. 1878,
p. 134 ; Anderss. Sverig. Chlor. 1890, p. 9 ; West, Alg. W. Ireland, 1892,
p. 115 ; Roy & Biss. Scott. Desm. 1893, p. 10 ; West & G. S. West, Alg.
S. England, 1897, p. 492 : Alga-fl. Yorks. 1902, p. 95 ; Alg. X. Ireland,
19023 p. 42 ; G. S. West, Brit. Freshw. Alg. 1904, p. 176, f. 67 A : West
& G. S. West, Alg. Orkneys & Shetlands, 1905, p. 28.

Xphcerozosmasecedens vai. pulchdlum Hansg. Prodr. Alg. Bohm. 1888, p. 170.

Cells very small, about as long as broad, sometimes
longer than broad, constriction fairly deep, sinus linear ;
semicells truncate-pyramidate, inflated at the base,
apex broad and flat, upper angles sharp, almost rect-
angular ; lower angles broadly rounded ; sides gently
concave ; semicells in side view subcircular ; in end
view elliptical ; filaments often long, not twisted,
frequently found attached by a short thick gelatinous
stalk to other aquatic plants.

Zygospore unknown.

Length 12-lou.; breadth 10-11 fj. ; breadth of apex
5[JL ; breadth of isthmus 4*5-6 [/..

ENGLAND.- -Harrop Tarn, Cumberland ! Grisedale
Tarn, Westmoreland ! Adel, W. Yorks, and Strensall, N.
Yorks (W. B. Turn.}. Skipwith and Riccall Commons,
E. Yorks ! Grimspound ! and Dartmoor (Harris],
Devonshire.

WALES. — Snowdon !, Moel Siabod !, and Capel Curig
(Cooke & Wills), Carnarvonshire.

SCOTLAND.- -Ross, Inverness, Aberdeen, Kincardine,
Forfar, Perth ! and Argyle (Roy & Biss.}. Sutherland !
Hoy, Orkneys !

IRELAND.- -Donegal ! Mayo! Galway ! Kerry! Lough
Neagh! Ulster, Minister, Leinster and Connaught
.{Adams).

Geocjr. Distribution- -France. Germany. Galicia and

228 BRITISH DESMIDIACEJE.

Austria. Hungary. Norway. Sweden. Denmark. K"..
and S. Russia. Greenland. New Zealand (var.). United
States.

Several investigators have noticed that this tiny species some-
times occurs attached to filamentous alga?, or to the leaves
of mosses, by means of a very short gelatinous basal stalk.
It is the only species of the genus in which this is known to-
occur, and even here the filaments are so fragile and break
away so easily from the basal attachment that it is usually
observed in a free floating condition. The cells are all alike,
and there is no distinction in their form, whether they are
near the base or the apex of the filament. It seems to occur
more abundantly in Ireland than in any other part of the
British Isles.

Var. pyramidatum West. (PL CLXI, figs. 4, 5.)

82)- pulclidlum var. pyramidatum West & G. S. West, New Brit. Ate. 1893,,
p. 3, f. 8 ; Alga-fl. Yorks. 1902, p. 95.

Semicells more definitely pyramidate than in the
type, sides nearly straight, apex broadly truncate ;
isthmus narrower than in the type.

Length 10-11 [I ; breadth 8'6-9'6pi ; thickness 4'Sp ;
breadth of apex 5*8-5*9 ^ ; breadth of isthmus 2-2*6 {A.

ENGLAND.- -Eiccall Common, E. Yorks.

SPECIES TO BE ENQUIRED INTO.

SPONDYLOSIUM ARMILLATUM Turn. ' Desm. Notes,' 1893, p. 346,
f. 20. A still smaller plant (than Spondylosium monile Turn.
= SP- pygwi&nm, var. monile (Turn.) West), biscoctiform,
centre gently incavate in front view ; side view compressed.
Length 6 (JL ; breadth 3*7 /u ; thickness 2'5 p — Trelleck Common,
Monmouth, Wales.

Genus 24. HYALOTHECA Ehrenb. 1840.

Ehrenb. in Berlin. Monats. 1840, p. 212.
Kiitz. Phyc. Germ. 1845, p. 140.
Ralfs, Brit. Desm. 1848, p. 51.
Kiitz. Spec. Alg. 1849, p. 187.
De Bary, Conj. 1858, p. 76.

HYALOTHECA. 229

Arch, in Pritch. Inf. 1SG1, p. 722.

Rabenh. Flor. Europ. Alg. 1808, p. 151.

Delp. Spec. Desm. subalp. 1873, pp. 23, 47.

Wood, Freshw. A]g. X. Amer. 1873, p. 124.

Kirchn. Alg. Schles. 1878, p. 131.

Wolle, Desm. U. S. 1884, p. 22.

Cooke, Brit. Desm. 1887, p. 7.

De Toni, Syll. Alg. 1889, p. 785.

Wille in Eiigler Xaturl. Pflanzenf. 1890, p. 16.

Comere, Desm. de France, 1901, p. 196.

G. S. West, Brit. Freshw. Alg. 1904, p. 176.

Cells subcylindrical. shorter or longer than broad,

V O

very slightly constricted, semicells trapezoid, sub-
quadrate or oblong, with straight or slightly convex
lateral margins ; cells united by their broadly truncate
apices to form long filamentous colonies, which are
sometimes twisted and almost invariably enveloped in
a gelatinous sheath of some thickness. Chloroplasts
axile, one in each semicell. usuallv with a central

*/

pyrenoid, and several radiating ridges.

Zyuospores globose, smooth, sometimes enclosed in an
irregularly shaped structure consisting of the gamet-
angia united by the broad conjugation tube. Prior to
conjugation the filaments break up into individual cells.

Aplanospores are known in two species of the genus.
They are formed from the ordinarv cells bv the rounding

•/ «/ */

off of the cell contents, which then acquire a strong cell-
wall of their own. The formation of aplanospores is
also accompanied by the total or partial dissociation of
the filament into individual cells.

The genus Hyalotheca is very closely allied to Spondylosium,
from which it is distinguished bv its extremely slight develop-

£j «/ •/

ment of a sinus, and also by the usually circular outline of its
cells in the vertical view. There are 5 British species only, of
which one is abundant and universal in its distribution, whilst
three are amongst the rarest of British Desmids.

1. Hyalotheca dissiliens (Sm.) Breb.
(PL CLXI, figs. 16-27.)

Conferva dissiliens Smith, Ens:!. Botairv, v. 35, 1812, t. 2464.
Desmidium nutcosum Breb. Alg. Falaise, 1835, p. 65, t. 2 ; Menegh. Synops
Desm. 1840, p. 4 ; Ralfs in Ami. Mag. Xat, Hist, 1843, p. 374, t. 8, f. 2.
Giceoprium dissiliens Hass. Brit. Freshw. Alg. 1845, p. 346, t. 83, f. 34.

230 BRITISH DESMIDIACE^E.

Hyalotltcca dissiliens (8m.) Breb. in Ralfs, Brit. Desm. 1848, p. 51, t. 1,
f. 1; Breb. Liste Desm. 1856, p. 118; De Bary, Conj. 1858, p. 70;
Wallich, Desm. low. Bengal, 1860, p. 187 ; Arch, in Pritch. Inf. 1861,
p. 722, t. 2, f. 32, 35 ; Rabenh. Krypt,-fl. Sachs. 1863, p. 179 ; De Notaris,
Desm. Ital. 1867, p. 25, t. 1, f. 1 ; Reinsch, Alg. Frank. 1867, p. 203 ;
Rabenh. Flor. Europ. Alg. 1868, p. 152 ; Wood, Freshw. Alg. N. Amer.
1873, p. 124, t, 12, f. 12 ; Delp. Spec. Desm. subalp. 1877, p. 47 ; Kirchn,
Alg. Schles. 1878, p. 131 ; Wille, Ferskv. Alg. Nov. Semlj. 1879, p. .61 ;.
Gay, Mono. loc. Conj. 1884, p. 79; Wolle, Desm. U. S. 1884, p. 22, t. 1,
f. 3-12, t. 24, f. 26 ; Lagerh. Bidr. Amer. Desm.-fl. 1885, p. 228 ; Cooke,
Brit. Desm. 1887. p. 7, t. 3, f. 1 ; Hansg. Prodr. Alg. Bohm. 1888, p. 168 ;
Boldt, Desm. Gron. 1888, p. 43, t. 2, f. 53 ; De Toni, Syll. Alg. 1889,
p. 785 ; Wille in Engler, Natur. Pflanzenf. 1890, p. 15, f. 9 ; Heinierl,
Desm. Alpin. 1891, p. 588; West, Alg. W. Ireland, 1892, p. 116; Ate.
E. Lake Distr. 1892, p. 6 ; Roy & Biss. Scott. Desm. 1893, p. 9 ; Liitkem.
Desm. Attersees, 1893, p. 538 ; Turn. Freshw. Alg. E. India, 1893, p. 151 ;
Borg. Ferskv. Alg. Ost. Gronl. 1894, p. 32; Schroder, Beitr. Alg. Riesen-
gebirges, 1897, p. 28 ; West & G. S. West, Alg. S. England, 1897, p. 497 ;
G. S. West, Alga-fl. Cambs. 1899, p. 25 ; West & G. S. West, Furth.
Contr. Alg. W. Indies, 1899, p. 284 ; Comere, Desm. France, 1901, p. 190,
t. 16, f. 7 ; West & G. S. West, Freshw. Chlor. Koh Chang, 1901, p. 97 ;
Alg.-fl. Yorks. 1902. p. Ill ; Alg. Ceylon, 1902, p. 195 ; Alg. N. Ireland,
1902, p. 60 : Liitk. Zellm. Desm. 1902, p. 365, t, 18, f. 16, 29, 30 ; Borge,
Alg. erst. Regn. Exped. II, 1903, p. 122 ; G. S. West, Brit. Freshw.
Alg. 1904, p. 176, f. 68, A-D ; West & G. S. West, Freshw. Alg. Orkneys
& Shetlands, 1905, p. 28; Alg. Burma, 1907, p. 225, t. 12, f. 11-15;
Borge, Botan. Notiser, 1911, p. 203 ; Kaiser, Alg. Traunstein Chiemeau,.
1914, p. 153 ; Acton, HyalotJieca dissiliens, 1916. p. 379.

H. tmicosa Kiitz. Spec. Alg. 1849, p. 187.

Cells of medium size, about Ij times broader than
long; constriction extremely small, consisting of a very
slight concavity in the middle of the lateral margins;
cells united by their apices to form long slimy filaments,
constricted at the joints ; apex of semicells broadly
truncate, about as broad as the isthmus, lateral margins
slightly convex ; vertical view circular, sometimes with
2 opposite papilla?, or 3, equidistant (see formse bidentula
and tridentula, infra). Chloroplasts axile, one in each
semicell, with a central pyrenoid and a number of radiat-
ing ridges, star-like in the vertical view. Filaments
usually enveloped in a conspicuous gelatinous sheath,
often as broad as the filament itself.

Zygospores produced after the dissociation of the
filaments into isolated cells, spherical or rounded-oblong,,
smooth, contained in the swollen conjugation tube, to
which the gametangia remain attached.

Length 10-33(j,; breadth 10-39 pi; diam. zygosp.
1 5-25 i.

HYALOTHECA. 231

ENGLAND. — Cumberland ! and in the plankton of
Ennerdale and Derwent Water ! Westmoreland ! (at
2400 feet on Helvellyn) and in the plankton of Brother's
Water and of Codale, Easedale, and Eed Tarns. Lan-
cashire (Ralfs). W., N., and E. Yorks. Cheshire and
Leicester (Roy). Suffolk ! Essex ! Cambs ! Berks !
Warwicks ! (Witts). Worcs ! Gloucester (Ralfs).
Surrey ! Sussex (Ralfs). Kent! Hants! Wilts!

fc/ i/ /

Devon ! (Harris). Cornwall !

WALES. — Common ! (zygospores common and up to
2200 feet on Glyder Each, and at 2700 feet on Glyder
Fawr.

SCOTLAND. — General ! and in the plankton ! Wig-
town (with zygospores) ! Lewis and Harris, Outer
Hebrides ! Orkneys and Shetlands !

«/

Common ! Zygospores abundant ! In the

plankton. Mayo !. Galway and Kerry !

Geogr. Distribution.- France. Germany. Switzerland.
Austria. Hungary. Roumania. Turkey. Italy. Por-
tugal. Norway. Finmark. Sweden. Denmark. Born-
holm. Finland. Poland. X., S.. and Central Russia.
Faeroes. Xova Zembla. Spitzbergen. Greenland.
Siberia. Central China. India. Ceylon. Burma. Siam.
Singapore. Java. Australia. E. and Central Africa.
Azores. United States. X. W. Canada. W. Indies.
Guiana, Colombia. Brazil. Paraguay. Argentine.

/

H. dissilicns is one of the most ubiquitous of Desmids, and
often occurs in great abundance. It is generally distributed in
bogs and ditches, is not infrequent in plankton, and is often
found conjugated. The zygospores also occur as a rule in great
numbers. The broad gelatinous sheath which is almost invari-
ably present is secreted by special pores in the cell-wall, which
are crowded together in a broad band on the lateral walls of
each semicell. The external aperture of these pores is often
closed by a hardened gelatinous structure which renders them
conspicuous, so that the wall appears to be punctate or finely
granulate. This punctate appearance has been noted by several
observers, but it is only due to phenomenon of jelly-secretion.
The end cell of the filament has its free end also covered with

232 BRITISH DESMIDIACEJE.

gelatinous material, which is secreted by a similar group of
pores in the middle part of the apex.

Aplanospores have been observed in this species in material
from Burma (f. bidentula and tridentula) ; vide W. & G. S. West,
'Alg. Burma,' 1907, p. 225, t. 12, f. 11-15. Their formation is
preceded by the dissociation of the filaments into individual
cells. The cells then increase their volume by a growth in length,
becoming ultimately as long as broad. The chloroplasts soon
show signs of disintegration, and then the entire protoplasmic
mass assumes a spherical shape, becomes invested with a thick
cell-wall, and forms a globular aplanospore. The increase in
the length of the cell is often unequal, resulting in an asymmetrical
mother-cell.

The zygospore is usually developed in the middle of the con-
jugation-tube between the two conjugating cells, but occasionally
it may be formed nearer to the one gametangium than the other, or
even entirely within one of them. In this case the gametangium
nearer to or containing the zygote is considered $ (cf. Desmidium
cylindricum, p. 251).

Delponte has distinguished 2 distinct forms of H. dissiliens.

A. var. minor Delp. Filaments usually naked, cells nearly
as long as broad or slightly broader. Length of cells 18 /< ;
breadth 21 ju.

B. var. major Delp. Filaments usually with a sheath, cells
1 J times broader than long, or even broader still. Length 27'2 ^<;
breadth 36 //.

The only British record for var. minor is Capel Curig, N. Wales,
and for var. major, Sutton Park, Warwicks., but it is almost
certain that both are more widely distributed. The sheathless
form of H. dissiliens does not commonly occur however.

The vertical view of the species varies in appearance, in
consequence of which several forms are recognised. The typical
form has an exactly circular vertical view, without projections
of any kind, and is known as forma circularis Jacobs. ('Desm.
Danem.' 1875, p. 212). Formae bidentula and tridentula are as
follows :-

Forma bidentula Nordst. (PL CLXI, figs. 20, 26.)

H. dissiliens f. bidentula Xordst. Xorges Desm. 1873, p. 48, t. 1, f. 22 ;
Lagerh. Bidr. Amerik. Desm.-fl. 1885, p. 228 ; Boldt, Desm. Gronl. 1888,
p. 43 ; Nordst, Freshw. Alg. X. Zealand, 1888, p. 27 ; Hauptfl. Zellm.
u. Hiillgallerte Desm. 1888, p. 8 ; t. 1, f. 5, 9-13, 14, 18, 22, 23, 26-29
and 30 ; West, Freshw. Alg. W. Ireland, 1892, p. 116 ; AVest, Alg. Engl.

HYALOTHECA. 233

Lake Distr. 1892, p. 6 (sep.) ; Roy & Biss. Scott. Desm. 1893, p. 9 (sep.) ;
Borge, Sao Paulo Alg. 1918, p. 77.

The cells are provided with small inflations at the
base of the semicells, which are seen best in the end view
as prominences at the two opposite poles of the nearly
circular cell.

Length 16-33 JJL ; breadth 21-36 p. ; thickness 18-33 JJL.

ENGLAND.- -Near Ditton Farm, Surrey ! Enbridge
and Milford Lakes, Hants (Roy).

SCOTLAND. — Common (Roy & Biss.).

IRELAND.- -Lough Guitane, Kerry !

Geoyr. Distribution. — Germany. Switzerland. Galicia
in Austria. Norway. Sweden. Finland. Nova Zembla.

•

Spitsbergen. Greenland. Burma. New Zealand. Brazil.

This form is probably more general in the British Isles than
would appear from the above localities given, but it is difficult
to recognise except in the end view.

Forma tridentula Nordst. (PL CLXI, fig. 21.)

//. dissiliens f. tridentula Xorclst. Xorges Desm. Ls7.'>. p. 48, t. 1, f. 23;
Boldt, Desm. Gronland, 1888. p. 43 • Xordst. Freshw. Ale. X. Zealand,
1888, p. 27 ; Roy & Biss. Scott, Desm. 1893, p. it : West & G. S. West,
Alg. S. England," 1897, p. 497; Alga-n. Yorks. 1902. p. Ill; Alg. X.
Ireland, 1902, p. 60 ; Alg. Orkneys and Shetland*, 1905, p. 28.

H. dissiliens f. triquetra Jacobs. Desm. Danem. 187"), p. 213, t. 8, f. 29.

Semicells with 3 small basal inflations visible as tiny
mamillse at equal distances in the end view.

Length 18-24 pi ; breadth 26-37 u.

ENGLAND. — Cronkley Fell, N. Yorks ! Sutton Park,
Warwicks ! Esher West End Common, Surrey !
Enbridge and Milford Lakes, Hants (Roy). Wilts !
Halo;avor and Lanliverv Moors, Cornwall !

c^ «/

SCOTLAND. — General ! In the plankton ! Lough near
Cearnabahl, Lewis, Outer Hebrides ! Shetlands !

IRELAND.- -Donegal (zygospores from Lough Nacung)!
Oalway ! Kerry !

Geogr. Distribution. — Galicia in Austria. Hungary.
Italy. Portugal. Norway. Sweden. Finland. Spitz-
bergen. Greenland. India. Burma. New Zealand.
'Colombia. Argentine.

234 BRITISH DESMIDIACE^.

Var. tatrica Eacib. (PL CLXII, fig. 19.)

//. dissiliens var. latrica Eacib. Nonn. Desm. Polon. 1885, p. 64, t. 14, f. 5 j
De Toni, Syll. Alg. 1889, p. 786 ; West, Alg. Engl. Lake Distr. 1892,.
p. 6 (sep.) ; Nehroder, Alg. Versuchsteiche Schles. Fischereiv. Trachen-
berg. 1897, p. 28.

Cells nearly as long as broad, or even up to Ij times
longer than broad, quadrangular, distinctly constricted
at the middle ; semicells about twice as broad as long,,
with convex sides ; forming short filaments, destitute
of a mucous sheath. Cells in end view either perfectly
circular, or of the form bidentula.

Length 16-22[x ; breadth 16-20ri ;

ENGLAND.- -Ha wkshead, Lancashire !

Geogr. Distribution. — Galicia in Austria. Poland.
E. Africa,

Var. hians Wolle. (PL CLXII, figs. 16-18.)

H. dissiliens var. hian-s Wolle, Freslnv. Alg. U. 8. 1887, p. 21, t. 54, f. 14-16 ;.
De Toni, Syll. Alg. 1889, p. 786; West, Alg. W. Ireland, 1892, p. 116;
Alg. Engl. Lake Distr. 1892, p. 6 (sep.) ; West & G. 8. West, Alg. 8. Eng-
land, 1897, p. 497; Alga-fl. Yorks. 1902, p. Ill; Alg. Ceylon, 1902,
p. 195 ; Alg. N. Ireland, 1902, p. 60 ; Alg. Orkneys and Shetland*. 1905,
p. 28 ; Borge, Sao Paulo Alg. 1918, p. 77.

H. Indica Turn. Alg. E. India, 1893, t. 19. f. 18 (only).

Filaments conspicuously constricted at the joints ;
cells usually much broader than long, lateral margins
of cell very convex, with an acute median incision or
notch ; filaments enclosed in a sheath.

Length 12-22[ji ; breadth at broadest part 20-32 \L ;
breadth at apex of semicell 15-24 [ji ; breadth of isthmus
18-26 [i.

ENGLAND.- -Westmoreland ! Lancashire ! Horton in
Eibblesdale, W. Yorks ! Great Shunnor and Cronkley
Fells, N. Yorks ! Esher West End Common, Surrey !

SCOTLAND.- -Lerwick, Shetlands !

IRELAND. --Near Glenties, Donegal! Clifden, Galway!

Geogr. Distribution.--^. Russia. Ceylon. New Zealand.
United States. W. Indies. Brazil.

The turgid cells, very much constricted at their points of
union, and also with their prominent median incision, readily
distinguish this variety from the typical form.

HYALOTHECA. 235

2. Hyalotheca mucosa (Mert.) Ehr.
(PI. CLXII, figs. 1-4.)

Conferva mucosa Mert. in Dilhvyn Brit. Conferva?, 1809, p. 46, t. B ; Aaardh,

Syst. Alg. 1824, p. 90 : Harv. in Hook. Br. Fl. 1833, p. 351.
?? Actinocydus rariabilis Corda in Aim. de Carlsbad, 1840, p. 198, t. ii,

f. 11-14.
Hyalotheca nuicosa Ehr. in Berlin Monatsb. 1840. p. 212; Ralfs, Brit.

Desm. 1848, p. 53, t. 1. f. 2 ; Arch, in Pritch. Inf.' 18(51. p. 722 ; IJabenh.

Krypt.-fl. Sachs. 18(33, p. 179 : De Xot. Desm. Ital. 18(37, p. 26, t. 1, f. 2 ;

Reinsch, Alg. Frank. 1867, p. 204 ; Rabenh. Flor. Europ. Alg. 1868r

p. 152 ; Xordst. Xorges Desm. 1873, p. 48 ; Wood, Freshw. "Ate. N.

Amer. 1873, p. 124 ; Kirchn. Alg. Schles. 1878, p. 131 ; Lagerh. Bidr.

Sverig. Desm. 1883, p. 54 ; Gay, Monogr. loc. Conj. 1884, p. 79, t. 3, f. 2 ;

Wolle, Desm. U. S. 1884, p. 23/t. 1, f. 13 : Hacib. Xon. Desm. Polon. 1885,

p. 64 ; Lagerh. Bidr. Amerik. Desm. 1885, p. 228 : C'ooke. Brit. Desm.

1887, p. 8, t. 3, f. 2 : Hansg. Prodr. Alg. Bohm. 1888, p. 168 ; Hauptfl.

Zellm. u. Hulteallerte Desm. 1888, pp. 63, 104; De Toni, Syll. Ate.

1889, p. 787 ; West, Alg. X. Wales, 1890, p. 7 ; Alg. Engl. Lake Distr.

1892, p. 6; Ate. \V. Ireland, 1892, p. 117; Roy & Biss^ Scott. Desm.

1893, p. 9 ; West & G. S. West, Ate. S. England, 1897, p. 497 ; Borge,
Siissw. Alg. S. Pataffon. 1901, p. 17 :" West & G. S. West. Alga.fl. York*.
1902, p. Ill; Alg." Orkneys and Shetland*, 1905, p. 28; Alg. Third
Tanganyika Exped. 1907, p. 131, t. 4, f. 4. 5 : Alg. Burma. 1907, p. 22«i.

Gloeoprium nnicosuni Ralfs in Ann. MaLr. Xat. Hist. v. 16, 1845, p. 11, t. 3,

f. 6 : Hass. Brit. Freshw. Ate. Is45. p. :U7, t. 83. f. 5, 6.
Hyalotheca Ralfsii Kiitz. Spec. Ate. 1.S49. p. 1S7.
Mixot(''/tin//t anniUare Delj). Spec. Desm. subalp. 187."). p. 50, t. I, f. 13-19.

Cells of medium size, quadrangular, about as long as
broad, or sometimes rather longer, cylindrical, usually
without the faintest indication of a constriction in the
normal resting cell, very slightly or not conspicuously
constricted at the joints, each semicell with 2 parallel
rings of tiny granules just beneath its apex ; vertical
view circular ; chloroplasts axile, one in each semicell,
each with a central pyrenoid and several radiating ridges;
filament enclosed in a very massive gelatinous sheath,

«/

usually of greater thickness than in H. (lissiliens.

Zygospore spherical, or oblong with rounded ends,
membrane smooth and yellowish brown.

Length 16-22 pi; breadth 16-22^; diam. zygosp.
27-30 pi.

ENGLAND. — Plankton of Ennerdale Water, Cumber-
land ! Westmoreland, and in the plankton of Brother's
Water, Grasmere, and Coclale and Easedale Tarns!
W. and X. Yorks ! Essex and Herts (Hassall). War-

•236 BRITISH DESMIDIACE^:.

wicks! (Witts). Surrey! Sussex (Ralfs). Hants! (Ben-
nett). Devon and Cornwall ! (Ralfs).

WALES.- -Llyn Padarn !, Dolbadarn Castle!, Llyn
Idwal!, LlynOgwen! and Capel Curig ! (Cooke & Wills),
Carnarvonshire.

SCOTLAND.- -Inverness !, Aberdeen, Kincardine, Perth !
and Argyle (Roy & Biss.). Sutherland ! Ross ! Lewis
and Harris, Outer Hebrides ! Not uncommon in the
plankton ! Plankton of Bressay, Shetlands !

IRELAND.- -Dungloe and Glenties, Donegal ! Plank-
ton of Mavo ! Ouo-hterard, Derrvclare Lough and in

«/ \f

plankton, Galway ! Muckross, Glen Carragh and in
plankton, Kerry ! Carrantuohill, Cork ! Dublin and
Wicklow (Arch.). Slieve Donard, Down !

Geogr. Distribution.- -France. Germany. Switzerland.
Galicia and Austria. Hungary. Italy. Spain. Portugal.
Norway. Sweden. Bornholm. Finland. Poland. S.
Russia. India. Australia. Central Africa. LTnited States
and Alaska. N. W. Canada. Guiana. Brazil. Patagonia.

This species, although neither so common nor so abundant as
H. dissiliens, is fairly generally distributed in the British Isles.
It is readily distinguished from the latter species by the entire
absence of a constriction, its apical crown of minute granules,
and by its usually thicker sheath.

According to Hauptfleisch, each tiny granule near the apex of
the semicell has in its centre the mouth of a jelly-secreting pore,
and it is by means of these pores that the broad tough sheath
of the filament is produced. The apical surface of each semicell
is also provided with similar pores, but the mouths of these are
not protruded beyond the general level of the surface in the same
way as the lateral ones.

Var. minor Roy & Biss. (PL CLXII, fig. 5.)

H. mucosa var. minor Roy & Biss. Scott. Desm. 1893, p. 9 (sep.) ; West
& G. S. West, Alg. Ceylon, 1902, p. 195, t, 22, f. 20.

Cells relatively narrower than in the type ; filaments
about half the normal thickness.

Length 12'5-U'oy. ; breadth 9-12 ku.

HYALOTHECA. 237

SCOTLAND. — Birsemore Loch, Aberdeen (Roy &
Biss.}.

Geogr. Distribution . — Ceylon.

3. Hyalotheca Indica Turn.
(•PL CLXII, fig. 10.)

Hyalotheca Indica Turn. Freshw. Alg. E. India. 1893, p. 152, t. 22, f. 17"
(not t. 19, f. 18, which is H. dissiliens var. hirnis); West & G. 8. West,
Alg. Ceylon, 1902. p. 195; Further Contrib. Plankton Scott. Lochs,
1905, p.' 505, t. 6, f. 6.

Cells small, a little longer than broad, subcylindrical,
very slightly broader in the middle than at the ends,
with a small but acute median incision ; apex of semi-
cell broad and truncate ; filaments not conspicuously
excavated at the joints ; in vertical view circular ;;
chloroplasts axile, one in each semicell, each with a
central pyrenoid. Filaments enclosed in a gelatinous
sheath.

Zygospore unknown.

Length 10-15*5 IJL ; breadth 9-12 \L ; breadth of apices
7'o-10fJL ; breadth of isthmus 8-10 IL.

ENGLAND.- -Plankton of Easedale Tarn, Westmore-
land !

SCOTLAND.- -Plankton of Loch Fadaghoda, Lewis,
Outer Hebrides !

IRELAND.- -Plankton of small lakes, Clifden to Round-
stone, Galway !

Geogr. Distribution.- -India. Ceylon. Java (var.).

This species bears a superficial resemblance to some forms of
H. dissiliens. From var. hians Wolle of that species it is dis-
tinguished by the relatively broader apices of its cells, the fila-
ments not being so conspicuously excavated at the joints, whilst
from H. dissiliens var. tatrica Racib. it is distinguished by its
smaller size, and by the different form of its constriction, which,
even though very slight, is more abrupt than in that species.
The British examples are somewhat larger than those from India
and Ceylon.

238 BRITISH DESMIDIACE^E.

4. Hyalotheca neglecta Kacib.
(PL CLXII, figs. 11-15; PL CLXIII, figs. 1-4.)

Hyalotheca neglecta Racib. Desm. Tapakoomas, 1895, p. 30, t. 2, f. 2, 3 ;
'West & G. S. West, Alg. S. England, 1897, p. 497 ; Obs. Conj. 1898,
pp. 52, 54, t. 4, f. 22-33; Desm. U. S. 1898, p. 321 ; G. S. West, Brit.
Freshw. Alg. 1904, p. 176, f. 68, E-H ; West & G. S. West, Further
Contrib. Plankton Scott. Lochs, 1905, t. 5, no. 6, f. 1.

Cells of medium size, 2-1—3 times longer than broad,
subcylindrical, with, an almost imperceptible median
constriction, and a slight inflation on either side of it ;
apices broad and truncate ; cells in vertical view
circular, cells closely united to form short filaments,
often enclosed in a broad gelatinous sheath. Cell-wall
minutely punctulate, punctse arranged in transverse rows.
Chloroplasts axile, one in each semicell, typically with
a single central pyrenoid in each, and plate-like, so that
when viewed from the edge it seems very narrow, just
as in Mougiotia.

Zygospores formed after the filaments have dis-
sociated into individual cells, rounded, walls smooth,
but sometimes with two rounded mamillse at opposite
poles.

Length 28-42 [JL ; breadth 11 '5-14^ ; diam. zygosp.
23-28 (JL.

ENGLAND.- -Plankton of Easedale Tarn, Westmore-
land ! Thursley Common, Surrey ! New Forest, Hants
(with zygospores) !

WALES. — Capel Curig, Carnarvonshire ! In the plank-
ton !

SCOTLAND.- -Ehiconich, and in the plankton of Lochs
Shin and Ruar, Sutherland ! Loch Shiel, Inverness !
Plankton of Lochs Fadaghoda, an Sgath and Stranabhat,
Lewis, Lochs Diracleet and Laxadale, Harris, and Loch
nan Eun, N. Uist, Outer Hebrides !

IRELAND.- -Plankton of Gal way !

Geogr. Distribution. — Norway. Ceylon. United States.
Guiana.

This is one of the rarest of Desmids, and might easily be over-
looked owing to its great similarity to other filamentous Conju-

HYALOTHECA. 239

gatse. It is also more frequently found in plankton than in
collections from bogs. Its chloroplasts are rather unusual for
the genus Hyalotheca, although chloroplasts of this type occur,
amongst other Desmidiacese, in the genus Mesotcenium.

In addition to zygospores, the formation of aplanospores has
been observed in this species. The filaments partially dissociate
into individual cells during their formation. The cell-contents
round themselves off, and finally acquire a thick cell-wall, which
is yellowish and distinctly punctate when mature. The aplano-
spores are elliptical with acutely-rounded poles. Thus they are
very different in appearance from the zygospores.

5. Hyalotheca undulata Xordst.
(PL CLXII, figs. 6-9.)

Hyalotheca undulnta Xordst. in Wittr. &• Xordst. Als. exsic. 1879, no. 248,
and in fasc. 21, 1889, p. 33 ; Wolle. Desm. U. S. 1884, p. 23, t. 53, f. 8 ;
De Toni, Syll. Alg. 1889, p. 788 ; West, Freshw. Alg. X. Wales, 1890,
p. 7 (sep.); Alg. \V. Ireland, 1892, p. 117; Roy & Biss. Scott. Desm.
1893, p. 9, t. 1, f. 1 ; West & G. S. West, Some N. Amer. Desm. 1896,
p. 232 ; Freshw. Chloroph. Koh Chang, 1901, p. 96 ; Alg. Ceylon, 1902,
p. 195, t. 22, f. 27 ; Alg. Burma, 1907, p. 226.

H. undulata var. producta Turner, Freshw. Alg. E. India, 1893, p. 152, t. 18,
f. 15.

Cells very small, li-2 times longer than broad, lateral
margins with a broad shallow median indentation, so
that they are biimdulate ; semicells globose-obovate,
with truncate apices ; diameter of isthmus and apex
of semicells about equal ; cells in end view circular ;
chloroplasts axile, one in each semicell, each with a
central pyrenoid and about 4 radiating ridges. The
filaments may or may not be enclosed in a gelatinous
sheath.

Zygospore unknown.

Length 10 -17 '5 pi ; breadth 6-9 ^ ; diam. isthmus =
diam. apices = 4'6-7'5 \L.

WALES. — Capel Curig, Carnarvonshire ! In the plank-
ton !

SCOTLAND.- -Birsemore Loch, Aberdeen (Roy & Biss.).

IRELAND.- -Lough Anna, Donegal ! Roundstone, Bally-
nahinch. and in the plankton, Gal way ! Upper Lake of
Killarney and Lough Guitane, Kerry ! Adrigole, Cork !

240 BKITISH DESMIDIACE^E.

Geogr. Distribution. — Sweden. Finland. India. Ceylon.
Siam. United States.

This is one of the rarest of British Desmids. Its regularlv

o </

undulate margins distinguish it from all other species of the
genus.

Germs 25. DESMIDIUM Ag.

Agardh, Syst. Alg. 1824, p. xv.

Greville, Scott. Crypt, fl. 1828, vol. G, p. 38 ; in Hook, Brit. Fl. 1833; p. 402.

Kiitz. Synops. Diat. 1834, p. 85 (sep.).

Breb. Alg. Falaise, 1835, p. 53 (sep.).

Menegh. Synops. Desm. 1840, p. 2 (sep.).

Kail's in Ann. Mag. Nat. Hist, v. 9, 1842, p. 155 and 253.

Kiitz. Phyc. generalis, 1843, p. 165.

Hassall, Brit. Freshw. Alg. 1845, p. 341.

Kiitz. Phyc. germ. 1845, p. 141.

Ralfs, Brit, Desm. 1848, p. 60.

Kiitz. Spec. Alg. 1849, p. 190.

Nag. Gatt. eiiiz. Ala;. 1849, p. 130.

De Bary, C'onj. 1858, p. 76.

Wallich, Desm. low. Bengal, 1860, p. 186.

Arch, in Pritch. Inf. 1861, p. 723.

Rabenh. Krypt.-fl. Sachs. 1863, p. 180; Flor. Europ. Alg. 18G8, p. 153.

Delp. Spec. Desm. subalp. 1873, p. 56.

Nordst, Norges Desm. 1873. p. 49.

Wood, Freshw. Alg. N. Amer. 1873, p. 126.

Kirchn. Alg. Schles. 1878, p. 132.

Gay, Monogr. loc. Conj. 1884, p. 44.

Wolle, Desrn. U. S. 1884, p. 25.

Cooke, Brit. Desm. 1887, p. 9.

Hansg. Prodr. Alg. Bohm. 1888, p. 171.

De Toni, Syll. Alg. 1889, p. 779.

Wille in Engler, Naturl. Pflanzenf. 1890, p. 14.

Turn. Freshw. Alg, E. India, 1893, p. 149.

Comere, Desm. de France, 1901, p. 200.

G. S. West, Brit. Freshw. Alg. 1904, p. 177.

Didymoprium Kiitz. Phyc. generalis, 1843, p. 165 ; Phyc. germ. 1845,

p. 141 ; Ralfs, Brit. Desm. 1848, p. 55 (in part) ; Kiitz. Spec. Alg. 1849, p.

189 ; Arch, in Pritch. Inf. 1861, p. 723 (in part) ; Rabenh. Krypt.-fl. Sachs.

1863, p. 180 ; Flor. Eur. Alg. 1868, p. 153 ; Delp. Spec. Desm. subalp.

1873, p. 52 ; Wille in Engler, Naturl. Pflanzenf. 1890, p. 15 ; Turn.

Freshw. Alg. E. India, 1893, p. 150 ; [= Subgenus Didymoprium Nordst.

Norges Desm. 1873, p. 49 ; Gay, Monogr. loc. Conj. 1884, p. 44 ; Hansg.

Prodr. Alg. Bohm. 1888, p. 172 ; De Toni, Syll. Alg. 1889, p. 783].
Aptogonum Ehr. Inf. 1838, p. 382 ; Ralfs, Brit, Desm. 1848, p. 63 ; Wallich,

Desm. low. Bengal, 1860, p. 191 ; Arch, in Pritch. Inf. 1861, p. 723 ;

Rabenh. Flor. Eur. Alg. 1868, p. 155; Delp. Spec. Desm. subalp. 1873,

p. 61 ; [= Submenus Aptogonum Nordst. Norges Desm. 1873, p. 50 ;

Hansg. Prodr. Alg. Bohm, 1888, p. 171 ; De Toni, Syll. Alg. 1889, p. 781].

Cells united to form twisting filamentous colonies,
sometimes embedded in a thick mucous sheath ; cells

DESM1DIUM. 241

often extremely depressed, usually much broader than
long, with a distinct but only moderately deep
constriction ; in vertical view either elliptical, usually
with mamillate poles, or 3- or 4-angled ; chloroplasts
axile, one in each semicell, with a massive lobe, con-
taining a pyrenoid, radiating from the centre into each
angle, or sometimes opposite to each face, and with a
pair of plates extending into each angle ; in forms with
an elliptical vertical view the number of pyrenoids is
more variable. The cells are attached to each other
in forms with an elliptical vertical view merely by the
close apposition of ridge-like thickenings on adjacent
apices, and in the angular forms by short truncate
processes projecting from the apices of the cell, one
in each angle. In the latter case there is often a
space of varying size between the apices of adjacent
cells.

Zygospores rounded or ellipsoidal, smooth or some-
times with short flattened conical papilla?.

The genus Desmidium, together with the closely allied follow-
ing genus Gymnozyga and the tropical genus Streptonema, differ
from all other Desmids in their method of cell-division. In
these genera, when a cell is dividing, that part of the cell-wall
where the new and old walls abut on each other develops a ring-
like thickening, which is transformed by further growth into a
sort of imagination of the wall projecting into the old semicell.
As the new semicell develops this plication straightens itself
out. Where the cells are united by their whole apical surface
only one such imagination is formed during cell-division. But
where the union is effected by means of short apical processes
as many imaginations are formed as there will eventually be
processes. The projecting ridges of the new cell- wall are very
conspicuous during cell-division.

There are eight British species of the genus, of which none is
really abundant. These may be arranged as follows :

* Seniicells with well-developed apical feet and cavities, easily
seen, between adjacent cells.

1. D. Aptogonum.

2. D, pseudostreptonema.

VOL. V. 16

242 BRITISH DESMIDIACE^E.

** Ca.vities between cells absent, or not readily visible.
f Semicells angular in vertical view.

3. D. Occident ale.

4. D. Swartzii.

ft Semicells circular or elliptical in vertical view, often
with opposite mamillse.

5. D. cylindricum.

6. D. coarctatum.

7. D. gracileps.

8. D. qiiadratum.

i

1. Desmidium Aptogonum Breb.
(PL CLXIV, figs. 1-3.)

Desmidium Aptogonum Breb. Alg. Falaise, 1835, p. 65, t. 2 ; Menegh,
Synops. Desm. 1840, p. 3 (sep.) ; Kiitz. Phyc. Germ. 1845, p. 141 ;
Spec. Alg. 1849, p. 190 ; De Bary. Conj. 1858, p. 76, t. 6, f. 55, 56 ; Arch,
in Pritch. Inf. 1861, p. 723, t. 3, f. 7, 8; Eabenh. Krypt.-fl. Sachs. 1863,
p. 181 ; Reinsch, Alg. Frank. 1867, p. 206 ; Rabenh. Flor. Eur. Alg.
1868, p. 154; Kirchn. Alg. Schles. 1878, p. 132 ; Wolle, Desm. U.S. 1884,
p. 27, t. 2, f. 6, 7, t. 49, f. 7 ; Cooke, Brit. Desm. 1887, p. 11, t. 5, f . 1 ;
Hansg. Prodr. Alg. Bohm. 1888, p. 172; Hauptfl. Zellm. u. Hiillgall.Desm.
1888, pp. 20, 51, t. 2, f. 6, 10-15 ; De Toni, Syll. Alg. 1889, p. 781 ; West,
Alg. N. Wales, 1890, p. 7 ; Alg. W. Ireland, 1892, p. 117 ; Turn. Freshw.
Alg. E. India, 1893, p. 147; Roy & Biss. Scott, Desm. 1893, p. 9; West
& G. 8. West, Some N. Amer. Desm. 1896, p. 233, t. 12, f. 24 ; Desm.
U. States, 1898, p. 320 ; Comere, Desm. de France, 1901, p. 201, t. 16,
f. 10 ; West & G. S. West, Alga-fl. Yorks. 1902, p. 110 ; Alg. Ceylon, 1902,
p. 193 ; Alg. Burma; 1907, p. 226 ; Georgev. Desm. Macedon. 1910,
p. 237 ; Borge, Sao Paulo Alg. 1918, p. 75.

Aptogonum Desmidium Ralfs, Brit. Desm. 1848, p. 64, t. 32, f. 1 a-d ;
Breb. Liste Desm. 1856, p. 119 ; Delp. Spec. Desm. subalp. 1873, p. 61,
t. 3, f. 1-5 ; Hustedt, Desm. et Bac. Tirol, 1911, p. 341.

Desmidium Swartzii Wallich, Desm. low. Bengal, 1860, p. 189, t. 7, f. 1, 4.

Desmidium Swartzii var. amblyodon West & G. S. West, Alg. Madagascar,
1895, p. 43, t, 9, f. 34, 35.

Cells of medium size, about twice as broad as long,
constriction not deep, but open and acute ; semicells
narrowly oblong, lateral angles broadly rounded, apex
broad and concave in the middle, but produced at the
angles to form fairly long connecting processes, so that
a cavity of considerable size is left between the ad-
jacent cells ; in end view usually triangular, sometimes
quadrangular, angles very broadly rounded, sides con-
cave ; chloroplasts axile, one in each semicell, with a
massive lobe radiating from the centre into each angle,
and a pyrenoid embedded in each mass. Filaments

DESMIDIUM. 243

often long and twisted, usually destitute of a gelatinous
sheath.

Zygospores large, smooth and subspherical, produced
after the partial or total dissociation of the filaments
into individual cells.

Length 13-18 (u : breadth 26-30 u ; breadth of
isthmus 21-24 UL; breadth of apices 21-24 pt; diam.
zyo-osp. 18-26tJL.

ENGLAND. — Ambleside (Kalfs), Loughrigg !, Scan-
dale !, Bowness ! (Bissett) and in the plankton of
Windermere !, Westmoreland. Strensall (W. B. Turn.),
and Pilmoor !, X. Yorks.

WALES. — Capel Curig ! (Cooke & Wills), Llyn Padarn!,
Llyn Idwal !, and in the plankton !, Carnarvonshire.
Llyn Coron. Anglesey ! Dolgelly. Merioneth (Rolfs}.

SCOTLAND.- Xot common ; Sutherland !, Aberdeen,
Kincardine. Forfar, Perth, Argyle and Fife (Roy &
Biss.). Plank- ton of Loch Ruar, Sutherland !, Lochs
Cuthaig and Fadaghoda, Lewis !, Loch Laxadale, Harris !,
and Loch Nan Kun. N. Uist. Outer Hebrides !

IRELAND.- -Ball ynahinch, and Roundstone, Galway !

Geocjr. Distribution. -France. Germany. Switzer-
land. Galicia and Austria. Turkey. Italy. Norway.
Sweden. Denmark. Finland. Japan. India. Ceylon.
Burma. Java. Australia. Madagascar. Sandwich
Isles. United States. Brazil. Ecuador. Colombia.

D. Aptogonum is readily distinguished from all other British
species by the large and distinct spaces between adjacent cells.
It is not at all common, but occurs in plenty in the bogs near
Capel Curig Lake, Carnarvonshire.

Var. Ehrenbergii Kiitz. (PL CLXIV, figs. 4, 5.)

Odontella Desmidlum Ehr. Inf. 1838, p. 153. t. 16, f. iv.

Aptogonum Desmidlum var. ft Ralfs, Brit. Desm. 1848, p. 64, t. 32, f. 1,

e-h.
Desmidlum Aptogonum var. Ehrenbergii Kiitz. Spec. Alg. 1849, p. 190 ;

Rabenh. Flor. Europ. Alg. 1868, p. 154 ; Hansgirg, Prod. Alg. Bohrn.

1888, p. 172; De Toni, Syll. Alg. 1889, p. 781 ; West & G. S. West, Some

N. Amer. Desm. 1896, p. 233, t. 12, f. 23 ; Alga-fl. Yorks. 1902, p. 110.
Aptogonum diagonum Delp. Spec. Desm. subalp. 1873, p. 64, t. 3, f. 6-10.

244 BRITISH DESMIDIACE^E.

Filaments flattened and not twisted, cells in vertical
view oblong with rounded poles, and sides slightly
concave.

Length 14-19 pi; breadth 25-32'5 pt : breadth of
isthmus 22-24 [ji ; breadth of apices 19-28 pi.

ENGLAND. — Strensall Common, N. Yorks !

SCOTLAND.- -Rare. Pools near Birsemoor Loch, Aber-
deen ; near Banchory, Kincardine (Roy & Biss.).

Geogr. Distribution. France. Germany. Italy.
Sweden. Denmark. United States.

Var. acutius Nordst. (PL CLXIV, fig. 6.)

Desmidium Aptogonum var. acutius Nordst. Alg. Sandvic. 1878, p. 11,
t. 1, f. 21, 22; De Toni, Syll. Alg. 1889, p. 782; West, Alg. Engl.
Lake Distr. 1892, p. 7 ; West & G. S. West, Alga-fl. Yorks. 1902, p. 110 ;
Hirn, Desm. Finnland, 1903, p. 14.

Lateral angles in the front view not broadly rounded,
but slightly retuse in the upper part, so that a subacute
angle points towards the apex of the semicell ; in other
respects similar to the type ; triangular or quadrangular
in the vertical view.

Length 16-23^; breadth 32-43 pi ; breadth of
isthmus 26-34 [JL ; breadth of apices 26-34 \i.

ENGLAND. — Bowness, Westmoreland ! Pilmoor, N.
Yorks !

Geogr. Distribution. — Galicia in Austria. Finland.
Java. Australia. Sandwich Isles. United States.

2. Desmidium pseudostreptonema W. & G. S. West.

(PL CLXV, figs. 5, 6.)

Desmidium pseudostreptonema West & G. S. West, Alg. Ceylon, 1902, p. 193,
t. 22, f. 35-37 ; Compar. Study Plankton Irish Lakes, 1906, p. 104, t. 11,
f. 23.

Cells of medium size, somewhat compressed, 1^-2
times broader than long, deeply constricted, sinus
narrow, gradually inflated very slightly towards the
apex ; semicells transversely and narrowly oblong,
sides rounded, apex rather convex, with short connect-

DESMIDIUM. 245

ing processes : in vertical view triangular or bilobed,
with a slight constriction beneath each angle, angles
rounded, slightly produced, sides straight, or slightly
convex.

Zygospore unknown.

Length 17-21 ^ ; breadth 31-35 \L ; breadth of
isthmus 13-5-22 pi ; breadth of apices 14-15'opi.

IRELAND.- -Plankton of small lake between Clifden
and Eoundstone, Galway.

Geogr. Distribution. Finland. Norway. Ceylon.
Australia.

This plant presents a great similarity in appearance to Spondy-
losimn pulchrum Arch., especially the bilobed form. The short
connecting processes on the apices of the semicells are, however,
sufficient to distinguish it readily from that species. Moreover,
the lateral lobes of the semicells are different from those of any
form of Sp. pulchrum.

It has also a considerable resemblance to Streptonema trilo-
batum Wallich, but differs entirely in the nature of the connections
between the cells, which are those of a true Desmidium. A gap
of some considerable size is generally evident between the apices
of any two contiguous cells. The filaments are usually enveloped
in a thick mucous sheath.

3. Desmidium occidentale W. & G. S. West,
(PL CLXIV, fig. 11.)

Desmidium occidentale West & G. S. West, Further Contrib. Plankt. Scott.
Lochs, 1905, p. 505, t. 6, f. 3, 4 ; Borge, Sao Paulo Alg. 1918, p. 75, t. 6,
f. 12.

Cells of medium size, 1^ times broader than long,
slightly constricted, sinus narrow, sublinear ; semicells
oblong semielliptical, lateral margins gently biundulate,
angles rounded, apex truncate-convex, with extremely
short connecting processes ; cavities between the cells
small or wanting ; in vertical view triangular, sides
nearly straight or slightly convex, angles slightly pro-
duced and rounded. Chloroplasts axile, one in each

246 BRITISH DESMIDIACE^E.

semicell, with a central pyrenoid. Filaments twisted,
with or without a mucous sheath.

Zygospore unknown.

Length 25 '5-28 p ; breadth 32'5-38'5M, : breadth of
isthmus 23-28*5 [JL ; breadth of apices 21-25'5^.

SCOTLAND.- -Plankton of Loch Fadaglioda. Lewis,
Outer Hebrides !

Geogr. Distribution. — Brazil.

This species, although occurring abundantly in the plankton
of Loch Fadaghoda, has not been observed from any other
locality in Britain. It is distinguished from D. Swartzii by the
proportionately greater length of its cells, and by the shortened
and more rounded lateral angles of the semicells. The vertical
view is likewise more robust, and the sides are convex (not con-
cave as in D. Swartzii). There is usually no trace of a space
between the apices of adjacent cells, but it may sometimes be
detected with high magnification.

4. Desmidium Swartzii Ag.
(PL CLXIII, figs. 5-8.)

Diatoma Sivartzii Agardh, Disp. A]g. 1812, p. 38.

Desmidium Sicartzii Agardh, Syst. Alg. 1824, p. 9; Grev. Scott. Crvpt.
Fl. 1827, v. 5, t. 292, v. 6, p. 32 ; in Hook. Brit. Fl. 1833, p. 402 ; Ktitz.
Synops. Diat. 1834: p. 85 (sep.); Breb. Alg. Falaise, 1835, pp. 53, 267,
t. 2, 5 ; Menegh. Synops. Desm. 1840, p. 203 ; Ralfs in Ann. Mag. Nat.
Hist. v. 11, 1843, p. 375, t. 8, f. 3 ; ibid. v. 15, 1845, p. 405 ; Hass. Brit.
Freshw. Alg. 1845, p. 344, t. 83, f. 7, 8 ; Kiitz. Phyc. Germ. 1845, p. 141 ;
Ralfs, Brit. Desm. 1848, p. 61, t. 4 ; Kiitz. Spec. Alg. 1849, p. 190 ; Nag.
Gatt. einz. Alg. 1849, p. 131, t. 8 D ; Breb. Liste Desm. 1856, p. 119;
De Bary, Conj. 1858, p. 76, t, 6, f. 57 ; Arch, in Pritch. Inf. 1861, p. 723 ;
Rabenh. Krypt.-fl. Sachs. 1863, p. 180; Reinsch, Alg. Frank. 1867,
p. 205 ; Rabenh. Flor. Europ. Alg. 1868, p. 154 ; Delp. Spec. Desm.
subalp. 1873, p. 56, t, 2. f. 8-20 ; Kirchn. Alg. Schles. 1878, p. 132 ;
Gay, Monogr. loc. Conj. 1884. p. 80. t, 3, f. 3 ; Wolle, Desm. U. S. 1884,
p. 26, t. 2, f. 1-5 ; Cooke, Brit, Desm. 1887, p. 10, t. 5, f. 2 ; Hauptfl.
Zellm. u. Hiillgallerte Desm. 1888, p. 191, t. 2,f. 1-5. 7-9 ; Hansg. Prodr.
Alg. Bohm. 1888, p. 171 ; Nordst, Freshw. Alg. N. Zealand, 1888, p. 25;
De Toni, Svll. Alg. 1889. p. 780 ; West, Alg. N. Wales, 1890, p. 7 (sep.) ;
Alg. W. Ireland, 1892, p. 117 ; Alg. Engl. Lake Distr. 1892, p. 7; Roy
& Biss. Scott. Desm. 1893, p. 9 (sep.) ; West & G. S. West, Alg. S. Eng-
land, 1897, p. 497 ; Comere, Desm. de France. 1901, p. 200, t. 16, f. 11 ;
West & G. S. West, Alga-fL Yorks. 1902, p. 110 : Alg. N. Ireland, 1902,
p. 59 ; G. S. West, Brit. Freshw. Alg. 1904, p. 178, f. 69 A ; West & G. S.
West, Alg. Burma, 1907, p. 226 ; Georgev. Desm. Wlasina See, 1909,
p. 190 ; Desm. Macedonia, 1910. p. 237 ; Hustedt, Desm. et Bacill. Tirol,
1911, p. 342 ; Kaiser, Alg. Traunst, u. Chiem. 1914, p. 154.

DESMIDIUM. 247

Filaments triangular, twisted, usually destitute of a
conspicuous gelatinous sheath ; cells large, about 2J
times broader than long, constriction moderately deep,
sinus linear towards its apex, opening more widely ;
semicells narrowly oblong, lateral margins usually
somewhat obliquely truncate, with the upper angle of
the truncate margin conspicuously protruded towards
the apex of the semicell, the lower angle more rounded ;
apex of semicell broadly truncate, with a short connect-
ing process at each angle of the cell ; middle of apex
very slightly concave ; spaces between the cells not
visible, or recognised only with difficulty ; vertical view
triangular, angles acutely rounded, sides slightly con-
cave ; chloroplasts axile, one in each semicell, witli
two massive lobes radiating from the centre into each
angle of the semicell, and a large pyrenoid opposite each
face.

( Zygospores smooth and oval.

Length 1 2-20 pi ; breadth 37-50 JJL ; breadth of
isthmus 30-42-5 [/. ; breadth of apices 30-41 \L ; length
of zygospore 28-36 p ; breadth 20-28 (i.

ENGLAND. — Cumberland ! Westmoreland, at 2400 ft.
on Helvellyn. and in the plankton of Grasmere ! Lan-
cashire ! (Rolfs). W. and N. Yorks ! Essex (Hassall).
Warwick's! (Wills). Berks (Griffiths). Surrey! Sussex
(Ralfs). Hants ! (Bein/cff). Dartmoor, Devon (Harris)
Cornwall !

WALES. — Capel Curig !, Llyn Idwal !, and in the
plankton !, Carnarvonshire. Llyn Coron, Anglesea !
Dolgelly, Merioneth (Ralfs). Swansea, Glamorgan

(Ralfs).

SCOTLAND. General ; zygospores at Tomacher,
Aberdeen (Roy & Biss.). In the plankton ! Bute !
Harris, Outer Hebrides !

IRELAND. - -Donegal ! Mayo! Gal way ! Kerry!
Dublin and Wicklow (Arch.). Meath (Ralfs).

Geogr. Distribution.- -France. Germany. Switzer-
land. Galicia and Austria. Hungary. Servia. Eon-
mania. Turkey. Italy. Spain. Portugal. Norway.

248 BRITISH DESMIDIACE/E.

Sweden. Denmark. Finland. Poland. Central,
N., and S. Russia. Greenland. Japan. India.
Burma. Australia. New Zealand. Central Africa.
Nova Scotia. United States. Colombia. Brazil.
Paraguay.

D. Swartzii is the commonest species of Desmidium. It lias
a very extensive distribution, and sometimes occurs in
abundance.

There has been some confusion with regard to the zygospores
of this species. Ealfs, in 1848, figured certain spores which he
supposed had been formed each from the contents of a single cell.
Various other authors have published from time to time figures
quite similar to that of Ralfs, under the description of zygospores.
Archer in ' Quart. Journ. Micr. Sci.' v. 7, 1867, p. 296, reports
that he had observed conjugation in this species, and that Ralfs"
figure was quite accurate, but that the earlier observer was wrong
in supposing that the spores were formed each from a single cell.
Archer states that the conjugating filaments apply themselves
so closely to each other that it is very difficult to distinguish
that there really are two there. Archer had quite satisfied him-
self, however, that this was so. Crowe, in ' Quart. Journ. Micr.
Sci.' 1874, p. 105, again supported Archer's statement. Further,
Delponte (' Spec. Desm. Subalp.' 1873, t. 2, f. 12) figures spores
which he says are formed by the conjugation of two cells, and
these are quite similar to those of Ralfs. In view of this evi-
dence, together with the fact that if Ralfs' figure represents one
filament, and not two, it is of extraordinary large diameter, it
seems highly probable that the figures of Ralfs, and similar ones
of other authors, may be considered to represent the zygospores
of this species, with varying degrees of accuracy, but further
corroboration of this is certainly desirable.

Var. quadrangulatum (Ralfs) Roy. (PI. CLXIII,

figs. 9, 10.)

D. quadrangulatii in Ralfs in Ann. Mag. Nat. Hist. 1845. p. 405, t. 12, f. 9 ;
Brit. Desm. 1848, p. 62, t. 5 ; Arch, in Pritch. Infus. 1861, p. 723, t. 2,
f. 37 ; Rabenh. Flor. Eur. Alg. 1868, p. 155 ; Delp. Spec. Desm. subalp.
1873, p. 60, t. 2, f. 21-27 ; Wolle, Desm. U. S. 1884, p. 27, t. 2, f. 13, 14 ;
Cooke, Brit. Desm. 1887, p. 11, t. 5, f. 3 ; Comere, Desm. de France,
1901, p. 200, t, 16, f. 13 ; Borge, Alg. erst. Regnel. Exp 1903, p. 122,
t. 5, f. 24; Hustedt. Desm. et Bacill. Tirol, 1911, p. 342; Borge, .Sao
Paulo Alg. 1918, p. 75.

DESMIDIUM. 249

D. qua rlfiTifj ultra Kiitz. Phyc. gerni. 1845, p. 141 ; De Toni, Syll. Als. 1889,
p. 780.

/•;// var. f/»f;tJr<i ny/il«f/i t/i Roy & Biss. Scott. Desni. 1894, p. 9 ;
G. s. West, Alg. X. Ireland, 1902, p. oil.

Differs from the typical form only in its quadrangular
vertical view, and consequent greater relative breadth
in the front view.

Zygospore elliptical ; inner layer of membrane tawny.

Length 24'8 ?JL ; breadth 57 '6-60^ ; length of zygo-
spore 47 \j. : breadth 32'5 u.

ENGLAND. — Ambleside (Rcdfs) and Loughrigg (Ben-
nett), Westmoreland. Penzance and Tremethick Moor,
Cornwall (Rolfs ; M<u'<ii'<iud).

SCOTLAND.- -otston Moss; Heughhead near Aboyne,
and Blackmoss in Cromar, Aberdeen (Rolfs ; Roy <C*
Biss.). Braemar, Aberdeen !

IRELAND. — Slieve Donard. Down !

('COf/r. Dixlt'ilnili<ni.- -France. Germany. Switzerland.
Austria. Italv. Poland. Australia. E. Africa. Mada-

i

United States. Colombia. Brazil. Paraguay.

Var. amblyodon (Itz.) Eabenh. (PL CLXV, % 7.)

hi.-iiiiiduni' nntbbjrnlni Itz. iii llalx-nh. Bacill. Sachs, fasc. 7, 1852, no. »io,
t. v, f. (i.l.

I). Swartzii var. amblyodtm Halx-nh. Krypt.-fl. Sa.-hs. 1863, p. 181; Flor.
Europ. Alsr. 1868, p. 1.14; De Toni, Syll. A1-. 1889, p. 780; West,
Freshw. Alg. Maine, 1891, p. 354 ; Borge, Sao Paulo Alg. 1918, p. 75.

Cells with lateral angles not obliquely truncate, but
distinctly and broadly rounded. Filaments often en-
closed in a mucous sheath.

Length 15-20;ji ; breadth 32-50^; breadth of
isthmus 25-45 (i.

IRELAND. --Xear Ballynahinch, Galway !

Geogr. Distribution. — Germany. Sweden. United
States. Brazil.

5. Desmidium cylindricum Grev.
(PL CLXIV, figs. 7-10.)

Desmidium cyUndncum Grev. Scott. Crypt. Fl. 1827, vol. v, t. 293, vol. vi,
p. 38 ; in Hook. Brit. Flor. 1833, p. 402 ; Kiitz. Synops. Diat. 1834,
p. 86 ; Menegh. Synops. Desni. 1840, p. 4 (sep.) ; Ralfs in Ann. Mag.

250 BRITISH DESMIDIACE^.

Nat. Hist. v. 11, 1843, p. 373, t. 8, f. 1 ; Hass. Brit, Freshw. Alg. 1845,
p. 342, t. 83, f. 1, 2 ; Kirchn. Alg. Schles. 1878, p. 132 ; Wolle, Desm.
U. S. 1884, p. 25, t. 3, f. 1-4, t. 24, f. 25 ; Cooke, Brit. Desm. 1887, p. 9,
t. 4, f. 2 ; Hansg. Prodr. Alg. Bohm. 1888, p. 172 ; De Toiii, Syll. Alg.
1889, p. 783; West, Alg. W. Ireland, 1892, p. 117; Liitkem. Desm.
Attersees, 1893, p. 538 ; West & G. S. West, Some X. Amer. Desm.
1896, p. 233, t. 12, f. 29 ; Obs. Conj. 1898, p. 52 ; Comcre, Desm. France,

1901, p. 201, t. 16, f. 9 ; Ltitkem. Zellmembr. Desm, 1902, p. 361, t. 19,
f. 7 ; West & G. S. West, Alga-fl. Yorks. 1902, p. 110 ; Alg. N. Ireland,

1902, p. 60 ; Alg. Ceylon, 1902, p. 194 ; G. S. West,. Brit. Freshw. Alg.
1904, p. 177, f. 69 C f Borge, Sao Paulo Alg. 1918, p. 74.

Arthrodesmus ? cylindricum Ehr. Inf. 1838, p. 142.
Hyalotheca cylindricum Ehr. in Berlin Monatsb. 1840, p. 212.
Desmidium compressum Corda in Aim. de Carlsbad, 1840, p. 18.
Didymoprium GrevilUi Kivtz. Phyc. generalis, 1843, p. 166 ; Phyc. Germ.

1845, p. 141 ; Ralfs, Brit. Desm. 1848, p. 57, t, 2 ; Kiitz. Spec. Alg.

1849, p. 189; Breb. Liste Desm. 1856, p. 118: Arch, in Pritch. Inf.

1861, p. 723; Pxabenh. Krypt.-fl. Sachs. 1863, p. 180; Reiiisch, Alg.

Frank. 1867, p. 207 ; De Not. Desm. Ital. 1867, p. 27, t. 1, f. 3 ; Rabenh.

Flor. Europ. Alg. 1868, p. 153 ; Delp. Spec. Desm. subalp. 1873, p. 52,

t, 1, f. 20-28 ; Hauptfl. Zellm. u. Hullgallerte Desm. 1888, p. 16 and 50,

t. 1, f. 39-60 (sep.); Hustedt, Desm. et Bacill. Tirol, 1911, p. 342;

Kaiser, Alg. Traunst. u. Chiemgau, 1914, p. 154.
D. cylindricum Ralfs in Ann. Mag. Nat. Hist. v. 16, 1845, p. 10. t. 3, f. 4 ;

Turn. Alg. E. India. 1893. p. 150.

Desmidium Grcnllll De Bary, Conj. 1858, p. 76r t. 4, f. 30-31.
D. (Didymoprium) cylindricum Nordst. Norges Desm. 1873. p. 49.

Cells large, about 2-21 times broader than long,
constriction slight, sinus linear ; semicells very short,
pyramidate- truncate, basal angles acutely rounded,
lateral margins gently biundulate ; apex broad and
truncate : cells in vertical view elliptical with a rounded
mamilla-like protuberance at each pole ; chloroplasts
axile, one in each semicell, usually with four massive
radiating lobes, in each of which is a pyrenoid ; cells
united by their broad, flat apices to form twisting fila-
ments, with a thickened protruding rim between each pair
of cells ; filaments usually enclosed in a gelatinous sheath.

Zygospores formed after the dissociation of the fila-
ment into individual cells ; large and smooth, globose
or sub globose, contained in one of the conjugating
cells, the other remaining attached.

Length about 24 u ; greatest breadth 41-56 \L ;
breadth of isthmus 45-47 [JL ; breadth of apices 26-40 ;JL ;
thickness 25-38 u. ; diam. zvgosp. 26-40 u. [Much

1 »/ o -L

larger specimens sometimes occur, bub exact measure-
ments of such individuals were not available.]

DESMIDIOI. 251

ENGLAND.- -Loughrigg, AYestmoreland ! Adel Bou,
W. Yorks, and Strensall, X. Yorks (TF. B. Turn.).
War wicks ! Thursley Common, Surrey ! New Forest,
Hants ! Dartmoor, Devon (Harris). Cornwall ! (Mar-

WALES. — Capel Curig (Cooke d* Wills) and Bettws-y-
coed (Roy), Carnarvonshire.

SCOTLAND. — General ; zygospores from Slewdrum in
Birse (Roy & Biss.).

IRELAND. Donegal (zygospores from Dungloe) !
Achill Isle. Mayo ! < la I way (zygospores from Ballyna-
binch) ! Kerry ! Dublin and Wicklow (Arch.).

(icon r. Distribution.- -France. < Germany. Switzer-
land. Galicia and Austria. Italy. Xorway. Sweden.
Denmark. Finland. Poland. X. and S. Russia.
India. Ceylon. Australia. Dnited States. Guiana.
Colombia. Brazil. Para^uav.

O «

D. ctflin<lririnn. although one of the most frequent of all the
species of the genus, and at the same time fairly widely distri-
buted, is rarely abundant. It is one of the largest species, and
is easily recognised by its short broad cells with their simple
apical attachment, and the elliptical vertical view, with a small
mamilla at opposite poles. Raciborski has seen a triradiate
form of the species, in which the end view has three equidistant
mamillse on the nearlv circular outline.

V

The most peculiar and important fact about D. cylindricum
is that its zygospore is formed within one of the conjugating
cells. This is the only known Desmid in which the reproduction
is normally of such a high type that the conjugating cells can be
distinguished definitely as £ and $ gametangia, although the same
thing is known to occur occasionally as an abnormality in Hyalo-
tlicca dissiliens. It is supposed that in this phenomenon the
method of reproduction of the immediate ancestors is disclosed,
i. e. the ancestors of the Desmidieae were filamentatous, and had
a well differentiated type of sexual reproduction. In the evolu-
tion of the Desmidiea3 the acquisition of the unicellular condition
and the development of a highly complicated morphological
structure has gone hand in hand with the degeneration of the
form of reproduction, so that the former high type only remains
in the above-mentioned cases.

252 BRITISH DESMLDIACEJ5.

6. Desmidium coarctatum Nordst.
(PI. CLXV, figs. 1, 2.)

De&midium (Didymoprium) coarctatum Nordst. Botan. Notiser, 1887, p. 155.
D. coarctatum Nordst. Freshw. Alg. N. Zealand, 1888, p. 25, t. 2, f. 3 ; De

Toni, SylL Alg. 1889, p. 785 ; Borge, Austral. Susswasserchl. 1896, p. 8 ;

W. & G. S. West, Some N. Ainer. Desin. 1896, p. 233 ; Nordst. Index

Desm. 1896, p. 76 ; W. & G. S. West, Desm. U. States, 1898, p. 321, f. 7 ;

Freshw. Alg. Ceylon, 1902, p. 194 ; Playfair, New S. Wales Census, 1917,

p. 240.

Filaments flattened, twisted, cells in front view ellip-
tical, about li times broader than long, with a slight
median constriction, sinus linear, basal angles of semi-
cell acutely rounded, lateral margins slightly undulate ;
apex of semicell about -i- its diameter ; lateral view of
cell quadrangular, with the faintest indication of a
median constriction ; vertical view narrowly elliptical
with prominent rounded mamillse at the opposite
poles. Cell- wall with longitudinal rows of minute
punctse ; chloroplasts axile, one in each semicell, each
with a central pyrenoid.

Zygospore unknown.

Length 25-34 \L ; breadth 34-38 fji ; breadth of isth-
mus 33 [L ; breadth of apex 12-14 ^ ; thickness 24-26 JJL.

Geogr. Distribution.- -Finland. Ceylon. Australia.
New Zealand. United States.

Var. cambricum. (PL CLXV, figs. 3, 4.)

D. coarctatum var. cambricum West, Alg. N. Wales, 1890, p. 7, f. 2 ; W.
& G. S. West, Further Contr. Plankt. Scott. Lochs, 1905, p. 505, t. 4,
no. 5, f. 1.

Differs from the type in its different proportions and
in the broader apices of the cells.

Length 22 '5 \L ; breadth 40-45 y. ; breadth of isthmus
35-37'5 LI ; breadth of apex 17'5-20[Ji ; thickness 32-

WALES. — Capel Curig, Carnarvonshire ! In the plank-
ton !

SCOTLAND. — Plankton of Loch Fadaghoda, Lewis,
Outer Hebrides !

DESMIDIUM. 253

The type form of this species has not yet been recorded for
this country, and var. cambricum is extremely rare. Both the
typical form and the variety seem to be subject to considerable
variation in the relative proportions of their cells, and the two
examples of var. cambricum figured present a considerable differ-
ence of habit ; cf. PL CLXV, figs. 3, 4. The example figured
from Loch Fadaghoda (fig. 4) seems to conform more nearly to
the typical form in the proportions of its cells, but differs greatly
in its chloroplasts. Typical D. coa rotation has only one pyrenoid
in the centre of its axile chloroplast. which has about 12 ridges or
radiating plates, whilst the specimens of var. c'linbri'-nni from
Loch Fadaghoda had a distinctly 1-lobed axile chloroplast,
with a pyrenoid in each lobe. It is to be di^iivd that these
forms should be examined more thoroughly with regard to the
chloroplasts.

7. Desmidium gracileps (Xordst.) Lagerh.
(PI. CLXYI, fig. 5.)

/// var. f//v/.'//^/x Xordst. in \Viltr. *.V X..r.lst. Al'_r. exsic.

no. 3»>7, 1SSO.

D. fjnicihji* La^erh. Bidr. Anu-r. I >t.-sm.-fl. 1885, p. 2:28, t. 21. f. :5 : Xnrd-i.

ML'. X. Zealand, 1888, p. 25; I >e Toni, Syll. Alg. 1889, p. 784; Borg.

Desm. Brasil. 18! H>. p. 2.'> ; Turn. Alg. E. India. !«!>:}, ]». ir.o : \\. & G. 8.

\\Vst, Al.Lf. C'eyl.»ii. l!*n-_>. j,. p.. 4 ; Srott. Fresh- . I'Jankt. 1, 1!»03, p. .',.-,2 ;

Borge, Sao Paulo »Sii.-<\\a<-«-ralL.r. 1918, ]>. 74.

Cells in front view rotund, about as long as broad,
constriction slight, sinus narrow ; semicells shortly
pyramidate-truncate, lateral margins biundulate, basal
angles acutely rounded, apex truncate ; side view of
cell quadrate, rather longer than broad, lateral
margins slightly concave. Chloroplasts axile, one in
each sernicell, with a central pyrenoid, and 6-8 radiating
plates.

Zygospore subrectangular, provided with a number
of short, stout nodules at the two opposite ends only,
smooth in the middle part.

Length 18-24 (JL ; breadth 21-26 ^ ; breadth of
isthmus 16-20(jt ; breadth of apex 9-11 [i ; thickness
16-18 \L ; length of zygosp. 26-30 ^ ; breadth 22-24 [i ;
length of spines about 3-4 ku. ; breadth of spines about
2-5 i.

254 BRITISH DESMIDIACE^:.

SCOTLAND.- -Plankton of Loch nan Eun, N. Uist, and
Loch Fadaghoda, Lewis, Outer Hebrides !

Geogr. Distribution.- -India, Ceylon. New Zealand.
United States. Brazil.

8. Desmidium quadratum Nordst.
(PL CLXVI, figs. 6, 7.)

Desmidium (Didymoprium) quadratum Nordst. Norges Desm. 1873, p. 49,

t. 1, f. 24.
I), quadratum Arch, in Journ. Bot, 1874, p. 92 ; Wolle, Desm. U. S. 1884,

p. 26, t. 49, f. 5 ; Lagerh. Bidr. Amer. Desm.-fl. 1885, p. 227, t. 27, f. 1 ;

De Toni, Syll. Alg. 1889, p. 784 ; Roy & Biss. Scott. Desm. 1893, p. 9 ;

W. & G. S.'West, Some N. Amer. Desm. 1896, p. 233, t. 12, f. 25 ; Desm.

U. S. 1898, p. 321 ; Alg. Ceylon, 1902, p. 194 (forma) ; G. S. West, Brit,

Freshw. Alg. 1904, p. 177, f. 69 B ; Fritch, Alg. Ceylon, 1907, p. 245,

f. 4 F ; Bernard, Alg. unicell. domaine Malais, 1909, p. 19, t, 1, f. 12.
Didymoprium quadratum Racib. Nonn. Desm. Polon. 1885, p. 11.

Filaments nearly cylindrical, twisted ; cells about Ij
times broader than long, slightly constricted, with a
shallow linear sinus, semicells short, pyramidate-truncate,
lateral margins biundulate. basal angles acutely rounded ;
apex rather broad and truncate ; side view of semi-
cell quadrangular with scarcely any trace of a median
constriction. Vertical view subcircular with 2 opposite
mamillse. Chloroplasts axile, one in each semicell
with a central pyrenoid and 6 or 7 radiating plates.

Zygospore globose or subglobose, with a thick, smooth
membrane.

Length 19-20 \L ; breadth 25 \L ; breadth of apex
12'5pt ; thickness 19-20^ ; diam. zygosp. 24-28 [/..

SCOTLAND.- -Very rare : Slewdrum in Birse, Aberdeen
(Roy & Biss.).

Geogr. Distribution. — Galicia in Austria. Norway.
Sweden. Poland. Afghanistan. Ceylon. United
States. Guiana. Brazil.

This species is very similar in form to the preceding one,
except that it is relatively broader. The zy go spores of the two
species are, however, quite different.

Genus 26. GYMNOZYGA Ehren. 1841.

Ehrenb. in Berlin Monatsb, 1841, p. 212 (with description only of G. monili-
formis).

GYMXOZYGA. 255

Jacobs. Desm. Dane in. 1875, p. 213.

Hansg. Prodr. Alg. Bohm. 1888, p. 169.

De Toni. Syll. Alg. 1889, p. 797.

U'ille in Engler Xatur. Pflanzenfam. 1890, p. 15.

G. S. West, Brit. Freshw. Alg. 1904, p. 178.

Bambusina Kiitz. Phyc. germ. 1845, p. 140 ; Spec. Alg. 1849, p. 188.

De Bary, Conj. 1858, p. 76.

Rabenh. Flor. Eur. Alg. 1868, p. 152.

Delp. Desm. subalp. 1877, p. 54.

Kin-hn. A1-. Sc-hles. 1878, p. 132.

\Volle, Desm. I". S. 1S84, p. 24.

Cooke, Brit. Desm. 1887, p. 8

Comere, Desm. France, 1901, p. 197.

Cells cylindrical or barrel-shaped, united by their flat
ends to form slightly twisted filaments. There is a
very slight median constriction, and often a swelling
of variable size at the base of each semicell. Vertical
view circular, often with two opposite mamillse. Cell-
division similar to that of Desmidhini.

Zygospore smooth, oval or subglobose.

The genus Gymnozyga is very closely related to Desmidium,
and it has beeD -uggested by many previous authors that the
two genera should be united. However, the distinctive characters
of its form, the elongated barrel-shaped cells and the entire
absence of a distinct median incision, both characters which
contrast strongly with I)rs,,i'u1i '/////. seem to justify the retention
of Gymnozyga.

There is only one British species of the genus.

1. Gymnozyga moniliformis Ehrenb.
(PL CLXV, figs. 8, 9.)

Gynn>i>:i/'/n iitoHilifttrini* Khiviib. in Berlin Monatsb. 1841, p. 212 : Xordst.

Bornh! Drsm. 1888, p. 20!> ; De Toni. Syll. Alg. 1889, p. 797 ; West, Alg. W.

Jivlancl. 1S!»2. ]>. 117 : Alg. Kngl. Lake Distr. 1892, p. 7 : Turn. Freshw.

Alt:. K. India, 1893. p. 151 : JJoy \- Biss. Scott. Desm. 1893, p. 10 ; West

& G. S. West, A1-. S. England, 1897, p. 497 ; Alga-fl. Yorks. 1901, p. Ill ;

\\VI\v. Airie. Alg" 1897, p. 53 ; Alg. X. Ireland, 1902, p. 60 ; Alg. Burma,

1<M»7. p. 22(3; Fritt-h. Alg. Ceylon, 1907, p. 237, f . 3, K ; Bernard,

ALf. imicell. domaine Malais, 1909, p. 23, t. 1, f. 19 ; Borge, Sao Paulo

Siisswasseralg. 1918, p. 77.
Desiiiiiliinit Borreri Ralfs in Ann. Mag. Xat. Hist. 1843, ii, p. 375, t. 8, f. 4 ;

Mass. Brit. Freshw. Alg. 1845, p. 343, t. 83, f. 9, 10.
Bambusina Brebissonii Kiitz. Phyc. germ, 1845, p. 140; Spec. Alg. 1849,

p. 188 ; De Bary, Conj. 1858, p. 76, t, 4, f. 28, 29 ; Rabenh. Flor. Eur.

Ala. 1868, p. 153 ; Kirchn. Alg. Schles. 1878, p. 132 ; Wolle, Desm. U.S.

1884, p. 24, t. 1, f. 15-21 (?) : Cooke, Brit. Desm. 1887, p. 9, t. 4, f. 1 ;

Hauptfl. Zellm. Htillgallerte Desm. 1888, pp. 13, 56; t. 1, f. 19-21, 24,

25, 31-38.
Didymoprium Borreri Ralfs in Ami. Mag. Nat. Hist, xvi, 1845. p. 10, t. 3,..

256 BRITISH DESMIDIACE.E.

f. 5 ; Brit. Desm. 1848. p. 58, t. 3 ; Arch, in Pritch. Infus. 1861, p. 723,

t. 2, f. 38, 39.

Bambusina Borreri Delp. Spec. Desm. subalp. 1877, p. 54, t. 2. f. 1-7.
Gymnozyga Brebissonii Wille in Engler. Natur. Pflanzenfam. 1890, p. 15,
't. 9 J ; Hustedt, Desm. Bac. Tirol, 1911, p. 342.

Filaments twisting, formed of rather barrel-shaped
cells ; semicells with a small basal inflation, and an
extremely slight median constriction ; lateral margins
straight except for the broad rim at the base, apex
broad and truncate ; cell- wall often showing very

o «/

delicate longitudinal striations ; vertical view circular,
sometimes with two opposite mamillse. Chloroplasts
axile, one in each semicell, each having a central pyrenoid
and about 6 radiating plates.

Zygospores oval and smooth.

Length 25-30 u. ; breadth 17'5-22'o \L ; length of
zygospore 25-30 pi ; breadth 16-20 pi.

ENGLAND. — Cumberland ! Westmoreland, and in the
plankton of Codale and Easedale Tarns ! Lancashire
(Balfs). W., N., and E. Yorks ! Warwicks (Wills).
Surrey ! Sussex (Rolfs). Hants ! Devon ! (Harris).
Cornwall !

WALES. — General ! In the plankton !

SCOTLAND. — General ! zygospores from Aberdeen,
Kincardine, Perth and Argyle (Roy & Biss.). Lewis and

Harris, Outer Hebrides ! Hov, Orkneys ! Not un-

7 \j ' «/•

common in the plankton !

IRELAND. — General ! Zygospores from near Recess,
Galway ! Mayo ! Plankton of Galway and Kerry !

Geogr. Distribution. — France. Germany. Switzer-
land. Austria and Galicia. Bohemia. Hungary. Italy.
Spain. Norway. Sweden. Denmark. Finland. N.
Russia. Spitzbergen. Manchuria. India. Ceylon.
Burma. Singapore. Java. Australia. New Zealand.
E. Africa. Sandwich Isles. United States. Guiana.
Brazil. Colombia.

Var. gracilescens Nordst. (PL CLXV, fig. 10 ;

PL CLXVI, fig. 10.)

Bambusina Borreri var. gracilescens Nordst. in Wittr. & Nordst. Alg. Exs.
fasc. 7, 1880, no. 367, fasc. 21, 1889, p. 34.

GYMNOZYGA. 257

Bambusma Brebissonii var. gracilescens Wolle, Desm. U. S. 1884, p. 25.
Gymnozyga nioniUformis var. gracilescens De Toni, Syll. Alsr. 1889, p. 798 ;

W. & G. 8. West, Some N. Amer. Desm. 1896, p. 232, Cl2, f. 19 ; Alg.

Ceylon, 1902, p. 194 : Further Contrib. Plankt. Scott. Lochs, 1905,

p. 506 ; Borge, Sao Paulo Alg. 1918, p. 77, t. 5, f. 38.

Differs from the typical form only in the smaller
relative breadth of the cells.

Zygospores rectangular with rounded angles.

Length 24-30 IJL ; breadth 14-17[x ; length of zygo-
spore 28-37 IJL ; breadth 18-23[ji.

SCOTLAND.- -In the plankton !

Geoyr. Distribution. — Sweden. Ceylon. Java. United
States. Brazil.

VOL. V.

ADDENDA.

(Including recently described species and changes in

nomenclature.)

The late Dr. Liitkemiiller, during the twenty years pre-
ceding his death, made some careful investigations of cell-wall
structure in Desmids, and as a result of his work a number of
species must now be placed in a different generic position from
that originally assigned to them. Several genera are concerned in
these changes, and the majority of the alterations in nomenclature
set down below are due to the researches of Dr. Liitkemiiller.

Genus ROYA W. & G. S. W. (vol. i, p. 106).

This genus was placed by its discoverers amongst the Placo-
dermse near to Closterium. It was represented as resembling
the latter genus very closely, the chief distinction between the
two genera being the occurrence of apical vacuoles in Closterium
and their absence in Roya, and furthermore, Closterium has usually
two chloroplasts with the nucleus in a median position, whereas
Roy a has a single chloroplast with the nucleus in a lateral notch.
More recent research has shown that whilst these supposed
distinctions do not invariably hold, the two genera are never-
theless less closely related than was at first supposed.

The late Dr. Liitkemuller has pointed out (' Desm. Bohm.'
1910) that Roya has a very simple type of cell-wall structure and
cannot be allowed to remain amongst the Placoderm Desmids.
Its wall is destitute of pores and is a simple cellulose membrane,
and Dr. Liitkemuller has therefore suggested that it should be
placed among the Saccodermse near to Mesotcenium. The
position of Roya in vol. i, p. 106, next to Closterium is therefore
erroneous.

With the discovery of the new species, Roya anglica West
(vide infra), the original description of the genus must of necessity
be emended, since this species possesses several characters not
included in the de-jcription given in vol. i, p. 106, e. g. the presence

ADDENDA. 259

of apical vacuoles, and the concave ends of the chloroplast.
The new diagnosis is therefore as follows :

ROYA W. & (.1. S. W. emend. Hodgetts.* Cells un-
constricted, cylindrical or subcylindrical, straight or

«/ «/ Q^7

slightly curved, gently attenuated towards the apices,
which are more or less truncate or obtusely rounded ; cell
wall smooth, colourless, without pores ; chloroplasts
one in each cell, or, in old cells, divided at the middle,
axile, either rounded at the ends and extending to the
apices of the cell, leaving no colourless space, or with
concave extremities, in which case the cell has an apical
locellus at each end ; nucleus either lateral, lodged in a
tiny excavation of the chloroplast, or median, between the
two chloroplasts ; pyrenoids several, in a median series.

Roya anglica West.
(PL CLXVI, figs. 11-13.)

Roya aitylica West, Hodgetts in Journ. Botany, Iviii, 1920, p. 69.

Cells cylindrical or subcvlindrical, unconstricted, 5-

*/ «-'

15 (-20) times longer than broad, very slightly tapering
towards the apices, which are sub truncate, sometimes
straight, but usually slightly asymmetric, a slight
regular curvature being present ; greatest width of
cell not always in the middle, but more towards one

\j

end than the other ; in extreme cases almost clavate
in shape ; chloroplast axile with ? 4 longitudinal ridges,
usually one in each cell with a slight lateral concavity
for the nucleus, afterwards divided at the middle with
the nucleus between the two halves ; pyrenoids 4-6
in a longitudinal series ; chloroplasts concave at the
extremities, leaving room for an apical vacuole, without
moving granules ; cell-wall smooth, colourless, slightly
thickened at the apices.

Zygospore globose and smooth.

Length 35-80 (-112) p ; greatest width 7'5-9{Jt;
breadth of apices 5-7 JJL ; diam. zygosp. 20-26 p.

ENGLAND.- -Quinton, near Birmingham, Worcs !

* In 'Journ. Botany,' Iviii, p. 69, 1920.

260 BRITISH DESMIDIACEJE.

Roya obtusa (Breb.) W. & G. S. West,
(PI. CLXVII, fig. 6.)

The zy go spores of R. obtusa var. montana W. & G. S. West
(vol. i, p. 108) have been discovered by Harris in Devonshire,
and figured by him in ' Journ. Quek. Micr. Club,' 1917, t. 19r
f. 11. They are oval, about 20 /i long and 13 /t wide, and are
rather different in form from the zygospores of the typical form,
which, according to Kirchner, are spherical (cf. vol. i, p. 107).

Roya cambrica W. & G. S. W. (vol. i, p. 108).
Forma limnetica W. & G. S. W. (PL CLXVI, fig. 14).

Roya cambrica forma limnetica W. &• G. S. W. in Period. Plankt. Brit. Lakes,
1912, p. 430, t. 19, f. 11, 12.

A form with the apices of the cells very truncate.
Length 141-183 p ; breadth (in middle) 6(ji ; breadth
of apices 4 '4-5 [ju

SCOTLAND.- - Plankton of Loch Katrine, Perthshire.

Genus CYLINDROCYSTIS Breb.
Cylindrocystis Jenneri (Ralfs) West (vol. i, p. 77).

Penium Jenneri Ralfs in W. & G. S. W. Brit. Desm., vol. i. p. 77.
Cylindrocystis Jenneri (Ralfs) West, Liitkem. Gattung Penium, 1905,
p. 336.

The possibility of this species belonging to the genus Cylindro-
cystis was suggested in vol. i, p. 78, and that this suggestion was
a correct one has been confirmed bv Dr. Lutkemiiller.

*/

[CYLINDROCYSTIS OBESA W. & G. S. West (vol. i, p. 60) and C.
ROSEOLA Turn. (vol. i, p. 62) may according to Liitkem. (' Gattung
Cylindrocystis' 1913) remain provisionally in the genus Cylindro-
cystis, but they should be regarded as doubtful species of the
genus until they have been examined from the point of view of
cell-wall structure. C. DIPLOSPORA Lund., and C. MINUTISSIMA
Turn., are to be transferred to the genus Cosmariiim. Vide
infra, p. 266.]

ADDENDA. 261

Genus NETRIUM (Xag.).
Netrium oblongum (De Bary) Liitk. (vol. i, p. 66).

Var. aiigustatum West.

N. oblongum var. miyiixtntiiiH West, Clare Island Alg. 1912, p. 9.

Cells distinctly narrower than in the type.
Length 123 ^ ; breadth 23 p.
IRELAND. — Clare Island, Mayo !

Var. brevius West.

N. obl'iiiijinii var. In; vius \\V>t, Clare Island Alg. 1912, p. 9.

Cells about 3| times longer than broad.
Length 86 y. ; breadth 25 ;JL.
IRELAND.— Clare Island. Mayo !

v

Genus PENIUM Breb.

Following the investigations of Dr. LiitktMniiller the following
species must be removed from the genus Petnmn (see Liitk.
' Gattung Penium; 1905).

PENIUM JEXXERI Ralfs (vol. i. p. 77) must now be placed in
Cylindrocystis (vide supra, p. 260).

PENIUM LIBELLULA (Focke) Xordst. (vol. i. p. 73) and P.
NAVICULA Breb. must be transferred to the genus Clostermm
(n'de infra, pp. 261, 262).

PEXIUM ADELOCHOXDRUM Elfv. (vol. i, p. 93), P. MOOREAXUM
Arch. (vol. i, p. 80), P. CLEVEI Lund. (vol. i, p. 87), P. SUBTILE
W. & G. S. W. (vol. i, p. 92), P. LAGEXARIOIDES Roy (vol. i. p. 93),
P. CUCURBITIXUM Biss. (vol. i, p. 94). P. CURTUM Breb. (vol. i,
p. 97), P. IXCOXSPICUUM (vol. i. p. 101) and P. MIXUTUM (Ralfs)
Cleve (vol. i, p. 101) are all to be removed to the genus Cosmarium
Corcla (vide infra, pp. 266-268).

Genus CLOSTERIUM Nitzsch.
Closterium Libellula Focke (vol. i, p. 73).

clnsterium Libellula Focke, Phys. Stud. 1847, p. 58, t. 3, f. 29; Liitkem.

Gattung Penium 1905, p. 337.
Petrium Libellula (Focke) Xordst in W. & G. S. W. Brit, Desm. vol. i, p. 73.

262 BRITISH DESMIDIACEJE.

Closterium Navicula (Breb.) Liitkem. (vol. i, p. 75).

Penium Navicula Breb. in W. & G. S. W. Brit. Desm. vol. i, p. 75.
Closterium Xai-icula (Breb.) Liitkem. Gattung Peniu/n, 1905, p. 337.

Closterium angustatum Kiitz. (vol. i, p. 119).
Var. angustatum West.

CL angustatum var. angustatum West. Clare Isl. Alg. 1912, p. 10, t. 1, f. 5.

Variety with the striations all granular, granules
fairly distant, apices of the cell slightly recurved.
Length 457 ti ; breadth 22^.
IRELAND.- -Near Westport, Mayo !

Closterium Jenneri Kalfs (vol. i, p. 134).
Var. hibernicum West.

CL Jenneri, var. hibernicum West, Clare Isl. Alg. 1912, p. 12.

Cells longer and narrower than in the type, and less
strongly curved, about 120° of arc.

o */

Distance between apices 116 \L ; breadth 11 [i ; breadth
near apices 4*5 [Ji.

IRELAND.- -Near Westport, Mayo !

Closterium eboracense Turn. (vol. i. p. 140).
Var. achillense West.

CL eboracense var. achillense West, Clare Isl. Ate. 1912, p. 11, t. 1, f. 13,
t, 2, f. 16.

Cells always larger than in the type form, with the
ventral margin either slightly or distinctly tumid in
the median region.

Length 255-290 ^ ; breadth 57 '5-69 p.

IRELAND. --Near Dugort. and Slieve more, Achill Isle,
Co. Mayo !

Closterium Leibleinii Kiitz. (vol. i, p. 141).
Var. occidentale West.

CL Leibleinii var. occidentale West. Clare Isl. Alg. 1912, p. 12.

Cells not tumid in the middle, with the median part

ADDENDA. 263

of the inner margin nearly straight, or even slightly
concave, cells 138-175° of arc.

Length 137-172 JJL ; breadth 18*3-25 (j..

IRELAND.- — Near Dugort, Achill Isle ; near Louis-
hurgh ; Doo Lough and near Westport, Mayo !

Closterium tumidum Johns, (vol. i, p. 156).
Var. sphserospora West (PI. CLXVI, figs. 8. 9).

('I. fnniiiliiiii var. *jifi(rr<i*iK>r<i ('•. S. West in Journ. Bot. 1911, p. 84, f. 1.

A variety Avith short, thick cells.

V

Zygospore subglobose or ellipsoid-globose.
Length 48-66 [JL ; breadth 8-8'oa ; breadth of apex
3-4 IL : diam. zvo'osj). •J3<5-26u.

* • ' i.

KXCLAND. -Earlswood, Warwickshire !

This variety is distinguished from the typical form of Cl.
i tun i<l urn by its smaller and stouter cells, and the zygospore is
rounded, instead of rectangular with produced angles and retuse

margins.

Closterium Cornu Ehr. (vol. i, p. 157).
Yar. arcum West.

<'l. Cornu var. un-nni West, Clare Isl. Alg. 1912, p. 11.

Cells more strongly curved than in the type, up to
85° of arc, margins only parallel in the middle.
Length 138{/. ; breadth S'OJJL.
IRELAND.- -Lough Gall, Achill Isle. Mayo !

Closterium toxon West (vol. i, p. 160).
Var. validum West.

<'l. toxon var. valid H in West, Clare Isle Alg. 1912, p. 13, t. 1, f. G.

Cells twice as thick as in the typical form.
Length 250-260 u ; breadth 17'5-20jJt.
IRELAND. — Clare Isle, Mayo !

264 BRITISH DESMIDIACE.E.

Closterium pronum Breb. (vol. i, p. 173).
Forma brevius West.

Cl. promt ni i. brevius West, Clare Isl. Alg. 1912, p. 13.

Cells always distinctly shorter.
Length 222-250 \L ; breadth 8*4-9 u.
IRELAND. — Clare Isle, Mayo !

Genus EUASTRUM Ehrenb.

Euastrum laticolle West.
(PL CLXVI, fig. 3.)

Euastrum laticolle U. 8. West in Journ. Bot. 1912, p. 89.

Cells of medium size, about li times longer than

' o o

broad, very deeply constricted, sinus extremely narrow
and linear ; semicells 3-lobed, lobes separated by broad
and shallow concavities ; lateral lobes trapeziform with
the upper and lower angles gently rounded, sides di-
verging upwards and slightly concave ; polar lobe
transversely subrectangular, angles scarcely rounded
and slightly produced, apex convex, but retuse in the
middle ; with a small swelling in the middle of the semi-
cell near the isthmus. Vertical view transversely sub-
hexagonal-rectangular, with a subconical protuberance
in the middle of each side, ends concave, and with the
two angles at each end rounded, margins between the
central tumour and the polar angles broadly concave ;
polar lobe transversely subrectangular, angles subrotund
and sides slightly concave. Cell-wall irregularly and
somewhat distantly punctate.

Zygospore unknown.

Length 58 ^ : breadth 44 JJL ; breadth of polar lobe
26 \L ; breadth of isthmus 10 u ; thickness 30 si.

ENGLAND. — In a bog at Lindeth, near Bowness,
Westmoreland !

This is a very distinctive species, its only near relative being
E. Berlini Boldt (in ' Desm. Gronland,' 1888, p. 10, t. i, f. ]2). a

ADDENDA. 205

Desmid only known from Gronnedal in South Greenland. From
this, Arctic Desmid E. laticolle differs in the form of the front
view, having a closed and linear sinus, and lateral lobes of quite
a different shape. The general outline of the vertical view is
the same as in E. Berlini, but in the latter species the polar
lobe is described (and also figured) by Boldt as " broadly ellip-
tical" when seen in the end view, whereas that of E. laticolle is
rectangular with retuse sides and rounded angles.

Euastrum affine Ealfs (vol. ii, p. 17).
Forma scrobiculata Xordst.

il fijjine f. s<-r<il,i<-nlit<i Nnnl.-t. Xorges Desin. 1ST:>, p. 8 : Harris, in
Joum. Quek. Micr. Club, 11(17, p. LV><>.

The chief distinction of this form is the presence of a con-
spicuous ocellation in the middle of the semicell, which takes
the place of the two upper tumours.

ENGLAND.- -Devonshire

Euastrum montanum West (vol. ii, p. 58).
(PL CLXVII, fig. 5.)

The zygospore of Euastrum montanum has been figured by
Liitkemuller (<Zur K. d. Desm. Bohm.' 1910, p. 483). It is
spherical with numerous tubercles, each tubercle ending in a
simple hooked spine. Diam. zygosp. without spines, 29 /< ;
including spines

Euastrum insulare (Wittr.) Roy (vol. ii, p. 68).

Var. parvum West.

Eu. insulare var. par nun West, Clare Isl. Alg. 1912, p. 15.

Cells similar to the typical form, but smaller, and
relatively shorter, margins of lateral lobes less retuse.

Length 12-5-17 \L ; breadth 10-13 \L.

IRELAND.- -Xear Dugort, Achill Isle, and near Castle-
bar, Mayo !

266 BRITISH DESMIDIACE^E.

Genus MICRASTERIAS Ag.
Micrasterias papillifera Breb. (vol. ii. p. 91).
(PL CLXVII, fig. 11.)

Zygospore compressed, globose in front view, broadly
oval in lateral view, with numerous strong spines,
simple or slightly furcate at the apex. Diam. zygosp.,
without appendages, 85 km ; including appendages, 138^ ;
thickness, without appendages, 69 \L ; including appen-
dages, 115 y..

[The figure of the zygospore on PL XLIY, fig. 7, is not good,
and the dimensions for the zygospore given in vol. ii, p. 92,
are obviously erroneous. The compressed form of the spore ha&
not been previously noted, and the appendages are not identical
with those figured by Ralfs.]

Genus COSMARIUM Corda.
Cosmarium diplosporum (Lund.) Liitk. (vol. i, p. 61).

Cylindrocystis diplospora Lund. Desm. Suec. 1871, p. 83, t. 5, f. 7; W. &•

G. S. West, Brit. Desm. vol. i, p. 61.
Cosmarium diplosporum Liitkem. C4attung Cylindrocystis, 1913. p. 227.

Cosmarium pseudarctoides Strom (vol. i. p. 62).

Cylindrocystis minutisxinia Turn. Freshw. Alg. E. India, 1893, p. 16, t. 1,.

f. 24 ; W. &• G. S. West, Brit, Desm. vol. i, p. 62.
Cosmarium pseudarctoides Strom Alg. Tuddal, 1920, p. 31.

Strom has observed spores in the cell- wall of this tiny Desmid,
and for this reason transferred it to the genus Cosmarium.
Liitkemuller (' Gattung Cylindrocystis '). 1913, considered it to
be a doubtful species of Cylindrocystis.

Cosmarium Mooreanum (Arch.) Liitk. (vol. i, p. 80).

Penium Mooreamon Arch. Descr. New Cosm. etc. 1864, p. 24, t. 1, f. 34-44 ;.

W. &• G. S. W. Brit. Desm. vol. i, p. 80.

Dysphinctium Mooreanum Liitkem. Gattung Peniinn, 1905, p. 337.
Cosmarium Mooreanum Liitkem. Zur. K. Desm. Bohmens, 1910, p. 490.

ADDENDA. 267

Cosmarium Clevei (Lund.) Liitk. (vol. i, p. 87).

Penium Clevei Lund. Desm. Suec. 1871, p. 80, t, 5, f. 11 ; W. & G. S. W.

Brit. Desm. vol. i, p. 87.

Dysphinctium Clevei De Toni in Liitkem. Gattung Penium. 1905, p. 337.
Cosm't fin in f'lerei (Lund.) Liitk. Zur K. Desm. Bohmens, 1910, p. 486.

Cosmarium subtile (West) Liitk. (vol. i. p. 92).

Pen in m subfile W. & G. S. West. Brit. Desm. vol. i, p. 9J.
Dysphinctium -subtile Liitk. (iattunif Penium. 1905, p. 337.

subtile Liitkem. Zur K. Desm. Bohmens. 1910, p. 494.

Cosmarium adelochondrum (Elfv.) Liitk. (vol. i.

p. 93).

Penium adelo< hnmlium Elfv. Anteck. Kinska. Desm. ISS1, p. 17, t. 1, f. 13.
J)i/xpltiiicliiim (nlf-Jriffioinlrtitn Liitkem. Battling Penium. 19O5, p. 337.
Cosmarium mlilochondnun Liitkem. Zur K. Desm. Bohmens. 1910, p. 483.

Cosmarium lagenarioides* (Roy) Liitk. (vol. i. p. 93).

Penium ltii/<:ii<iri<>i<li* Kov in Bis^. Doin. Windermere, 1SS4. p. 197, t. 5

\V. cV <:'. S. \\. Brit. Desm. vol. i, p. 93.
])i/xj>lti tit-fin m ldf/i iiari»i<l> * Liitkem. Gattung Petiinm. 19(1.1. p. 337.

•

Cosmarium cucurbitinum (Biss.) Liitk. (vol. i. p. 94).

Penium rucurbilimim Biss. Desm. Windermere, 1884. p. 197. t. 5, f. 7;

W. ,V- G. S. \V. Brit. Desm. vol. i. p. 94.

Dysphinctium cwnrbitinnm Liitkem. Gattuni: I'tninm. 1905, p. 337.
Cosmnrinm cucurbitinum Liitkem. Zur K. Desm. Bohmens, 191<>, p. 487

Cosmarium curtum (Breb.) Ealfs (vol. i. p. 97).

curtum. Breb. 1838.
Cosmarium curtum (Breb.) Ralis. Brit. Desm. 1848, p. 109, t. 32, f. 9.
Penium ' /"ium Breb. in \Y. & <;. S. W. Brit. Desm. vol. i, p. 97.
Dysphixctiinn n/rfiim (Breb.) Xiig. Liitkem. Gattung Penium, 1905, p. 337.

Cosmarium bacillare Liitk. (vol. i, p. 101).

Penium inconspicuum West, Brit. Desm. vol. i, p. 101, t. 10, f. 15-17.
Dysphinctium inconspicuum Liitkem. Gattung Penium, 1905 p. 337.
Cosmarium bacillare Liitkem. Zur K. Desm. Bohmens, 1910, p. 484.

* The writer believes this to be the first time that this species has been
published under this name. In his paper, ' Zur K, Desm. Bohmens,' 1910,
however, Lutkeniiiller states that all the speeies listed by him under Dysphinc-
tium in ' Gattung Penium,' 1905, p. 337, should really be placed in Cosmarium.
It is therefore transferred with his authority.

268 BRITISH DESMIDIACE^.

Cosmarium docidioides Liitk. (vol. i, p. 101).

Docidium minutum Rail's, Brit. Desm. 1848, p. 158, t. 26, f. 5.
Penium minutuni W. & G. 8. West, Brit. Desm. vol. i, p. 101.
Dysphinctium minutum Liitkem. Gattung Penium, 1905, p. 337.
Cosmarium docidioides Liitkem. in litt. ; G. 8. West, Freshw. Alg. Columbia,
1914, p. 1037.

Cosmarium Ralfsii Breb. (vol. ii, p. 141).
Var. rotundatum West.

Cosmarium Ralfsii var. rotundatum West. Clare Island Alg. 1912, p. 19,
t. 2, f. 19.

A variety with very rounded lateral margins to the
semicells, basal angles sometimes very slightly pro-
duced, sinus nearly closed.

* */

Length 110^; breadth lOOjji ; breadth of isthmus

24 LL.

IRELAND.- -Near Westport, Mayo !

Cosmarium depressum (Nag.) Lund. (vol. ii, p. 176).

Var. minor West.

Cosmoriiini depressum var. minor West, Clare Island Algae, 1912, p. 19.

Cells smaller than in the type.
Length 26 \L ; breadth 20 pi.
IRELAND. — Clare Island. Mayo !

Cosmarium anceps Lund. (vol. iii, p. 47).
Var. tatricoides West.

Cosmarium anceps var. tatricoides West, Clare Island Alga?, 1912, p. 1(3.

Cells relatively broader than in the typical form,
isthmus compressed, but similar to that of C. tatricum
Racib. (that is, narrow, with conspicuously dilated
apex), cell- wall smooth.

Length 33 \L ; breadth 21 JJL.

IRELAND. — Clare Isle, Mayo !

" ./

ADDENDA. 269

Cosmarium Brebissonii Menegh (vol. iii. p. 161).

The zygospore of CoxtHfm'mn Brebissonii has been figured by
Harris in ' Journ. Quek. Micr. Club.' 1917. 1. 19, f. 10, from Devon-
shire. It is spherical, about 5<> n in diameter, and covered with
broad rounded tubercles, about 14 of which are to be seen round
the periphery.

Genus STAURASTRUM Meven.

i

Staurastrum Meriani Eeinsch (vol. iv, p. 122).
(PL CLXV1I, figs. 8, 9.)

Zygospore compressed, circular in front view, with
10-12 marginal crenations. Diam. 4.V.5 u ; thickness
27 p..

[This zygospore is almost identical with that of St. striolatum
(Niig.) Arch., see vol. iv. PL CXXVII, figs. 3-5.]

Staurastrum brevispinum Bivb. (vol. iv. p. 145).

(PL CLXYL fig. 2.)
Zygospore spherical, membrane smooth. Diam. 45 p.

[These zygospores were found by Mr. \V. J. Hodgetts, from
whose preparations the figure given was made.]

ADDITIONAL SYXOXYMS.

CLOSTERIUM CERATIUM Pertv (vol. i, p. 17(3), includes Cl. fasciculatum

Rabeiih. Alg. Ear. no. 2163, 1870.
EUASTRUM BENALE (Turp.) Ehr. f. GUTWIXSKII Schmidle (vol. ii, p. 53)

includes Eu. venustum Hantzscb, Rabenh. Alg. Eur. no. 1543, 1863.
COSMARIUM SPECIOSUM Lund. 1870 (vol. iii. p. 247) includes C.

Heuflerianum Grim, in Rabenh. Flor. Eur. Alg. 1868, p. 172; De Toni,.

Syll. Alg. 1889, p. 1053.

INDEX TO VOLS. I-V.

Roman numerals indicate the volumes ; page numbers in black
type refer to descriptions or diagnoses.

abbreviation, < Y>smarium, III 84

- t. minor, III 85

- var. planctonicum, III 85
abbreviata, Ursinella, 1 1 1 84

a l.« >ons»>. Kuastrum, II 23
• •n<i.s, Helierella, Jl 2:J
abnipta, Ursinella, III MI
abniptum, CKsterium, I 158
var. bivvin>. I 160

- var. cambricuin, I 1GO

- f. punctata, 1 159

- Cosmarium. 1 1 1 80
acanthophorum, Staui-astnnn, V 28
acarides, Staurastrum, I 14 ; \' 73

var. eboracciivjs, V 74
acerosa, Arthrodia, I 147

Baeillaria, I 140
;'<•<•!• i-uDi, Cln.sterium, I 146

- var. acerosum, I 148

- var. angolense, I 149

— var. angustum, I 148
var. elongatum, 1 148

— var. lanceolatum, I 149

- var. ma jus, I 147

- var. medium, I 148

- var. minus, I 148

— var. truncatuni, I 147

- var. typk-um, I 147
acerosus, Vibrio, I 146
aciculare, Closterium, I 174

var. subpronum, I 175
acicularis, Arthrodia, I 174
aciculiferum, Staurastrum, V 171, ISO
Actinocystis, II 77
aculeata, Binatella, IV 77

- Goniocystis(Trigonocystis), V 101
Heterocarpella, IV 79

aculeatum, Desmidium, V 160

Didymidiurn (Staurastrum), V

1(51
Didymidium (Xanthidium), IV

79~
— Holocanthum, IV 79

aculeatum, Phycastrum, V 161

- (Stenactinium), V 161

- Staurastrum, V 1.15), 160, 162,

163

- var. bifidum, V 187

- var. rontrovrrsuin, V 162

- subsp. cosmospinosum, V 164
var. Ehrenbergii, V 161

var. ornatum f. simplex, V
Us
Xanthidium, IV 78

var. basidentatum, IV 80

- Zygoxanthium, I \" T'.i
acuminata, Arthrodia, I 130
acuminatum, Cl^-tt-rium, I 130
Acus, Closterium. I 188
acuta, Arthrodia, 1 177

K'-hinella, I 177
Frustulia, 1 177

- Sjiirotienia, I 46

- Stauroceras, I 177
acutum, Closterium, I 177

— var. 3, I 179

- var. Linea, I 178

- Staurastrum, IV 109
adelochondrum, Cosmarium, V 267

Dysphinctium, V 267
Penium, 193; V 281, 267

adoxum, Cosmarium, III 78

affine, Euastrum, II 17

- f. scrobiculata, II 18 ; V 265

- Staurastrum, V 128
affinis, Helierella, II 17
alatum, Cosmarium, III 256

- var. ajquatoriense, III 257
alpestre. Cosmarium, III 24
alpina, Ursinella, II 149
alpinum, Cosmarium, II 149

— var. Garrolense, III 12

var. Helveticum, III 12

— Xanthidium, IV 116

alternans, Staurastrum, IV 170
var. coronatum, IV 172, 184

272

INDEX.

alternans, Staurastrum, var. diver-
gens, IV 178

- var. pulchrum, IV 172
Americana, Helierella, II 118

- Micrasterias, II 117

var. Boldtii, II 120

- f. genuina, II 118

— var. Lewisiana, II 120

- f. Mahabuleshwarensis, II 121
var. recta, II 119

- var. typica, 1 1 118

- f. Wallichii, II 122
Americanum, Enastrum, II 117
amcBiia, Ursinella, IV 29
amcenum, Euastrum, II 56

- Cosmarium, IV 29

- var. annuiatum, IV 30

- var. Lundellii, IV 30

- var. mediolseve, IV 31

- Staurastrum, IV 124

- subsp. acanthophorum, IV
126

- var. italicum, IV 126

- f. spetsbergensis, IV 126

- var. tumidiusculum, IV 126
amphidoxon, Staurastrum, V 181
ampullacea, Helierella, II 19

- Micrasterias, II 122
ampullaceum, Euastrum, II 19

- f. scrobiculata, II 19, 20
anatinum, Staurastrum, I 13 ; V 142,

160
var. biradiatum, V 145

- var. grande, V 144

— var. Lagerheimii, V 144

- var. longibrachiatum, V 144,
146

- var. pelagicum, V 146

- var. truncation, V 145
anceps, Cosmarium, III 47

- f. crispula, III 49

— f. glabra, III 47

- var. tatricoides, V 268
Dysphinctium, III 47

- f. crispula, III 49
Ancyclonema, I 25, 26
anglica, Roya, V 259
anglicanum, Euastrum, II 44
angulatum, Staurastrum, IV 154

- var. planctcmicuin, IV 154
angulosa, Helierella, II 107

Micrasterias, II 107
angulosum, Cosmarium, III 93

- var. coiicinnum, III 94

— Didymidium (Micrasterias), II
107

- Staurastrum, V 131
angusta, Arthrodia, I 148

angustata, Arthrodia, I 119
angustatum, Closterium, I 119, 148

- var. angustatum, V 262

- f. Eichleri, I 119
var. speciosum, I 119

- var. subrecta, I 119

- Cosmarium, II 190
anisochondra, Ursinella. Ill 212
anisochondrum, Cosmarium, III 212
annuiatum, Cosmarium, IV 39

- var. elegans, IV 40
Dysphinctium (Calocylindrus), IV

39

Penium, IV 39

annulatus, Calocylindrus, IV 39
anomalum, Cosmarium, IV 14, 15, 26
ansatum, Didymidium (Euastrum),
II 27

- Helierella, II 27
Euastrum, II 27

- var. pyxidatum, II 29

- var. sublobatum, II 27, 29
antiacerosum, Closterium, I 117
antilopa3a, Heterocarpella, IV 63
antilopseum. Cosmarium, IV 63

- Xanthidium, I 14 ; IV 63

- var. depauperatum, IV 70

- var. fasciculoides, IV 64

- f. triquetra, IV 66

- var. hebridarum, IV 69

- var. hirsutum, IV 64

- var. incertum, IV 66
var. laeve, IV 68

- var. oligacanthum, IV 68

- var. ornatum, IV 64

- var. polymazum, IV 67

- var. Schmidlei, IV 64

- var. triquetrum, IV 66
apiculata, Helierella, II 98

— Micrasterias, 14; II 97

- var. fimbriata, II 99

- f. brachyptera, II 101
— f. spinosa, II 100

apiculatum, Didymidium (Micras-
terias), II 98

— Euastrum, II 97

- Staurastrum, V 6
apiculiferum, Xanthidium, IV 85
apiculosum, Phycastrum, V 65
Aplanospores, 19, 23 ; V 229, 232, 239
Aplodesmus, IV 89

Aptogonum, V 240

Desmidium, V 242

- var. /3, V 243

- var. acutius, V 244

— var. Ehrenbergii, V 243
Arachne. Goniocystis (Pentasterias)
V 151

INDEX,

273

Arachno, Phycastrum, V 151

• (Stenactinium), V 151

- Staurastrum, V 151

• var. arachnoides, V 152

• var. curvatum, V 152

• var. tetracerurn, V 119
arachnoides, Staurastrum, V 152
Archeri, Sphaerozosma, V 2(.)S
Archeriana, Arthrodia, I 115
An-herianum, Closterium, I 115

var. Cynthia, I 113
var. typicum, I 115
Aivherii, Docidium, I 213
Pleurotsenium, 1213

- Staurastrum, V 155
Arctiscon, Staurastrum, 114: V 193

- Xanthidiuni, \' l!i:{
aivtoa, I 'rsinella, 11141
an-toum, Cosmarium, 1 1 [ 41

• f. minor, III 42

• var. tatricum, III 42

• var. typicum, UI 41
areuutum, Clostcrium, I 131

- Stanrastrum, V 180

• var. Guitanense, V 180
var. subavicula, V l.Sl
var. vastum, V 181

aristiferum, Staurastrum, V 18, 22

• var. protuberans, V 23
armatum. Cosmarium, IV 51

Didymidium (Xanthidium) IV 52
Euastrum, IV 51

- Schizacanthum, IV 52

— Xanthidium, IV 51

• var. Americanum, IV 52

• var. cervicorne, IV 55

• var. fissum, IV 54

• var. irregularius, IV 55

— var. supernumerarium, IV 52

— var. \Volleanum, IV 52
armigernm, Staurastrnm, V 191
armillare, Mixotsenium, V 235
armillatum, Cosmarium, III 167

- Spondylosium, V 228
Armstrongianum, Euastrum, II 30
Arnellii, Cosmarium, III 205

• f. compressa, III 205

- Staurastrum, V 79

— var. inornatum, V 80

• var. spiniferum, V 80

- Ursinella, III 205
Arthrodesmus, I 27 ; IV 88
Arthrodia, 1110
articulatum, Xanthidium, V 188
Asexual reproduction, I 9
asperum, Cosmarium, III, 261

— Didymidium (Stanrastrum), V 74
— Docidium, I 30, 31

VOL. V.

asperum, Gonatozygon, I 30, 31

— Leptocystinema, I 30

- Staurastrum, V 74

• var. proboscidium, V 129
asphaerospora, Ursinella, II 163
asphserosporum, Cosmarium, II 163

• var. strigosum, II 164
attenuata, Arthrodia, I 169
attenuatum, Closterium, I 169

- Cosmarium, III 118
Dyspbinctium, III 118

attenuatus, Calocylindrus, III 118
Auhertianum, Spbaerozosma, V 207

• var. Archeri, V 208, 211
aversum, Staurastrum, IV 144
Aviciila. Staurastrum, V 39, 40, 125,

172

— var. aciculiferum, V 171

• var. subarcuatum, V 41, 43
\ ar. vcrrucosum, V 41

bacillare, Cosmarium, I 97 ; V 267
Didymidium (Staurastrum), V 84
Phyrastrum, V S \-

- Staurastrum, \ 84

• var. obesum, V 84

• var. undulatum, V 85
bai-illaris, Binatella, \' 84
Baculum, Closterium, I I'.KJ

Docidium, 1 193

Penium, I 193

Pleurotaanium, I 194
Baillyanum, Closterium, I 117
Balmacarense, Closterium, I 161

— f. minor, I 161
Bambusina, V 225

bambusinoides, Sphasrozosma, V 226
harbaricum, Staurastrum, V 157
basilicum, Cosmarium, IV 44
Beckii, Cosmarium, III 238
Bennettii, Helierella, II 124
Berginii, Penium, I 75

Berlini, Euastrum, V 264
bibrachiatum, Dichotomum, var.
cymatium, V 121

— Staurastrum,var. cymatium, V 121
Bicardia, Cosmarium, III 98

— Ursinella, III 98

bicorne, Staurastrum, V 116, 117
bicornutum, Xanthidium, IV 63
bicrenatum, Cosmarium, IV 38
bicuneatum, Cosmarium, var. tatri-
cum, III 42

bidens, Desmidiuni, V 32
bidentatum, Euastrum, II 39

— Staurastrum, V 34
Bienneanum, Staurastrum, IV, 135

var. ellipticum, IV 137

18

274

INDEX.

Bienneanum, Staurastrum, f. grcen-
landica, IV 183

- f. spetsbergensis, IV 137
bifida, Goniocystis (Trigonocystis), V

88
bifidum, Euastrum, II 80

Phycastrum, V 32
(Stenactinium), V 33

— Staurastrum, V 32, 88
bifidus, Arthrodesmus, IV 113

- var. latidivergens, IV 115
bigorrense, Cosmarium, III 18
Bigorrianum, Euastrum, IV 52

Xanthidium, IV 52

— Zygoxanthium, IV 52
binale, Cosmarium, II 51

Didymidium (Euastrum), II 51

- Euastrum, I 14 ; II 43, 51

- var. (3, II 56

- var. angustatum, II 190

• var. elobatum, II 54

var. elongatum, II 72

- f. Gutwinskii, II 53 ; V 269
var. hians, II 53

- var. insulare, II 68

f. minor, II 52

f. minuta, II 51

- var. retusum, II 54
var. rotundata, II 43

- f. secta, II 53

- var. subelobatum, II 55

- var. typicum, II 51
f. ventricosa, II 51

binalis, Helierella, II 51
binerve, Cosmarium, III 123

- Dysphinctium, III 123
binodula, Ursinella, III 174
binodulum, Cosmarium, III 174
binum, Cosmarium, III 246

Ursinella, III 246
bioculata, Heterocarpella, II 165

- Ursinella, II 165
bioculatum, Cosmarium, I 14 ; II

165; III 90

- var. crenulatum, II 150

- f. depressa, II 166

- var. hians, II 165
Didymidium (Cosmarium), II 165
Euastrum (Cosmarium), II 165

bipapillatum, Cosmarium, III 214
bipunctatum, Cosmarium, III 213

- f. subrectangularis, III 214
bireme, Cosmarium, III 77
biremis. Ursinella, III 77

bireta, Ursinella, IV 26
biretum, Cosmarium, IV 25

- f. grconlandica, IV 26

•! — — var. intermedium, IV 26

biretum, Cosmarium, f. subconspersa,
IV 26

var. trigibberum, IV 28

bisenarium, Xanthidium, IV 73
bispiralis, Spirotsenia, I 45
Blyttii, Cosmarium, III 225

• var. Novse-Sylvse, III 227
var. tristriatum, III 228

Ursinella, III 225
Boeckii, Cosmarium, III 234

• sub sp. bipapillatum, III 214
Ursinella, III 234

Boldtianum, Cosmarium, III 229 ; IV

37

boreale, Staurastrum, V 112
Borgeaiium, Staurastrum, V 129, 130
Borreri, Bambusina, V 256

• var. gracilescens, V 256
Desmidium, V 255

- Didymoprium, V 255
botrophillum, Staurastrum, IV 166
Botrytis, Cosmarium, IV 1

• var. afghanicum, IV 4

• var. Brebissonii, III 161

• var. depressum, IV 7

• var. emarginato-constrictum,

III 189

• var. emarginatum, IV 6
— var. gemmiferum, IV 5

• var. interstitiale, IV 2

• var. mediola3ve, IV 6

• f. obliqua, IV 3

• var. ochthodes, IV 10

• var. paxillosporum, IV 4

• var. pseudospeciosa, IV 2

• var. squamosum, IV 10

• var. subtumidum, IV 4

• var. tumidum, IV 5
Botrytis, Didymidium (Cosmarium),

IV 2

Euastrum (Cosmarium), IV 2

— Heterocarpella, IV 1

- Ursinella, IV 2
brachiatum, Staurastrum, V 88, 92

Phycastrum, V 89

brachioprominens, Staurastrum, V 150
brachyacanthum, Staurastrum, IV

191

brachycerum, Staurastrum, V 109, 136
brachyptera, Helierella, II 101

- Micrasterias, II 101

• f. bispinata, II 101
Brasiliense, Staurastrum, V 35

• var. Lundellianum, V 36

• var. Lundellii, IV 120 ; V 35
Braunii, Didymidium (Cosmarium),

III 9, 91

— Mesotsenium, I 51

INDEX.

275

Brnunii, Mesotaenium, var. Greyi, I
49

— var. minus, I 52
Brebissonii, Bambusina, V 255

— var. gracilescens, V 257

— Closterium, I 216

- Cosmarium, III 161 : V 269

- f. erosa, III 161

• var. genuina, III 203
var. horrida, III 161

- f. subtumida, III 161

- Cylindrocystis, I 14, 58

— var. Jenneri, I 77

• var. minor, I 59
Didymidium (Cosmarium), III

161
Brebissonii, Gonatozygon, I 31

— var. Kjellmanni, I 33
var. Iseve, I 32

— var. minutum, I 33

- ( iymnozyga, V 25(5
Holocanthum, TV 77

— Palmogloea, I 5S
Penium, I 58

var. Jenneri, I 77

(Tetmemorus), 1217

- Staurastrum, V 61

• var. brevispinum, V 63
• var. ordinal um, Y 71

Tetmemorus, I 14, 216
— - var. attenuatus, I 218

— var. minimum, 1 219

— var. minor, T 218, 219

— var. turgidus, I 218

- Ursinella, III 161

- Xanthidium, IV 77

var. basidentatum, IV 80

- var. varians, IV 78
Brefeldii, Pleurotsenium, I 204
brevispina, Binatella, IV 145
brevispinum, Staurastrum, IV 145 :

V 5, 269

• var. altum, IV 148

- var. Boldtii, IV 147
var. Dickiei, V 3

— f. hexagona, V 145

— var. inerme, IV 141, 149
f. major, IV 147

— f. minima, IV 147

— f. minor, IV 145

— var. minor, IV 145
var. obversum, IV 148

Broomei, Cosmarium, IV 22, 24

— Ursinella, IV 24
Bryophila, Endospira, I 39

— Spirotsenia, I 39
bullosum, Staurastrum, V 55
Bulnheimii, Arthrodesmus, IV 105

Bulnheimii, Arthrodesmus, var. sub-
incus, IV 105
Burmense, Staurastrum, V 113

cselata, Ursinella, III 135
caelatum, Cosmarium, III 134

— var. hexagonum, III 137
— • var. spectabile, III 136

calcarea, Ursinella, III 235
calcareum, Cosmarium, III 235
caldariorum, Mesotaenium, I 53
Calueylindrus, I 24 ; II 126
calospora, Arthrodia, I 138
ealosporum, Closterium, I 138

- var. galiciense, I 140

- f. major, I 139
cambiense, Euastrum, II 45
i-ambrica, Roya, I 108

- f. limnetica, V 260
Ursinella, III 9

Cambricum, Cosmarium, III 9

- f. minor, III 10

— var. typica, III 9
campanulatum, Staurastrum, IV 177
canaliculatum, Cosmarium, II 198
i-andianum, Arthrodia, I 169

Closterium, I 169, 170
('apitula, Ursinella, III 119
Capitulum, Cosmarium, III 119

— var. groenlandicum, III 120

- Staurastrum, IV 124

- var. acanthophorum, IV 126

— var. amcenum, IV 124

— var. italicum, IV 126

— var. spetsbergense, IV 126
var. tumidiusculum, IV 126

caudatum, Closterium, I 188
celatum, Euastrum (Cosmarium), III

221

Cell-wall, structure of, I 14
Centrenterium, IV 50, 89
Cerastes, Staurastrum, I 14 ; V 141
Ceratium, Arthrodia, I 176

- Closterium, I 176 ; V 269
Chavesii, Staurastrum, V 134
chlamydosporum, Mesotsenium, I 52

- var. Archeri, I 53

- f. minor, I 53

- Palmogloea, I 53
Chloroplasts, I 6, 93

circulare, Cosmarium, II 27, 136, 137

f. minor, II 137

Didymidium (Cosmarium), II 136
Euastrum, II 27

— var. jS, II 20
var. 7, II 22

— var. Falesiensis, II 20
var. Hassallii, II 27

276

INDEX.

circulare, Euastrum, var. Ralfsii,
II 22

- var. sinuosum, II 20
circularis, Helierella, II 27

- Ursinella, II 136
clavatum, Docidium, I 211

Pleurotsenium, I 211
claviferum, Staurastrum, V 72
clepsydra, Cosmarium, III 98

- Staurastrum, IV 152

— var. sibiricum, IV, 119, 152

- f. trigona, IV 153
Clevei, Cosmarium, V 267

Dysphinctium, I 87 ; V 267
Penium, I 87 ; V 261, 267

- var. crassum, I 88

- Staurastrum, V 92, 177
closteridia, Endospira, I 39

Palmoglcea, I 39

- Spirotaenia, I 39
Closteriea?, I 26, 106
closterioides, Penium, I 73

- f. interrupts, I 74

- var. Navicula, 1 75
Closterium, I 1, 3, 109
coarctatum, Cosmarium, III 69

Desmidium, V 252

- var. cambricum, V 252

- var. gracileps, V 253
Desmidium (Didymoprium) V

252

- Staurastrum, IV 139

- var. subcurtum, IV 139
Collecting of Desmids, I 15
coloratum, Closterium, I 152
commisurale, Cosmarium, III 154

- var. acutum, III 155

- var. crassum, III 155
Didymidium (Cosmarium), III

154

Euastrum, III 154

commissuralis, Heterocarpella, III
154

- Ursine! la, III 154
compressum, Desmidium, V 209. 250
concinnum, Cosmarium, III 94

- var. laeve, III 95
Didymidium (Cosmarium), III 95
Euastrum, III 94

- Xanthidium, IV 86

- var. Boldtiana, IV 87
condensata, Spirotaenia, I 38 *
conferta, Helierella, II 88

- Micrasterias, II 88

- var. hamata, II 90
confusa, Ursinella, III 203
confusum, Cosmarium, III 203

- subsp. ambiguum, III 199

var. regu-

confusum, Cosmarium,

larius, III 199, 203
connatum, Cosmarium, III 25

— var. pseudoconnatum, III 27

- var. truncatum, III 26

— Dysphinctium, III 25

- Staurastrum, V 15
connatus, Calocylindrus, III 25

- var. minor, III 28

- var. typicum, III 25
conspersa, Ursinella, IV 14
coiispersum, Cosmarium, IV 13

- var. latum, IV 15

- var. Quadrum, IV 20

- var. Ralfsii, IV 14

- var. rotundatum, IV 16

- var. subrotundatum, IV 17
conspicuum, Staurastrum, IV 143
constrictum, Cosmocladium, V 198,

200

Dictyosphserium, V 198
contortum, Staurastrum, var. pseudo-

tetracej'um, V 122
contracta, Ursinella, II 170

- Cosmarium, II 170

- var. Cracoviense, II 174

- var. ellipsoideum, II 172

- var. Gartanense, II 173

- f. Jacobsenii, II 171

- var. silesiacunij II 170
controversum, Cosmarium, IV 9

- Staurastrum, V 160, 162

- Xanthidium, IV 59

- var. planctonicum, IV 60
controversus, Arthrodesmus, IV 103
convergens, Arthrodesmus, IV 106

- f. curta, IV 107

- var. incrassatus, IV 109

- f. minor, IV 107

- var. subulatus, IV 109

- f. typica, IV 107

— Cosmarium, IV 107
Didymidium, V 3

- (Staurastrum) var. ellipticum,
IV 107

B. trigonum, V 3
Euastrum, IV 107
Euastrum (Tetracanthium) IV
107

— Scenodesmus, IV 107

- Staurastrum, IV 107

- var. armigera, IV 107

- var. inermis. II 176

- Xanthidium, IV 107
Corbula, Cosmarium, III 183

- Ursinella, III 183
Cordanum, Closterium, I 145

— Cosmarium. Ill 113

INDEX.

277

Cordanum, Dysphinctium, III 113
Cordanus, Calocylindrus, III 113
cordatum, Staurastrum, IV 156
corniculatum, Staurastrum, IV 163

• var. spinigerum, IV 164

— var. variabile. IV 164
Cornu, Arthrodia, I 157

- Clost<-rium, 1 156, 157

• var. arcum, V 263

• var. /3, I 15ii

• var. siamense, I 157
f. tumida, I 156

- Stauroceros, I 157
cornubiense, Euastrum, II -2, 70

- Staurastrum, V 174
cornuta, Micrasteria.s, H 124
cornutum, Staurastnnn, \' 31
coronata, Ursinella, I V I:;
conmatum, ( 'osmarium, 1\' 13

Docidium, I lit'.)
var. nodulosum, I 201

— var. iindulatum, I 2o2

- Pleurotaenium, I 199

• var. fluctuatum, 1 200

• var. nodulosum, 1 200

- f. labiata, I 2O2

• var. robustum, I 200
Corribense, Cosmarium, ill 120
Corriense, Cosmarium, III 133
run-upturn. < 'osmarium, 11 130
Cosmarica?, I 26, 1!)!'
cosmarifonne, Xanthidium, IV 4!)
cosmarioides, PleurotaBnium, III 01

( 'o-irnarioides, .Staurastrum, IV ll'.t,

161

Cosmarium, [ 2, :}. II, 24, 27 ; 11 125
Cosmocladium, V 197
• " -mospinosum, Staurastrum, V 72,

164
costata. Arthrodia, 1 121

- Ursinella, 111 2:}!)
costatum, Closterium, I 120

- Cosmarium, 111 2o(.t
rrassa, Cylindrocystis, 1 14, 59

- Helirrclla, II 5
Heterocarpella, IL 5
Penium, [ 5!)

crassangulatum, Euastrum. 11 70

• var. ornatum, II 70
crassicolle, Euastrum, II 71

• var. typicum, II 71

' T .issjrollis, Helierella, II 71
crassiusculum, Penium, I 96
crasso-humerosum, Euastrum, II 5
crassum, Closterium, I 184

- Cosmarium, H 5
Euastrum, II 5

var. fi, II 4

crassum, Euastrum, var. appendicu-
latum, II 5

var. cornubiense, II 8

var. ma jus, II 5

— — var. scrobiculatuui, II 7

— var. Taturnii, II 8
crassus, Arthrodesmus, IV 102
crenata, Micrasterias, II 85

— Ursinella, IV 35

crenatum, Cosmarium, I 14 ; IV 35

— var. alpinum, II 149

- var. bicrenatum, IV 38

- f. Boldtiana, IV 37

- subsp. costatum, III 239

- var. major, IV 35

- var. psychophilum, IV 35
var. Ralfsiana, IV 35

— var. subcrenatum, III 144

- f. sublaevis, IV 35

— f. tricrenata, IV 35
Euastrum, III 144 ; IV 35

- (Cosmarium), III 14
crenulata, Helierella, III 40
'•ivnulatum, Cosmarium, II 150

- var. Reinschii, III 86
Euastrum, II 150 ; III 40

— (Cosmarium), II 150

• Phycastrum (Stenactinium), V

110

Staurastrum, V 110
crispulum, Euastrum, II 2, 72
cristata, Ursineila, III 139
cristatum, Cosmarium, III 139

— Didvmidium (Xanthidium), IV

71

llolocanthum, IV 71
Phycastrum (Pachyactinium), V

47

— Staurastrum, V 47, 411
Xanthidium, IV 70

- f. angulata, IV 72
var. Delpontii, IV 74

- var. irla bruin, IV 72

— var. leiodermuni, IV 72

- var. reniforme, IV 70

- var. spinuliferuni, IV 73

- var. uncinatum, IV 73
cruciatuui, Cosmarium, IV 47

- Staurastrum, V 165
cruciferum, Cosmarium, I 100

Dysphinctium, I 100
Penium, I 100

Crux-melitensis, Cosmarium, II 116
Euastrum, II 116

— Helierella, II 116

— Micrasterias, II 116
var. furcata, II 113

— — f. punctulata, II 117

278

INDEX.

Crux-melitensis, Micrasterias, var.

superflua, II 116
Crystals, I 5
Cucumis, Closterium, I 140

— Cosmaridium, II 153

— Cosmarium, II 152

— var. anglica, II 153

- var. helveticum, II 154

- var. magnum, II 154
var. typica, II 153

Didymidium (Cosmarium), II 153

— Euastrum (Cosmarium), II 153

— Pleurotseniopsis, II 153
Cucurbita, Calocylindrus, III 106

— Cosmarium, I 14 ; III 106

var. attenuatum, III 108

f. latior, III 108

- f. major, III 107
Dysphinctium, III 106

cucurbitinum, Cosmarium, V 267

- Dysphinctium, V 267

— Penium, I 94 ; V 261, 267

var. major, I 95

- var. minor, I 95

- var. poly morph urn, 1 95

- var. Scoticum, I 96
cumbricum, Staurastrum, V 55

- var. cambricum, V 56
cuneata, Helierella, II 26
cuneatum, Euastrum, II 25

- f. punctata, J.I 26
curtum, Closterium, I 97 ; V 267

- Cosmarium, I 97 ; V 267
Dysphinctium, 1 97 ; V 267
Penium, I 8, 97 ; V 267

- f. intermedia, I 98

- f. major, I 98

- f. minor, I 98

- f. minuta, I 98

- var. obtusum, I 99
curtus, Calocylindrus, 1 97
curvatum, Staurastrum, V 19, 21
cuspidata, Binatella, V 23
cuspidatum, Phycastrum, V 23

- Staurastrum, V 23

- var. coronulatum, V 26

- var. dejectum, V 7

- var. divergens, V 25

- var. longispinum, V 25
var. maximum, V 24

cuticulare, Penium, I 85
cyclica, Ursinella, II 145
cyclicum, Cosmarium, I 14 ; 11 145
var. aiigulatum, II 146

- var. arcticum, II 146

- var. maculatum, II 14l>

- var. Nordstedlianum, [I 146

- var. truiicatum, II 147

cylindricum, Arthrodesnius, V 250

- Cosmarium, IV 43

- Desmidium, I 10 ; V 249

- (Didymoprium), V 250
Didymoprium, V 250
Hyalotheca, V 250
cylindricus, Calocylindrus, IV 43

- var. hexagona, IV 122
Cylindrocystis, I 2, 3, 24, 26, 57 ; V 260
Cylindrus, Calocylindrus, var. geiiu-

inus, I 84

- var. silesiacus, I 84

- Closterium, I 84

- Cylindrocystis, I 84
— Dysphinctium, I 84

Penium, I 24, 84

- var. subtruncatum, I 85
cymatonotophorum, Cosmarium, III

40

cymatopleura, Ursinella, III 5
cymatopleurum, Cosmarium, I 14 ; 111

5

- var. Archerii, III 6
f. polonica, III 5

— var. Tyrolicum, III 6
Cynthia, Arthrodia, I 113

- Closterium, I 113

- var. curvatissimum, I 114
cyrtocerum, Phycastrum, V 135

- Staurastrum, V 134, 135

— var. compactum, V 136

Daaei, Staurastrum, V 25
danicum, Cosmarium, III 224
Davidsonii, Cosmarium, III 20
Debaryi, Calocylindrus, III 62
— Cosmaridium, III 62

- Cosmarium, III 61

- var. turgidum, III 115

- var. typicum, III 62
Dysphinctium, III 106
Pleurotseniopsis, III 62

decedens, Cosmarium, III 43

- var. boreale, III 43

- var. carpaticum, III 43

- var. sinuosum, III 44
Euastrum, III 43

declive, Euastrum, II 48
decora, Arthrodia, I 185

Ursinella, III 135
decorum, Closterium, I 184

- Cosmarium, III 135

- (Euastrum) Cosmarium, III 135
De Ureyi, Mesotsenium, I 48, 49

- var. breve, I 50

- f. major, I 49

- f. tennis, I 50
dejecta, Binatella, V 7

INDEX.

279

dejectum, Staurastruin, V 7, 11, 12,

14
var. a, V (j

— var. [3, V 1 1

— var. apiculatum, V 0

— var. connatum, V 15

— var. Debaryanum, \ '2

- var. Dickiei, V .'!
var. inttatum, V 10

- var. lunatum, A' 7

- f. major, V 9

— var. mucronatum, V 11
var. patens, V 9

- f. punctata, V 7

- subsp. Tellaniii. IV W
Delpontei, Arthrodia, 1 185

- ' 'losterium, I 185
deltoideum, Staurastrum, \" r>7
denticulata, Helierella, II lo.l

Micrastcrias, J Id. 14 ; 11 105
var. aiiirulosa, II 107

- var. angusto-sinuata. II 108

— var. intermedia, 11 lo'.i

- var. licmoides, 1 1 lit1.)

- var. notata, II 108

- var. subnotata, II 108

- var. Thomasiana, II 1 1(»
denticulatum, Didymidium (Micras-

tcrias), II lo.'i
Euastrum, II 56

- var. granulatum, II 57

- Ph vast rum (Pachyactinium), V

38

Maurastnim, \' 38, 41
dentiferum, Cosmarium, 111 156
Denotarisii, Cosmarimn, III 124
ilrpn-ssa. I'rsinella, II ITti
depressum, Cosmarium, II 176

- var. achondrum, II 177

- var. minor, A' 268

- var. renifnrinc. 1 1 178
Euastrum (Tetracanthium), il

170

- Spli;cn>/,i>sma. \' 223

- Spomlylosium, V 223, 224

- Staurastruin, IV 135

— f. aperta, IV 134
desmidioides, Debarya, I 12, 24
Dcsiiiidium, 1 2, V 240

- Aptogonum, V 242

- Odontella. V 243

De Tonyi, Staurastruin, V 174
diagoiium, Aptogonum, V 243
Diana?, Arthrodia, I 130

- Closterium, I 130

— var. arcuatum, 1 131

- var. incurvum, I 130
var. Jenneri, I 135

Dianse, Closterium, var. tvpicum, I
130

- var. Venus, I 137
dichotoma, Alicrasterias, II 115
Dichotomum, V 121
Dickiei, Staurastrum, V 3

var. circulare, V 5

- f. punctata, V 4

- var. rhomboideum, V 5

- var. semicirculare, V 5
Dictyosphserium, V 1!J8
Didelta, Cosmarium. II 15

Kuastrum, II 10, 15

- f. scrobiculata, II 17

- var. sinuatum, II 15
var. tatricum, II 15

- var. tvpicum, II 15
Heterocarpella, II 15

didymacanthum, Euastrum, II 81
didymocarpa, Schiznspora, I 7!i
didymocarpum, Closterium, I 181

iVniuin. I 11, 79

didymochondra, L'rsinella, ill 202
didymochondrum, Cosmarium, 111 262
Didymocladon, IV 119
Didymoprium, V 241
didymoprotupsum, C.'o.smarium, III

192

didymotoca, Arthrodia, I 117
didymotocum, Closterium, 1 116

- var. asperulatum, 1 118

- var. BailJyanum, I 117, 118
dim'cilc, Cosmarium, J 1 1 96

var. subla3ve, III 97
Diiritus, Closterium, I 64, 06
Xetrium, I 64

- var. constrict um, I 64
Penium, I 14, 64

- f. curta, I 04

- var. montanum, I 04

- f. recta, I 04

dilatata, C.oniocystis (Staurastruin),

IV 173

dilatatum, Closterium, I 121
Docidium, I 195

- var. subundulatum, I 190
Phycastrum, IV 173
Pleurotseiiium, I 100

- Staurastrum, IV 172

- var. alternans, IV 170

- var. extensum, IV 177

- var. hibernicum, IV 175

- var. iiidicum, IV 177

- var. insigne, IV 170

- var. obtusilobum, IV 173

- var. truncatum, IV 175
diplacanthum, Staurastrum, V 186

var. anglicum, V 186

280

INDEX.

diplospora, Cyliiidrocystis, I 11, 61 ;
V 260, 266

- var. major, I 61
diplosporum, Cosmarium, V 256

Penium, I 61

diplosporus, Calocylindrus, I 61
directa, Arthrodia, I 127
directum, Closterium, I 127
discretum, Cosmarium, 111 165

— Dysphinctium, III 165
dispar, Phycastrum, IV 187

— Staurastrum, IV 187
disputatum, Staurastrum, IV 176

- var. extensum, IV 177

- f. minor, IV 176

- var. sinense, IV 176
disticha, Ursinella, III 215
distichum, Cosmarium, III 215
Distribution of Desmids, I 12
dissiliens, Gloeoprium, V 229

- Hyalotheca, I 14 ; V 229

- f. bidentula, V 232

- f . circularis, \ 232

- var. hians, V 234, 237

- var. major, V 232

- var. minor, V 232

- var. tatrica, V 234, 237

- f. tridentula, V 233

- f. triquetra, V 233
divaricata, Helierella, II 42
divaricatum, Euastrum, II 42
docidioides, Cosmarium, V 268
Docidium, I 3, 9, 24, 193
doliforme, Cosmarium, III 49
doliolatum, Closterium, I 121
Donardense, Staurastrum, IV 169
dorsideiitiferum, Staurastrum, V 171
Double zygospores, 111
dovrense, Cosmarium, III 144
dovrensis, Ursinella, III 144
Duacense, Staurastrum, V 116
dubium, Euastrum, II 43

var. anglicum, II 44

- var. cambrense, II 45
var. Snowdoniense., II 45

- Staurastrum, V 112
Dysphinctium, I 24 ; II 126

eborafen.se, Arthrodia, 1 140

- Closterium, I 140

- var. achillense, V 262
( 'osmarium, IV 8

- Staurastrum, V 137
eboracensis, Spirotsenia, 1 42
echinatum, Staurastrum, A" 56
erhiiiodermum, Staurastrum, V 79
educta, Ursinella, 111 261

eductum, Cosmarium, III 261

— var. angustatum, III 266
Ehreiibergiaiium, Phycastrum (Pachy-

actinium), V 173
Ehrenbergii, Arthrodia, I 144

- Closterium, I 10, 14, 143

- var. Malinvernianum, I 145

— Docidium, I 205

var. elongatum, I 207

- var. granulatum, I 207

- var. tumidum, I 206

— Penium, I 205

— Pleurotaenium, I 205

- var. elongatum, I 207

- var. granulatum, I 207

- var. undulatum, I 207
Xanthidium, V 173

elegans, Arthrodesmus, IV 110

- Cosmarium, II 48 ; III 20
Didymidium (Euastrum) II 48
Euastrum, II 48

- var. bidentatum, II 39

- f. declivis, II 48

- var. inerme, II 24

- var. lobulatum, II 43

- var. Lundellii, II 48

- var. Nova3-Semlice, II 49

- var. ornatum, II 50

- var. ornithocephalum, II 50

- var. pseudelegans, II 49

- var. rostratum, II 35

- var. speciosum, II 39

- var. spinosum, II 38

- var. typicum, II 48
elegans, Genicularia, 1 36

Helierella, II 48

Heterocarpella, II 48
elegantissima, Pleurotwniopsis, IV 40
elegaiitissimum, Cosmaridium, IV 40

- Cosmarium, IV 40

- f. minor, IV 41
Elfvingii, Cosmarium, III 56

- var. altius, III 56
var. saxonicum, III 56

cllij)soidea, Ursinella, II 172
elUpsoideum, Cosmarium, II 167, 172
ellipticum, Euastrum (Cosmarium),
IV 7

- Spondylosium, V 222

- Staurastrum, IV 138
elobatum, Euastrum, II 54
elongatum, Docidium, I 104

- Staurastrum, I 14 ; V 156
emargiriato-constrictuii), Cosmarium,

III 189
Endlicheriana, Palmoglcea, I 56

- Mesotaaiimn, 1 56

var. caldariorum, I 53

INDEX.

281

Endlicheriana, Mesuttenium, var.

grande, I 57
endospira, Palmogloea, I 39

— Spirotaenia, I 39
Ensis, Closterium, I 117
entochondrum, Cosmarium, III 193
erasum, Staurastrum, 114; V 71
erectum, Didymidium (Staurastrum),

IV 91 ; V 7
erosa, Helierella, II 45
erostelluin, Staurastrum, V 72
erosum, Euastrum, 1 I 45

- var. notabile, 1 1 43
erythrocephala, Spirota-nia, I 41
Etchachanense, Cosmarium, III 170
Euarthrodesmus, IVT 89
Euastrum, I 2, 4, 11 ; IE 1
eugeneum, Doeidium, I 202

Pleurotaenium, I 202

- f. Cambrica, I 203

- f. Scotica, 1 203
eustephanum, Desmidium, \' 190

- .Staurastrum, V 190

- Stephanoxanthium, V 19o
Euxanthidium, IV 5o
exeavata, Istlmiosira, V 21 I
excavatum, Cosmarium, 111 147

- f. duplo-major, III 145. 148

- var. ellipticum, HI I is

- f. major, 111 \ \*
Dysphinctium, III 147

- Spheerozosma, \" 211, 21 1

- f. javani'-a, V 213

- var. Xova'-Semlia-, IV 1 10

- var. secedeiis, V 225

- var. subquadratum, \" 212
var. Wallichii, V 214

exigua, I'rsiuella, III 03
exiguum, Cosmarium, 1 1 1 63

- var. pressum, III 64

- var. subrectangulum, 111, 64
1'enium, 1 86

- f. Leuisii, 1 80

- f. major, I 14, 86
exik', Euastrum, II 57

Farquhargonii, Docidium, 1 205

- Staurastrum, IV 155
fasciculatum, Closterium, V 209

Didymidium (Xaiithidium), IV
75

- Euastrum, IV 75
Holacanthum, I\" 75

- Xaiithidium, IV 75

- var. «, IV 04

- var. ornatum, IV 75
var. Uronense, IV 77

- var. polygonum, IV 03, 75

fastidiosum, Cosmarium, III 218
fenestrata, Helierella, II 15
fenestratum, Cosmarium, II 15
filiforme, Onychonema, V 216, 218
filiformis, Isthmia, V 210

— Isthmosira, V 216

— Odontella, V 216

— Sphasrozosma, V 208
Tessararthra, V 210

iimbriata, Helierella, II 99

- 3Iicrasterias, II 99

- f. apiculata, II 98

- var. spinosa, II 100
h'mbriatum, Didymidium (Micras-

terias), II 99

ti^-iioi, Staurastrum, V 157
liavum, Cosmarium, II 170
foliatum, Staurastrum, V 134
fontigena, rrsiuella, II 147
fontigenum, Cosmarium, II 147
forcipatum, Staurastrum, V 3
forficulatum, Staurastrum, \' 187

- var. loiiLricoruc, \' 187
formosula, Uitjiuella, III 211
formosulum, Cosmarium, III 240

- var. XatliMi-stii, III 242
fractum, Closterium, I 117
franconicum, Didymidium (Stauras-
trum), V85

- Staurastrum, V 85
furcata, Helierella, II 113

- Mierasterias, 1, 4, 14 ; IL 102,

113

- var. deeurta, II 113

- var. deiitieulat i, II 105
var. expansa, II 113
var. gracillima, 1C 113
var. simplex, II 113

- var. typira, 1 1 1 13
furcatospermum, Cosmarium, 111 206
furcato-stellatum, Staurastrum, V 194
furcatum, A.steroxanthium, \' 173

Didymidium (Micrasterias), var.
furcatum, II 113

- Staurastrum, V 173, 170

- var. armigerum, V 174, 191

- var. candianum, V 175

- var. seiiarium, V 175

- var. subsenarium, V 175

- Xanthidium, IV 51 ; V 173
furcigerum, Asteroxantliium, V 189

Didymidium (Staurastrum), V

189

Didyuiocladon, V 189
Phycastrum, V 189

- (Amblyactinium), V 18J

- Staurastrum, V 188, 195
f. arniiuera. V 191

282

INDEX.

i'urcigerum, Staurastrum, f. eusto-
pliana, V 190

- var. rcductum, IV 111); V
192

fusiiormis, Spirotaniia, I 43

galeatum, Staurastrum, V 113

ualerita, Ursinella, II 194
galeritum, Cosmarium, II 194

galieiense, Closterium, 1 142
(larrolense, ( 'osmarium, III 12
(.'atniense, Staurastriim, V 32
(iayana, I'rsinella, IV S
(iayauum, ( 'osniariuin, I V 7

var. eboracense. I V 8
(Jayii, ( 'osmarium, IV 8
gemelliparium, Staurastrum, V 176
uciniiiata, I'rsinella, 111 177
geminatum, Cosmarium, III 177
ucmmata, llelierella. 1 1 03
geminatum, Cosmarium, l[ 03

Kuastrum, II 63

var. typieum, II 03
geminifera, I'rsinella, I \" ,">
ue m m item m, ('osniariuin, IV 5
(uMiicularia, I 2. 24, 2f>. 35
geometrieum, ('osniariuin, 1 1 1 67
Gerstenbergii, Cosmarium, 111 100
glabrum, Desmidium, V '2

IMiycastruin, V '2
• L'hyeastrum (Stenactiiiiuin) Y '2

Staurastrum, \' 2

Xanthidium, I\' 72
-ladiosuin, Staurastrum, V .">4, 57

- var. dclieatuluin. Y 58
glaucescens, Arthrodesmus, \Y 103

- f. convcxa. I Y !<>.">
ulohosuni, ('osniariuin, II I 29

- f. minor, 1 1 1 :>(>

\ ar. minus. III 30

- subsp. subarctoum, III .">!
I )ysphinctium, 1 1 1 2!>

var. minus, 1 1 1 30

- f. subviriile. Ill 114
(Jonato/yua-, I '2~>, 29
Gonatozygon, 1 1, 2, 24, 2r>, 29
u'onioidcs. ('osmarium. 111 111

- var. subturgidum, III 112
\ar. variolatuni, 111 112

gotlandicunij Cosmarium, III 54
var. I'ambrense, 1 1 1 ,").">

grarilo, ClosttM-ium. 1 166, Mil)
var. elon.u-atum. I 168

- f. irracillima, I 174
\ ar. tt-nue, 1 168

- f. tenuissima, I I(i7

I >id\ midium (Staurastrum), V (JG
1'hy east rum, Y 90

gracile, Staurastrum, V 96, 103

- var. bicorne, V 98

- var. bulbosum, V 98

- var. coronulatum, Y 100

- var. cyathiforme, V 99

- var. nanum, V 100

- var. tenuissima, Y 100
gracileps, Desmidium, V 253
gracilis, Arthrodia, I 107
gracillima, Spirotienia, I 47
gracillimum, Staurastrum, var. bi-

radiatnm, V 119, 120
uradatnm, Cosmarium, 111 241
grauata, tirsinrlla, 11 187
granatum, Cosmarium, II 186

- var. eoncavum, II 187

- var. rlongatuni, 1.1 189

- var. Grunowii, II 189

- var. subgranatum, II 188

- var. typicum, II 18(>
Didymidium (Cosmarium), II ISO
iMiastrum (('osmarium), 11 ISO

Brando, Pleurenterium, IV 140

- Staurastrum, IV 120, 140

- var. parvum, IV 141
(irantii, Cosmarium, IV 38
granulata, Mirrastcrias, 1 1 SS
granulatum, Cosmarium, III 164

Docidium, I 87
Penium, I 87

- Spha-ro/osma, Y 213

- var. trigranulatum, V 214
i^ranulatus, Arthrodesmus, l\" 100

- CloshM-ium, L 21!)

IVnium (IVtnuMnorus). 1 219
TetnuMnonis, I 14, 219

- var. attenuates, 1 221

- f. minor, I 221
granulosum, Desmidium, IV 1SS

- Staurastrum, I V 188 ; V 29

- \ ar. aeutuin, I \' 189

- f. eonnexa, 1 Y 189
granulusculum, Cosmarium. Ill 112
Gregorii, Cosmarium, 111 232

var. papillit'erum, 1 1 1 233
(iivvillii, Desmidium, \' 2.10

Didymoprium, \' 2.~>u
Griffithii, Closterium, I 191
Griffithsianum, IMiycastruin (I'aehy-
artinium), Y 7S

- Staurastrum, \' 78
(Jymiiozyga, I 2 : Y 241, 254

llaaboeliense, Staur.ist I'um, Y 140
liamata, Micrasterias, II 90

- f. Brasilicnsis, II 90
Hammeri, Cosmarium, II 181

— var. Uiberuieum, II 184

INDEX.

283

Hammeri, Cosmarium, var. homalo-
dermum, II 182

var. oetogibbosum, III 52

- var. protu be rans, 1 1 183

- var. retusiforme, II 180

— Didymidium (Cosmarium) var.

majus, II 181
Hammeri, Euastrum, II Is I

Ursinella, II I M
Hassallianum, Euastrum (Eucosma-

riuin), II 03

llaynaldii, Penium, I ss
Heimerlianum, Staurastrum, V 165

var. spinulosum, V 165
Heimerlii, Cnsmariuni, III 74

- var. tumidum, 1 1 1 74
helcangulare, CoMnarium, 1 1 1 68

hclcan-.'ularis, I "rsinclla, I I I OS
Hdierella, II 2, 77
llermanniana. I )id vmidium (.
terias), II 122

— Micrastcrias. I I 122
llcutlcrianum, Cnsmariuni, V 200
hexacant hum, Staurasi rum, V 15
hexaceros, Dcsmidium. V 138
hcxaccrum, I'h vcast rum, \' I3S

- .Staurastrum. V 1 12, 138

- var. /}, V 1 1 1

- var. ornatum, \' 120

- vai-. scmidrcularc, \' 139
vai-. scmilmiarc, \' 130

hexagonum, Cosmarium, 111 50

Staurastrum, I V 122
Xanthidium. I \' 8(i
hexagonus, Arthrodesmus, IV M'.

vai1. polmiica. I \" S7

- var. tumida, I V 117
hcxaloba, Ui'sinclla, III 257
hexalo bum, Cosmarium, III 257

var. minus, 1 1 1 258
hcxastidia, Crsinella, III I 13
hexastichum, Cosmarium, III 143

- var. octastidium, 1 1 I I 13

- var. polystiduim. Ill 144
Hibernicum, Cosmarium, III 114
hibernicum, Staurastrum, 1\' 150

var. Kan|uhar.sniiii, I V 155
I Lolacanthum, IV 4<S
llolmiense, Cosmarium, III 1

var. attenuatum, II I 4

var. hibernicum, JII 01

var. intcgrum. 111 2

var. Lundellii, III 1

- var. minor, III 4

- var. Nordstedtii, II 1 I

- var. undatum, I1J 4
Dysphinctium, lit 1

var. iutegrum, 111 3

Holmiense, Euastrum (Cosmarium),

III 1

1 1 nlmiensis, Ursinella, ill 1
Holocystis, II 77
homaloderma, Ursinella, II 182
homalodermum, Cosmarium, II 182

• var. rotundatum, II LSI'
bomoeacanthum, Xanthidium, V 59
horametrum, .Staurastrum, V 51
humorosa, Holierella, JI !i
humerosum, Euastrum, II 8

• var. genuimim, 1 1 !»
liumile, C'osmarium, III 221

\'ar. daniciim, III 224

• var. glabrum, 1 1 1 225
var. striatum, II 1 223
var. subdanicum, III 122
var. siib.stri.-itum, I 1 1 224

Kuastrum (Cosmarium), 111 221
liumilis. ('rsinclla. I 1 1 222
Hutcbinsoniij Dnn'dium, I 214

Pleurotaenium, I 214
Myacintbi, < 'nsmai'inm, I V 7
Hyalotheca, 12: \' 228
Hy>tri\, I)idymidium (Staiirastnim),
15. majus, V .V.I

A. minus, 0 id raironum, \" .'57

- a trigommi, V (id
- Staurastrum, \' 60

is, | -27), -21
idiosporum, Closterium, I 180

imprcssula, Ursinella, III si I
imprcssiiliim, Cosmarium, III 86

Euasti-iim (Cosmarium), 1 1 1 80
incavata, I Idicrclla, II 58
im-avatum, Euastrum, II 58
iiM'onspicuum, ( 'o^marium, II 164
Dysphinctium, \' 207
IVnium, 1 101 ; V 261, 267
- Staurastrum, IV I .'51, V 86

- var. erassum, V 87
incrassatus, Arthrodesmus, l\" 5,S
im-iii'vum, Closterium, I 136
Incus, Arthrodesmus, IV S'.i. 90

- var. americanus, IV 110

- var. divorgens, I\' !H
var. indentatus, IV 94

- var. intennedius, V 13

- var. longispinus, 1\' 96

- f. minor, IV 92

- f. perforata, IV 93

- f. quadrata, IV 07
var. Ralfsii, IV 95
f. rotundata, IV 07

var. subquadratus, 1\ 97
var. subtriangularis, IV loo
-- var. triangularis, l\r 07

284

INDEX.

Incus, Arthrodesaius, f. typica, IV 91
— var. validus, IV 96

- f. minor, IV 105

- var. vulgaris, IV 95
Binatella, IV 90

- Cosmarium, IV 91
Heterocarpella, IV 90

- Staurastrum, IV 90
Iiiclica, Hyalotheca, V 234, 237
inelegans, Staurastrum, IV 153
ineptus, Arthrodesmus, IV, 115
inermc, Euastrum, II 24

- var. aboense, II 23

- var. Lundellii, II 24

- var. Ralfsii, II 24
inermis, Helierella, II 24
inferum, Dysphinctium, III 22
inflatum, Staurastrum, IV 191

tjnflexum, Staurastrum, V 108, 136
inornata, Ursinella, IV 31
inornatum, Cosmarium, IV 31
insigne, Didymidium (Euastrum), II

31
Euastrum, II 31

- var. elegans, II 31, 32

- var. intermedium, II 33

- var. mammillosum, II 31

- var. montanum, II 31, 32

- var. typicum, II 31
Euastrum, [I 33

insignis, Helierella, II 31
insulare, Cosmarium, II 09
Euastrum. II 68

- var. parvum, V 265
intermedia, Arthrodia, I 125

Helierella, II 33
Holocystis, II 33
Ursinella, III 138
intermedium, Closterium, I 125

- var. di rectum, I 127

- var. liibernicum, I 126
var. juncidtim, I 128
var. sculptum, I 126

- f. eboracensis, I 127

- var. typicum, I 120

- Cosmarium, III 138
Euastrum, II 33

- Stauroceras, 1 180
interruptum, Closterium, 1 08

Netrium, 1 68

- var. sectum, I 69
Penium, I 08

interstitiale, Euastrum, IV I
iotanum, Staurastrum, V 121
irregulare, Cosmariuni, III 188

Staurastrum. V 150
isthmium, Co.smarium, III 145
. f. hibernica, III 146

isthmium, Cosmarium, var. Willei,

III 148

isthmochondria, Ursinella, III 174
isthmochondrium, Cosmarium, III

173

- var. pergranulatum, III 175

Jacobsenii, Cosmarium, II 172
jaculiferum, Staurastrum, I 14 ; V 16

- var. excavatum, V 18

- var. subexcavatum, IV 89 ; V
18

jenisejense, Cosmarium, III 175
jenisejensis, Ursinella, III 175
Jenneri, Arthrodia, I 135

- Closterium, I 134

- var. crassum, I 130

— var. liibernicum, V 262

- var. robustum, I 136

- Cylindrocystis, 1 77 ; V 260
Euastrum, II 22
Helierella, II 87

- .Micrasterias, II 86

- f. Brasiliensis, II 88

- var. simplex, II 88
Penium, I 77 ; V 260, 261

- Staurastrum, V 147
juncida, Arthrodia, I 128
juncidum, Closterium, I 128

— var. j3, I 129

- var. brevior, I 129

- var. elongatum, I 130

Kinahani, Gonatozygon, I 30, 35

Leptocystinema, I 35
Kirchneri, Cosmarium, III 203

Helierella, II 50

- Spirotsenia, I -1 1
Kitchellii, Staurastrum. V 178
Kjellmani, Cosmarium. UJ 219

var. grande, 111 221

- var. ornatum, 111 220

- (lonatozygon I 33

- f. minor, I 34

- Staurastrum, 1 14 ; IV 182

- var. rotundatum, IV 191
Ursinella, III 2111

Klebsianum, Cosmariuni, 111 2L1
Rlebsii, Cosmarium, 11 193
Kramstai, Mesotsenium. I 57
Kutzingii, Arthrodia, I 180

- Closterium, 1 186

- var. vittatum, I 188

, Closterium', 1 222
- Cosmarium, II f 99

var. cymatium, 111 103
- var. octangularis. Ill 101

INDEX.

285

Iseve, Cosmarium, var. septentrionale,
III 102

- var. undulata. Ill 1<>1
Euastrum (Cosmarium), III 100

— Gonatn/.v^on, I 32

- Onyehonema, V 218

var. mirraeanthum, V 218

— Penitnn, I 222

- Stauraatrum, V 92, 157. 177

- var. C'levei, V 177
lands, Tetniemorus, I 14. 222

I'rsinHIn, III 100
la'vispinum, Staurastrum, V 90
lagenarioides, ('i»smariiiiii. \' 267

l>vsphiiietium, V 267

Pemuni, I 93; V 261, 267
La^iThciniii. St;iiirastnnn. V 144
Lagoense, Arthrodia, I 114

( 'losterium, I 114
laiuellosum, Closterium, I »'>4

I '••iiiuni, 1 64

lanceolata, Aithrodia, I 149
lanceolatum, Closterium, I 149
var. parvum, 1 150

- Staurastrum, JY 149

var. eompn-v>um. l"\" 150
Landmark!!, Staurastrum, \' 144
Laugii. Iviast rum. 1 1 I 25! i
laui:itum, Staurastrum, V .'!. 7

l,aj)c/\ nskii. Arthrodesmus, IV 111
lasiosporum, Cosmarium, ill 126
lata, tJrsinella, IV 15

laterale, Closterium, I 186
lateralis, Arthrodia, I 1st;
latereundatum, Cosmarium, 111 12
latieolle. I'luastrum, V 264
latifrons, Cosmarium. IV 33

Tisiiiclla, IV 33

latiusculum, Staurastrum, A* 124
latum, Cosmarium, IV 15

var. margaritatum. IV 18

- f. minor, I 14; I V 16
Leibleinii. Arthrodia, I 141

- Closterium, I 141

- var. /3, I 141

var. curtum, I 141*

- var. minus, I 136

- var. occidentale, V 262
leioderma, Ursinella, III IHH
leiodermum, Cosmarium, III 100

Euastrum (Cosmarium), III 100
Xanthidium, IV 72
Lens, Closterium, I 73

- var. intermedia, I 73

- var. minor, I 75
lepidum, Cosmarium, IV 33
leptacanthnni, Staurastrum, IV 119
leptodermum, Staurastrum, V 27

Leuronema, V 219
Lowisianurn, Staurastrum, IV !:?!>
Lewisii, Penium, I 86
Libellula, Closterium, I 73 ; V 261
Penium, I 73, 110 ; V 261
var. intermedium, I 74

- var. interruptum, I 74
limnetic-urn, Closterium. I ]f.7

vur. tenue, I 168
Linoa, Arthrodia, I 179

' 'lostorium. 1 173, 178
lincata. Arthrodia. I 181
linoatum, Closterium, 111. 181

var. /3, I Jsi'

var. saiidviccnsc, I 184

I. s|iirostriolat;i, 1 182
littoralc, ( 'losterium. I 155
littoralis. Arthrodia. I 155
lohatospnnim. Cosmarium, III 126
loljulatum. Kuastrum. 1 14; II 43
L'"-omot ion. I 7
Logiense, Cosmarium, ] 14: III 163

- f. expausa. IV 16

Arthrodesmus, \ 17, 18

Didymocladon, V 33
Staurastrumj I 14 : \" 33
var. l)i«lentatum. V 34
( Pleurenterium), Y 34
(Srhi/astrum), V 33
liiuatum. Staurastrum, V 29

var. planetonieum, V 30
var. suljarmatum, I V 188
Lundellii, Arthrodia, I 169
Closterium, I 169

- Cosmarium, II 138

var. .••thiopieum, 1 1 140

- var. con-upturn, II 139
var. elliptic-urn, II 138

I'] u a strum, II 55
Helierella, II 55
Spondylosium, V 224

\ -ar. triquetrum, V 225

- Ursinella, II 138
Lunula, Arthrodia, I 150

- Closterium, I 150

- var. biconvexum, I 152

- var. coloratum, I 152

- var. intermedium, I 152

- f. minor, I 151
var. typicum, I 150

Muelleria, I 150
Vibrio, I 150

maamense, Staurastrum, V 32, 75
macilentum, Arthrodia, I 118

- Closterium., I 118
macrococca, Palmoglcea, I 51
macrococcum, Mesotsenium, I 51

286

INDEX.

macrococcum, Mesotaenium, var.

micrococcum, 1 52
magnificum, Euastrum, var. cras-

soides, II 5
Mahabuleshwarensis, Helierella, II

121

- Micrasteiias, II 121

- A. genuina, a indica, II 122

- var. Wallichii, II 122
Malinverniana, Arthrodia, I 145
Malinvernianum, Closterium, I 145

- Cosmarium, III 199

- var. Badense, III 199
mammillosa, Helierella, II 31
mammillosum, Euastrum, II 31
Manfeldtii, Staurastrum, V 114, 168

- var. annulatum, V 115
margaritacea, Cylindrocystis, I 83
margaritaceum, Closterium, I 83

Didymidium (Staurastrum), V

131
Penium, I 24, 83

- var. punctatum, I 88, 90
Pentasterias, V 131
Phycastrum, V 131

- (Stenactinium), V 131

- Staurastrum, I 14 ; V 131

- var. coronulatum, V 132

- var. hirtum, V 133

- var. inflexum, V 108

- var. ornatum, V 111, 133

- var. robustum, V 133

- var. subcontortum, V 134

- var. truncatum, IV 175
margaritatum, Cosmarium, IV 18

- f. subrotundata, IV 19
margaritifera, Helierella, III 199

- Micrasterias, III 199
margaritiferum, Cosmarium, III 160,

199

- f. confusa, III 203

- f. genuina, III 157

- var. geiiuinum, III 199

- var. incisum, III 159
f. Kirchneri, III 203

- f. regularior, III 203

- var. reniformis, III 157
Didymidium (Cosmarium), III

199

Euastrum, III 199
maximum, Docidium, I 213
Pleurotsenium, I 213

- var. occidentale, I 212
megacanthum, Staurastrum, V 20

- var. scoticum, V 21
megalonotum, Staurastrum, V 182

- f. hastata, V 77

" forma,'1 Nordst. V 185

melanospora, Ursine! la, II 162
melanosporum, Cosmarium, II 162
melitensis, Micrasterias, II 113, 116

— var. gracilior, II 113
Meneghinianum, Dysphinctium, III

Meneghinii, Cosmarium. Ill 90

- " forma," II 58

var. angulosum, III 93
var. concinnum, III 95

- f. crenulata, II 150

- var. genuinum, III 91

- f. Isevis, III 95

- f. latiuscula, III 92

- var. nanum, III 93

- f. octangularis, III 101

- f. Reinschii, III 86

- f. rotundata, III 97

- var. simplicissimum, III 86,
100

- var. subhexagonum, III 100

- f. tricrenata, II 150

- f. vulgaris, III 91

- var. Wollei, III 52
Meneghinii, Euastrum (Cosmarium),

III 91
Ursinella, III 91

Meriani, Didymidium (Staurastrum),

IV 122"

- Staurastrum, IV 122 ; V 269

- f. constricta, IV 122

- f. rotundata, IV 124
mesochondrium, Cosmarium, III 242
mesoleium, Staurastrum, V 196
Mesotaenium, I 1, 2, 3, 24, 26, 48 ;

V239

Micracanthum, IV 50
Micrasterias, I 2, 4 ; II 76
micrococca, Palmoglcea, I 52
micrococcum, Mesotaenium, I 52
micron, Staurastrum, V 123
microsphincta, Ursinella, II 156
microsphinctum, Dysphinctium, II
156

- Cosmarium, I 14 ; II 156

- var. ma jus, II 157

- f. parvula, II 157
minimum, Cosmarium, III 66
minor, Schizospora, I 79
minus, Cosmarium, III 173
minuta, Spirotsenia, I 41

- var. eboracensis, I 42

- var. minutissima, I 41

- var. obtusa, I 41
minutissima, Cylindrocvstis, I 62; V

260

minutissimum, Cosmarium, III 47,
126

INDEX.

287

minutissimum, Didymidium (Stau-

rastrum), IV 130
Euastrum, II 57
h-iiium, I 81

- Staurastrum, IV 130, 131 : V 80

var. oonstrictum, IV 132

- var. convoxum, IV 131
minutum, Cosmarium, III 7t>

Docidium, I 101 : V 2»'.s
Dysphinetium, I 102 : V 2r,s

- ( ionati'/.vLmn, I 33
Penium, 1 101 ; V 261. 268

var. alpinum, I 104
var. crassum, I 105

- var. elongatum. I 104
var. iirarile, 1 103

- f. major, I 103

- f. minor, I 103

- var. pnlonirum, I 105
var. tuinidum, I 104
var. midulatum. I 105

Plriimta-niuni. I I'll'
minutus, Calocylindrus, i 1 02

Tetmemorus, J 223
minfica, Palmoglu-a, I 5O
mirifieum, .Mes<>ta?nium, I 50
.Mittaliii, ( 'nsmarium, 1 1 151
monile. Spc>nd\ losiinn, \" 221. 22s
monilitna. Arthrodia. I ML'

Luntilina. I 141*

moniliferum, ( 'losterium. I 7. lo. 142
var. genuinum, 1 142

- f. Leibleiniana, 1141

- f. heibleinii. I 141
var. typicum, I 142

Staurastrum, LV 177
monilifonne, Cosmarium, II 171 ; III
20

- var. a, III 30

- f. elliptica, II 171

- f. elongata, 1 1 1 23

- var. linmeticum, III 23

- f. panduriformis, III 22

- f. punctata. III 22

var. subpyriforme, III 23

- f. subviride, III 114
Diplosphserium, III 21
Dyspbinctium, III 21

moniliformis, Gymnozyga, V 255

- var. gracilescens, V 256
— Scenedesmus, III 21

Tessararthra, III 21

Tessarthronia, III 20

Trochiscia, III 21

Ursinella, III 21

monochondrum, Cosmarinm, III 103
monomaza, Ursinella, III 140
monomazum, Cosmarium, III 140

monomazum, Cosmarium, var. poly-

mazum, III 140
monotsenia, Arthrodia, I 163
monotsenium, Closterium, I 163

- Gronatozygon, I 30

- var. pilosellum, I 31
montanum, Cosmarium, III 39

var. Pseudoregnesi, III 39
Euastrum, II 2, 58 ; V 265
monticulosa, Binatella, V 1M5
monticulosum, Phycastrum, V 183
Staura.-trum, Y 183
var. bifarium, V 184

- var. diplacanthum, V 18(>
var. groenlandicum, V 185
var. pulchrum, \' 185

- Stephanoxanthium, V 183
Mooreanum, Cosmarium, V 266

Dvsphinc-tium, \" 2ii('»

Penium, I 80; V 266
nioixa. Micrastt'rias. 1 1 1 18
morsum, Didymidium (Micrasterias).
II 118 '

- Cosmarium, II 157
iimcosa, Conferva, V 235

Hvalnthera, V 230,235

v

var. minor, \' 236
mucosuni, Desmidium, \' 22!)

- Gloeoprium, \' 235
tniici'iinata, Goiliocysti-- (Trigonu-

cystis), \ 1 1
HeliereUa, II 79

- Micrasterias II 79
inucronatum, Phycastrum (Ambly-

actinium), V 11

- .Staurastrum, V 7, 9, 11

- var. subtriangulare, V 12
Tetrachastrum, II 79

multilobatum, Euastrum, II 10
munitum, Staurastrum, V 193
muricata, Binatella, V 67
— Goniocystis (Trigonocystis), B.

rugosa V 67
muricatum, Phycastrum, V 67

Phycastrum (Amblyactiiiium), V
67

- Staurastrum. I 14 ; V 65, 60, 67,

132

- var. acutum, V 68
Murrayi, Micrasterias, II 93

- var. triquetra, II 94
musicola. Spirotsenia, I 39
mutica, Binatella, IV 133
muticum, Didymidium (Staurastrum),

var. Bieneanum. IV 130

- Staurastrum IV 133

- var. Bieneanum, IV 130
— var. brevispinum, IV 145

288

INDEX.

muticum, Staurastrum, var. depres-
sum, IV 135

- var. ellipticum, IV 134

- var. minor, IV 135

- var. subsphcricum, IV 138

- var. typicum, IV 134

Nsegeliana, Ursinella, III 14
Naegelianum, Cosmarium, III 14

Didymidium, V 47
Nsegelii, Netrium, I 66

Penium, I 66
nasuta, Ursinella, III 259
nasutum, Cosmarium, III 259

- var. asperum, III 261

- f. granulata, III 260
natator, Staurastrum, V 14-9
Nathorstii, Cosmarium, III 242
Navicula, Closteriura, V 262

Penium, I 75, 110 ; V 261, 262

- var. crassum, I 76

- var. inflatum, I 77
var. Willei, I 76

Navigium, Penium, I 64
neglecta, Hyalotheca, I 9 ; V 238
neglectum, Staurastrum, V 111, 139
nephroideum, Cosmarium, III Ki7
Netrium, I 24, 26, 63 ; V 261
Netzerianum, Cosmarium, III 159
nitens, Spondylosium, I 9
nitidula, Ursinella, II 197
nitidulum, Cosmarium. II 197

- f. punctulata, II 197

• Euastrum (Cosmarium), f. gcn-

uina, II 197

nitidum, Staurastrum, V 47
iiobile, Docidium, I 196

Pleurotsenium, I 196
nodosa, Docidiopsis, I 214
nodosum, Closterium, I 214

Docidium, I 214

- var. anglicum, I 215

- var. dentatum, I 214

- var. Hibernicum, I 214

- var. typicum, I 214

— Pleurota?nium, I 14, 214

- Staurastrum, V 88
nodulosum, Docidium, I 200

- var. labiatum, I 202

— Pleurotsenium, I 200

- var. ooronatum, I 199
Nordstedtiaiia, Ursinella, II 147
Nordstedianum, Cosmarium, II 146

— Onychonema, V 216, 218
Nordstedtii, Staurastrum, V 47
Norimbergense, Cosmarium, III 52

- f. depressa, III 53
f. obliqua, III 51

Norimbergense, Didymidium (Cos-
marium), III 52

Norimbergensis, Ursinella, III 52
notabile, Cosmarium, III 15

- f. media, III 17

- f. minor, III 16
Didymidium (Cosmarium), III

is'

Dysphinctium, III 15
f. minor, III 17

- subsp. speciosum, III 248

• Penium (Sphinctopenium), III 15
Notarisii, Staurastrum, V 55
Novse-Semlire Cosmarium, III 35

- var. polonicum, III 39

- var Sibiricum, III 36

• Ursinella, III 35
Nucleus, I 6

Xymanniana, Ursinella, II 184
Nymannianum, Cosmarium II 184

obcuneatum, Cosmarium, III 110
obesa, Cylindrocystis, I 60 ; V 260

Helierella, II 29
obesum, Euastrum, II 29
obliqua, Ursinella, III 49
(tbliquum, Cosmarium, III 49

- f. minima, III 51

- var. trigonum, III 51

- Nothocosmarium, III 49
oblonga, Echinella, II 12

- Eutomia, II 12
oblongiforme, Euastrum, II 12
oblongum, Cosmarium, II 12 ; III 114

Didymidium (Euastrum), II 13
Dysphinctium, III 114
Euastrum, II 12

var. cephalophorum, II 14

- var. depauperatum, II 15

- f. genuinse, II 13

— var. integrum, II 15

- var. oblongiforme, II 13

- f. scrobiculata, II 14
Netrium, I 66

- var. angustatum, V 261

- var. brevius, V 261

- var. cylindricum, I 67
Penium, I 66

oblongus, Calocylindrus, III 114
obscura, Spirotaenia, I 44
obsoleta, Ursinella, II 133
obsoletum, Cosmarium, II 133

- var. angustatum, II 135

- f. galiciensis, II 135

- var. Sitvense, II 134
Didymidium (Cosmarium), II 133

obsoletus, Arthrodesmus, II 133
obtusa, Arthrodia, I 107

INDEX.

289

obtusa, Iloya, L 107 : V 2r,n

- var. montaaa. I. 108
obtusatum, ( 'os.marium, III 7

- var. Beanlandii, [118
(tbtu-nm. Closterium, I Hxi. in?, 108

var. major, I Io7

- var. typirum, I l'»7
occidentale, Desmidium, V 245

Kii.tstnim. II 2. 67 ; III 191
occultum, CosmaTium, III _."..".
< >'-«-urrem-e of Desmids. I 12
ocellatum, Cosmarium, II 144

- var. incTassatum. II 144
o«-htli»d<->. ( iismarium, I \' 10

\ ai . amoebo-granulosum, I \'
12

\ ar. amo-bum. I V 11
t. granulosum, 1 V I 1
\ ar. "btu-atum. 1117

- var. subcin-ulan-. I V 12
rr.-in.-lla. I\' Id

(Ma.-aiithiiuu. IV S9
octacanthiini. Kua^trum. I V 111
octofurne. Didymidium (Xanthi-
dium), IV HI
Kiia-trum. I \" 111

- Staurastrum. IV I I I
Xamhidium, I \' III

var. major. I V ti-J

- f. minor. l\' 111
oi-tnci.nii^. Arthr«nl«^inii>. I V 111

- t. iinpai-. I V 1 K5

- var. major. I V til . (12

- Mirra-tcrias, IV 111
octogibbosum, Cosmarium, III ~>-

- var. iiulica, 11 1 ~>'2
odontopleurum, Cosmarium, III >t4
oligacanthum, Staurastrum. \' 48

- var. iucisum, \' 49
()lii_roiioiiLrnis, Cosmariuni. Ill 194

[Jrsinella, HI H'-t
O'.Mearii. Staurastrum, I \" Ml : V 13

\ ar. miniitum, \" 14
Onyrhom-ma. T 2 : V 2()7, 215
o icardium, V 203
Opliiura. Staurastrum. 114; ^' 153.

- var. cambric-urn, V 154
i'liii-ulare, Desmidium. l\ \~>~>

Didvmidium (Staurastrum), IV

1 .-).S

Phycastrum, IV 155
- Staurastrum, IV 155

- var. Bieneanum, IV 136
var. depressum. IV 158
var. extension, IV 158

- f. major. IV 1 .")»'•
var. hibemicum. IV 156

VOL. V.

• •1 liieulare, Staurastrum, f. major, IV
157

- f. pimrtata, IV 156

- var. Kalfsii. IV 156
orbicularis. Goniocystis (Trigono-

cystis), l\ 155
nrbiculata. 'IVssararthra. Ill 149

I'rshu'lla, III 149
orbiculatum, Cosmarium, III 149; 165

- t. major. TIE 150

I )\-s|)liiiictium. I LI 149

Penium. Ill 149
Orcadense. Xatithidium, IV 84
ordinatum, Cosmarium. l\" :\~>
tiruata, I'rsiuella, III 152
oriiatissimum. Ct»marium. Ill 259
ornatum. Cosmarium, III 151
var. aiiglica. 111 152

— var. minor. III IM'

- var. polonk-um, III 182
var. protractum. Ill 1>«2
\ ar. sueci< a. 1 1 1 152

- Euastrum. 1 1 1 152

- Staurastrum. V l.'j'i
..rnitlMM'rpliula. Helierella. II 5i »
omithocephalum, Euastrum, II 5n
orthogona, L'rsiiiella, III 1 1 s
(irthoifouuui, ('nsmarium. 111 15, 118
orthosticha. I'rsinella, II 1 His
iirthostichum, Cosmariuni, III 167

— var. compaction, III 169
var. ])umilum. III 169

oscitans, Euastrum (Micrasterias), II

7s

- MiVrasterias, II 78

- var. intermedia, II si '

- var. mucronata, II 79

- f. intermedia, II 80
var. pinnatifida, II 81

- var. typica. II ~S
Helierella, II 78
Holocystis, II 78
Tetrachastrum, II 78

osteonum, Staurastrum, V 197
ovale. Cosmarium, III 267

- var. subglabrum, III 269

- Cosmaridium, III 267
— Spondylosium, V 222

ovalis. Pleurotseiiiopsis (Cosmari-
dium), III 267
oxyacanthum, Staurastrum, V 169

- var. polyacanthum, V 170

pachyclerma, Schizospora, I 61

- UrsineUa, II 140
pachydermum, Cosmarium, II 139

- var. sethiopicum. II 140

— var. minus, II 196

19

290

INDEX.

pachydermum,Cosmarium, var. typi-

cum, II 140

pachyrhynchum, Staurastrum, IV 151
Palangula, Calocylindrus, III 108

- Cosmarium, III 108

- var. Debaryi, III 106

- var. genuinum, III 108

— Dysphinctium, III 108
Penium, III 108

palustre, Cosmarium, II 133

var. ovale, II 133

pandurans, Penium, I 83
papillifera, Helierella, II 91

Micrasterias, II 91 ; V 266

- var. glabra, II 93

- f. major, II 92

- var. varvicensis, II 93
papilliferum, Didymidium (Micras-
terias), II 91

papillosum, Sphserozosma, V 223

- Spondylosium, V 223

- Staurastrum, V 41
papulosum, Euastrum. II 63
paradoxum, Didymidium (Stauras-
trum), V 102

- Phycastrum, V 101, 119

- (Stenactinium), V 102

- Staurastrum. I 14 ; V 98, 101,

108, 119

- var. ciiigulum, V 105

- var. evolutum, V 107

- var. longipes, I 14; V 103,
107

- f. minor, V 106

- f. minutissima, V 106

- var. iiodulosum, V 106

- A^ar. parvum, V 106

- var. tetracerum, V 119

- Xanthidiastrum, V 218
parvula, Arthrodia, I 133

- Spirotsenia, I 43
Ursinella, III 110

parvulum, Closteiium. I 133

- var. angustatum, I 134

- Cosmarium, III 110

- var. pumilum, III 49

— Dysphinctium, III 110

- var. undulatum, Ill 49
paxilliferum, Staurastrum, IV 190
Pecten, Euastrum, II 12

— Helierella, II 13
pectiiiata, Helierella II 60

— Heterocarpella, II 60

. pectinatum, Cosmarium, II 60

Didymidium (Euastrum), II 60
Euastrum, II 60

- var. brachylobum, II 62
var. inevolutum. II 61

pectinatum, Euastrum, f. intermedia,
II 62

- f. typica, II 60

pelagic-urn, Staurastrum, I 13 ; V 124
Pelta, Euastrum, II 5

Penieae, I 26: 71
penioides, Tetmemorus. I 217
Penium, I 3, 71 ; V 261
peracerosa, Arthrodia. I 154
peracerosum, Closterium. I 154

- var. elegans. I 155
perforata, Ursinella, II 143
perforatum, Cosmarium, II 143

- var. typicum, II 143
pericymatia, Ursinella, III 34
pericymatium, Cosmarium. Ill 34

- var. eboracense. Ill 34
Dysphinctium. Ill 34

perissum, Cosmocladium, V 200
perpusillum, Cosmarium, III 88
Pertyanum, Cosmarium, III 144
Phaseolus. Cosmarium, II 158

- var. achondrum. II 177

- var. bioculatum, II 165

- var. elevatum, II 159

- f. minor, II 159

- var. typicum, II 158
Euastrum (Cosmarium). IT 158
Heterocarpella. II 158
Ursinella, II 158

phimus, Arthrodesmus, IV 104

- var. hebridarum, IV 105

- var. occidentals, IV 104
Phycoporphyrin, I 6
Phylogenetic relationships. Ill
Phymatodocis, I 25, 28
phymatosporum, Penium, I 91
pictum. Euastrum, II 41
Picum, Staurastrum, V 51
pileolatum. Staurastrum, IV 125,

127

- var. Brasiliense, IV 127, 128

- var. cristatum. TV 129
pilosellum, Staurastrum, IV 187
pilosum, Gonatozygon, I 34

Phycastrum (Amblyactinium), V

63
- Staurastrum, V 61, 63

- var. Brebissonii, V 62

- f. minor. V 66
pingue, Euastrum, I 14 ; II 30
pinguis, Helierella, II 30
pinnata, Helierella. II 10
pinnatinda, Didymidium (Micras-
terias). II 81

Holocystis, II 81
Micrasterias. TI 80
var. trigona, II 82

INDEX.

291

pinnatifulum, Euastrum, II 80

— Tetrachastrum, If XI
pinnatum, Euastrum. II 10

var. intermedium, II 9

— var. typicum, II 10
Placodermoe, I 26, 70
Plankton, I 13, 10

plnnum, Spondylosium, I 10 : Y 222
platyisthmum, Cosmarium, 111 127
Pleurenterium, I 24: IV 118. 119
Pleun.h.-niopsis, 1 24 ; II 126
I'l'-urotienium, I 3. 24, 197
plicatiim. < 'osmarium, II I 60
var. decedcns. 1 1 1 4.'5

- var. hibernicum, III 61

- f. major, 1 1 1 60

- var. minus, 1 1 1 44
var. Sroticum, III <>l

- var. sinuosiini, 1 1 1 44

— Didymidium (Cosmarium), III on
Pokornvanum, Cosmarium, II 190

Euastrum, II inn
])olare, Kuaslnim. I I lint
puloiiicum, I'enium, I !(»."»
p»lygona, Ursinella, III 70
polygonum, Cosmariuin, 1 1 1 76

Kuastrum (Cosmarium), III 70

- Xanthidium, I V •', \
polymazum, Cosmarium, III 1-ln
polymorphum. ( 'lustcrium. I HO

- ( 'osmarium, I '.)')
Didymidium (Staurastrum). Y

120, 129
Penium, I 14, 90

- t. alpicola, I DO

- var. Lundellii, I 90, 91

- Staurastrum, V 125, 12'.»

- var. braehycerum, Y 130
var. cyrtocrnim. V 135

- var. munitum, V 128

- var. pusillum, V 127
var. simplex, V 128
var. subgraeile, V 127

polytriehum, Ph vast rum, V 53

- Staurastrum, Y 53, 50

var. alpinum, V 5!>

- var. readingense, V 54
porrecta, Arthrodia, I 1 1 0
porrectum, Closterium, I 116

- var. angustatum, I 115, 116
Portiana, Ursinella, III 105
Portianum, Cosmarium, III 165

- var. nephroideum, III 167
— var. orthostichum. Ill 105

Portii, Leptocystinema, I 31
praegrande, Cosmaridium, III 150

- Cosmarium, III 150

— PleurotseniopsiS; III 150

VOL. V.

prselonga, Arthrodia, I 104
praelongum, Closterium, I 164

- f. brevior, I 165
prsernorsum, Cosmarium, III 196

— var. gallicum, III 197

- var. germanicum, III 199
var. soandinavicum, III 197

Preservation of Desmids, I 15, 17
rringsheimii, Staurastrum, var.

duplo-major, V 53
Pritchardiana, Arthrodia, I 172
Pritchardianuni, Closterium, I 172

- vai-. minus, I 173
proboscidium, Staurastrum, V 129

- var. subglabrum, V 129, 130
prominula, Ursinella, IV 46
prominulum, Cosmarium, IV 46

- var. subundulatum. IV 47
promoiitorium, Cosmariuni, IV 34
proiia. Art Iirodia. 1 !".'>
proiium, Closterium, I 173

- var. acutum, I 177

- f. brcvius. \" 264
var. ( 'ornu, I 157

- var. Linea. I 179

- var. Pritehardianum, I 172

- var. typicum, I 173
Protoplasm, 1 .">

protractum, ('osmarium, IT 07; III
181

Didymidium (Cosmarium), III
182

Kuastrum (Cosmarium), III 181
protuberans, Cosmarium, III 69

- f. paludosa, III 70
pseudamcena, Ursinella, IV 31
pseudamoemim, Cosmarium, IV 31

- var. basillare, I Y 32
1 )ysphinctium, IV 31

pseudarctoides, Cosmarium, V 266
pseudarctoum, Cosmarium, III 32

Dysphinctium, III 33
pseudarctous, Calocylindrus, III 33
pseudatlanthoideum, Cosmarium, II

191
Pseudbroomei, Cosmarium, IV 22

- var. eonvexum, IV 23
pseudelegans, Euastrum, II 49

Helierella, II 49
Pseudincus, Staurastrum, V 13
pseudobiremis, Ursinella, III 77
pseudobiremum, Cosmarium, III 77
Pseudoclosterium, Closterium, I 106,

109

Roya, I 109
pseudoconnatum, Cosmaridium, III

27
— Cosmarium, III 26

292

INDEX.

pseudoconnatum, Cosmarium, var.

constrictum, III 29
var. ellipsoideum, III 28

— Dysphinctium, III 27
pseudoconnatus, Calocylindrus, III 27

- Pleurotseniopsis, III 27
pseudocrenatum, Staurastrum, V 75
pseudocuspidatum, Staurastrum, V26
Pseudodianse, Closterium, I 132
pseudoexigua, Pleurotseniopsis, III 65
pseudoexiguum, Cosmaridium, III 65

- Cosmaiium, III 65

- var. angustatum, III 65

- Cosmaiium (Pleurotaeniopsis), III

65

pseudofontigenum, Cosmarium, II 148
pseudofurcata, Helierella, II 113

- Micrasterias, II 113
pseudofurcigerum, Staurastium,V 191
pseudomargaritiferum, Cosmarium,

III 165
pseudonitidulum, Cosmarium, II 195

- var. ma jus, II 160

- var. validum, II 196
pseudopelagicum, Staurastrum, I 14 ;

V 107, 125

- var. bifurcatum, V 107
pseudoprotuberans, Cosmarium, III

82

- var. alpinum, III 83
var. Kirchneri, III 82

— Ursinella, III 82
pseudopyramidata, Ursinella, II 201
pseudopyramidatum, Cosmarium, II

201

- var. minus, II 201

- var. stenotum, II 202
var. variolatum, II 203

pseudoralfsii, Cosmarium, IV 122
Pseudoregnesii, Cosmarium, III, 39
pseudorthopunctatum, Cosmarium,

III 179

Pseudosebaldi, Staurastrum, V 113,
116

var. bicorne, V 117

subsp. duacense, V 116

- var. simplicius, V 114
var. tonsum, V 117

pseudostreptonema, Desmidium, V

244
pseudotetracerum, Staurastrum, V

122, 124

pterosporum, Staurastrum, V 14
pulchella, Helierella, II 46
pulchellum, Cosmocladium, V 200
Euastrum, II 46

- var. retusum, II 47

— Sphserozosma, V 227

pulchellum, Sphserozosma (Spondy-
losium), V 226

— Spondylosium, V 227

- var. pyramidatum, V 228
pulcherrima, Ursinella, III 245
pulcherrimum, Cosmarium, III 245

- var. truncation, III 246

- var. typica, III 245
pulchrum, Sphaerozosma, var. planum,

V 222

- Spondylosium, V 223, 224, 245

- var. planum, V 225

- var. triquetrum, V 225
punctulata, Ursinella, III 207
punctulatum, Cosmarium, III 206

— var. brasiliense, III 211

— var. granulusculum, III 212

- var. Klebsianum, III 211

- var. ornatuni, III 211

- var. regulare, III 211

— var. rotundatum, III 211

— var. subpunctulatum, III 209

- var. typicum, III 207

- Cosmarium, III 170
Didymidium (Staurastrum),

180

- var. majus, f. alternans,
170

- Staurastrum, IV 179

- f. contorta, IV 180

- var. coronatum, IV 184

- f. elliptica, IV 186

- var. Kjellmani, IV 182

- var. muricatiforme, IV 186

- var. pygmaeum, IV 184

- f. trilineata, IV 185

- var. striatum, IV 186

- var. subproductum, IV 182

- var. subrugulosum, IV 167

- var. turgescens, IV 167
pungens. Staurastrum, V 44
purpureum, Mesota3nium. I 6, 55
pusilla, Arthrodia, I 162

- Ursinella, III 56
pusillum, Closterium, I 162

— var. major, I 163
var. minor, I 162

- var. monolithum. I 163

- Cosmarium, III 66

— var. retusum, III 66

— Cosmocladium, V 201
Euastrum, III 66

pycnochondra, Ursinella, III 244
pycnochondrum, Cosmarium, III 244
pygmsea, Ursinella, III 74
pygmseum, Cosmarium, III 73; V
221

- var. Schliephackianum, III 74

INDEX.

293

pygmseuin, Sphserozosma, III 73 ; V
220, 221, 225

- Spondylosium, V 220

• var. compression, V 221

• var. monile, V 221

- Staurastrum, IV 184

— var. obtusum, IV 180

• var. trilineatum. IV 186
pyramidata, Ursinella, II 199
pyramidatum, Cosmarium, II 199,

201

• var. angustatum, II 200

• f. intermedia, II 182

• var. stenonotum, 1 1 202

• var. typicum, II IHH
Didymidium (Cosmarium), II

199
Euastrum, II 72

- Staurastrum, V 68

• var. coilon, V 69

quadragies-cuspidata, Micrasterias, II

83
quadragies-cuspidatum, C< >si na ri u i n ,

II 82, 84
quadrangulare, Staurastrum, V 37, 38,

177

— f. major, V 37
quadrangulata, Ursinella, IV 2<>
quadrangulatum, Cosmarium, IV 26
quadratula, I'rsinella, III 121
quadratulum, Cosmarium, 111 121

- f. javanica, III i\'\
Euastrum (Cosmarium), HI 121

quad rat um, Cosmarium, III 57, 123

- var. angustatum, III 59
var. genuinum, III 58

- f. Willei, 11159
Desmidium, V 254

var. irracilis, V 253

— Desmidium (Didymoprium), V

2,54
Didymidium (Cosmarium), III

58

Didymoprium, V 254
Dysphinctium, III, 58

- var. Willei, III 59
Kuastrum (Cosmarium), III 58

quadriconmtum, Xanthidium, IV 59

- f. longispina, IV 56
quadridentatum, Cosmarium, I II 133
quadrifaria, Ursinella, III 141
quadrifarium, Cosmarium, Til 141

- f. hexasticha III 143

- f. octasticha, III 143

- f. polysticha, III 144
f. stellata, III 141

quadrimamillatum, Cosmarium, III

125

quadrispinatum, Staurastrum, V 38
Quadrum, Cosmarium, IV 20

• Ursinella, IV 20
quantillum, Docidium, I 206
Quasillus, Cosmarium, III 188

- var. quadrifera, f. polycrenata ,
III 240

• Ursinella, III 188
quaternaria, Pleurotseniopsis, III 204
quaternarium, Cosmarium, III 204
quinaria, Ursinella, III 216
quinarium, Cosmarium, III 216

- f. irregularis, III 217
ijiiiriferus, Arthrodesmus, IV 101

- f. compacta, IV 101

IJaciborskiana, Ursinella, II 137
Raciborskianum, Cosmarium, II 137
radiata, Micrasterias, II 113
rudiosa, Micrasterias, 14; II 95

— var. ornata, II 97

Ursinella, III 137
radiosum, Cosmarium, III 137
Ralfsii, Arthrodesmus, IV 95

- Arthmdia, I 183

— Calocylindrus, IV 43

- Closterium, I 182

• var. Delpontii, I 184

• var. hybridum, 111, 183, 186
var. typicum, I 183

1 'ismaridium, II 141

- Cosmarium, 114; II 141

var. montanum, II 142

- var. rotundatum, V 268

• var. typicum, II 141
Didymidium (Cosmarium), II 141
Dysphinctium, IV 43

• var. hexagonum, IV 122
Euastrum, II 27

- Gronatozygon, I 30

• Hyalotheca, V 235
Penium, I 101 ; IV 43

— Phyca strum, IV 170 ; V 89

— Pleurotseniopsis (Cosrnaridium),

II 141

— var. moiitana, II 142
ramosum, Asteroxanthium, V 77
Kavenelii, Staurastrum, V 70
rectangula, Ursinella, III 41
rectangulare, Cosmarium, III 54

— — var. cambrense, III 55

• var. hexagonum, III 56
rectangularis, Ursinella, III 54
rectangulum, Cosmarium, III 41
rectosporum, Cosmarium, II 197
rectum, Docidium, I 212

294

INDEX.

rectum, Peniuni, I 212

- Pleurotsenium, I 212
refractum, Staurastrum, V 86
Regelianum, Dysphinctium, I 97
Regnellii, Cosmarium, III 89

Ursinella, III 89
Regiiesi, Cosmarium, III 36

— var. montanum. Ill 39

- var. productum. Ill 38

- var. tritum, III 38

— Didymidium (Cosmarium), III 30

— Sphaerozosma, V 214
Ursinella, III 36

regulare, Closterium, I 122
regularis, Arthrodia, I 122
Reinschii, Cosmarium, III 12

- var. eboracense, III 13

— >Staurastrum, V 45, 46

- Ursinella, III 13
reniforme, Cosmarium. Ill 157

- var. apertum, 111 159

- var. compressum, III 158

— var. elevatuni, III 159
reniformis, Ursinella, III 157
repanda, Ursinella, III 53
repandum, Cosmarium, III 53

- f. minor, III 54

— Staurastrum, V 196
retusa, Ursinella, III 265
retusiforme, Cosmarium, II 180
retusum, Cosmarium, IV 91

- Cosmarium, III 265

- var. angustatum, III 266

— Euastrum, IV 91

- (Cosmarium), III 265

- Staurastrum, IV 160

- var. boreale, IV 160

- var. puiictulatum, IV 160
rliabdophorum, Staurastrum, IV 129
Robinsoniaiium, Xanthidium, IV 83

- Xanthidium, IV 84

roseola, Cylindrocystis, I 62 ; V 260
Rostaiiiiskii, Cosmarium, 111 251
rostellum, Staurastrum, Y 164

— var. erostellum, V 72
rostrata, Arthrodia, I 188

Helierella, II 35
rostratum, Closterium, I 188

- var. brevi rostra turn, 1 189

- var. Kuetzingii, I 180'

- var. setaceum, I 190

— var. typicum. I 188
Euastrum, II 35

- var. eumbricum, II 37
Rota, Euastrum, II 82, 99 102
rotata, Didymidium (Micrasterias), II

102
— Echinella, II 102

rotata, Eutomia, II 102
Helierella, II 102

- Micrasterias, I 8 ; II 102

- var. acutideiitata, II 102

- f. evoluta, II 104

- f. granulata, II 104

- var. pulchra, II 104
— var. uriiigera, II 104

rotundum, Cosmarium, II 139
Roya, I 3, 106 ; V 258
Royanum, Peiiium, I 88, 89

- Staurastrum, V 52
ruficeps, Closterium, I 130
rufescens, Penium, I 99
rufopellitum, Penium, I 99
rugulosum, Staurastrum, IV 178

Saccodermae, I 25, 29
Sarsii, Staurastrum, IV 102

- var. longispiiium, IV 95
Saxonicum, Cosmocladium, V 198, 202

- Staurastrum, V 54, 56

- f. tenue, V 63
scabrum, Staurastrum, V 81
scandinavicum, Penium, 1 88, 89
Scenedesmus, Cosmarium, II 176

- f. pimctata, II 176
Ursinella, II 176

Sccptruni, Closterium, I 193
Docidium, I 208
Pleurota?nium, I 208

var. capitatum, I 209
Sdiizacanthum, IV 48
Schizodesmus, IV 89
Schliephackeana, Ursinella, III 74
Schliephackeanum, Cosmarium, III
73

- f. spetsbergensis, II 163
scitum, Euastrum, III 259
scorpioideum, Staurastrum, var.

brevis, V 169
Scoticum, Closterium, I 161

- var. fusiforme, I 162

- Cosmarium. Ill 269

Sebaldi, Didymidium (Staurastrum),
V 166 '

- Staurastrum, V 166

- var. ornatum, V 114, 167

- var. productum, V 168
secodeiis, Sphaerozosma, V 225

- var. pulchellum. V 227

- Spoudylosiurn, V 225
semiradiata, Micrasterias, II 84
semiradiatum, Euastrum, II 84
senarium, Desmidium, V 175

- Staurastrum, V 175

- var. alpinum, f. tatrica, V 184
var. bifarium, V 184

INDEX.

295

seuariuin, Stephanoxanthium, V 175
Si-udteriana, Helierella, II 34
Sendteriaiium, Cosmarium (Euas-
trum), II 34

— Didymidium (Euastruui), II 34
Euastrum, II 34

var. latius, II 35

setacea, Arthrodia, I I'.t'i
setaceum, Closterium, I 190

— var. intermedium, 1 180
setigerum, Staurastrum, V 52
sexangulare, Cosmarium. 1 1 L 81

- f. minima, 111 82
Didymocladon, V 194

- Staurastrum, V 194

- var. Bupenramerarium, V 195
sexangularis, I'rsinella. Ill 81
sexcostatum, Didymidium (Stauras-

truni), V 147

— Pleurenteriuin (Staurastrum), V

147

— .Staurastrum, V 147

- var. product um, \" 148

— Staurastruui (Pleurenterium), A'

147

- Stephanoxanthium, V 147
sexnotatum, Cosmarium, 111 227

\ar. tristriatum. Ill 228
Sexual reproduction, I 9
sibiricum, Staurastrum, IV 152

- f. trigona, IV 153
sigmoideum, Closterium, 1 153

- f. major, I 153
silesiacum, Staurastrum, V GO
Sili(|ua. Closterium, I 154
Simii, Cosmarium, III 134
similatum, Cosmarium, L\' 10
Simonyi, .Staurastrum, V 45, M>
sinensc, .Staurastrum, IV 170

— var. hibernicum, IV 175
sinostegos, Cosmarium, III 79

var. obtusius, III 79
I'l-sinclla, III 79
sinuata, Heterocarpella; II 12

.Mirrasterias, II 12
sinuosa, Helierella, II 2<>
sinuosum, Cosmarium, II 12; 111 44

var. decedens. 1 1 1 43
Dysphmctium, III 44
Euastrum, II 20

- var. reduction, 11 22

- var. simplex, II 22

MI -\vdrumeiise, Cosmarium, III 171
Smithii, Xanthidiuin, IV 61

— var. collum, IV 63

— var. major, IV 62

- var. variabile, IV 81
Smolandica, Ursinella, II 134

Smolandicum, Cosmarium, II 134

- var. angustatum, II 135
>Sno«doiiense, Euastrum, II 45
.Sol Euastrum, II 95

Helierella, II 95

- Micrasterias, II 95

var. brachyptera. 1 1 101
- f. glabmiseula, II 102

- var. ornata, II 97
solida. rrsinella, III 17»»
solidum, Cosmarium, III 170
sparsipUD/etatum, Dysphiiictium, 1 93
Specihc determination of Desmids,

I 18

speciosissimum, Cosmarium, III 254
s[)et.-iosum, Closterium, 1 119

- Cosmarium, 111 247 ; V 209

var. biforme, 1 11 249

- f. genuina. 111 24S
var. inilatum. 111 253
\ar. Rostafinskiij III 251
var. simplex, III 250

Dysphiiictium, 111 248
Kuastrum (Cosmarium), III 248
-|>rctal)ilc. Cosmarium, II I 130

Kuastrum (Cosmarium), HE 130
sph;rrirum, Cosmarium, 111 151
sphseroid6um, C'osmarium, 111 178 ;

IV 3( i

S))li;.To/.osma, 12: \' 206
sphagnicolum, Cosmarium, 1 1 1 71
sphalerostidia. I'rsinella, III I7»i
-|)halerosticliuiii, Cosmarium, 111.176
spiniferum, Staurastrum, V 50
spinospermum, Penium, I 78

- f. minor, I 78

spinosporum, Cosmarium, IV 25
spinosurn, Did vmidium (.Stauras-
trum), V 174

Euastrum, II 38

- Staurastrum, V 173
spinulosum, Phycastrum, \' 23

- Sphserozosma, A' 213

— Xanthidiuin, IV (54
spiraliferum, Closterium, I 88
Spirotamia, 1 1, 3, 24, 25. 37
spirotsenia, Genieularia, 1 36

- Gonatozygon, I 30
SpirotaenieaB, I; 25, 37
spirostriolatum, Penium, I 24, 88

- var. amplification. I 88
>S])ondylosium, I 2 ; V 219
spongiosa, Binatella, V 70
spongiosum, Didymidium (Stauras-

trum),V'77

— Staurastrum, \' 76

var. cunibri'-um. \' 79

var. Grifiithsianum, V 78, 187

296

INDEX.

spongiosum, Staurastrum, var. per-

bifidum, V 78
Sportella, Cosmarium, III 185

- var. Corbula, III 183

— var. subnudum, III 186

- Ursinella, III 185
Staurastrum, I 2, 3, 24, 28 ; IV 118

- Micrasterias, V 101
Stella, Didymocladon, V 194

- Staurastrum, V 194
stellinum, Cosmarium, II 102
strangulatum, Dysphiiictium, III 29
strangulatus, Calocylindrus, III 29
stratum, Oocardium, V 204

— var. minor, V 205
Strensallense, Staurastrum, V 196
Streptonema, I 25, 28

striata, Ursinella, III 223
striatum, Cosmarium, III 223
strigosa, Arthrodia, I 165
strigosum, Closterium, I 165

- var. typicum, I 165
striolata, Arthrodia, I 123
striolatum, Closterium, I 122

- var. a, I 122

- var. costatum, I 121

- var. elongatum, I 125

- var. orthonotum, I 123, 124

- f. recta, I 124

- var. tumidum, I 123

- var. typicum, I 123

- var. Ulna, I 127
Pliycastrum (Amblyactinium),

IV 177

- Staurastrum, IV 177

- f. brasiliensis, IV 177

— var. divergens, IV 178

- var. celandicum, IV 177
subalatum, Cosmarium, III 255
subarctoum, Cosmarium, III 31

- f. punctata, III 32
subarcuatum, Staurastrum, V 41
subaversum, Cosmarium, II 174
subavicula, Staurastrum, V 175, 181
Subbotrytis, Cosmarium, IV 5
Subbroomei, Cosmarium, IV 23
subcapitulum. Cosmarium, III 73
subcirculare, Cosmarium, II 138

- var. rugosum, II 139
subcontractum, Cosmarium, II 174
subcostata, Ursinella, III 236
subcostatum. Cosmarium. Ill 236

- var. Bceckii, III 238

- f. minor, III 238
subcrenata, Ursinella, III 229
subcrenatum, Cosmarium, III 228

- var. divaricatum, III 230, 238
subcruciatum, Staurastrum, V 42

Subcucuniis, Cosmarium, II 155
subcylindricum, Cosmarium, IV 44
subdanicum, Cosmarium, 111 122
subdirectum, Closterium, I 125
subexcavatum, Cosmarium, III 148

• var. ordinatum, III, 149
subgracillimum, Staurastrum, V 118
subhastiferuni, Xanthidium, IV 56

— var. Murrayi, IV 57
subjuncidum, Closterium, I 125
sublsevispinum, Stuarastrum, V 91
sublatum, Cosmarium, IV 21
sublobata, Ursinella, II 73
sublobatum, Cosmarium, II 73

— Euastrum, II 73

• var. crispulum, II 72

— var. dissimile, II 74

— var. subdissimile, II 74
subnotabile, Cosmarium, III 263
subnotabilis, Ursinella, III 263
subnudibrachiatum, Staurastrum, V

91

subochthodes, Cosmarium, III 6 ; IV 6
suboctangulare, Penium, I 81
suborbiculare, Cosmarium, III 173

- Staurastrum, IV 159
suborbicularis, Ursinella, III 174
subortogonum, Cosmarium, III 86
subpalangula, Cosmarium, III 109

Dysphiiictium, III 109
subpronum, Closterium, I 175

• var. lacustre, I 176
subprotumida, Ursinella, III 231
subprotumidum, Cosmarium, III 231

• var. Gregorii, III 232
subpunctulatum, Cosmarium, III 209

- Staurastrum, IV 182
subpygmaBiim, Staurastrum, IV 162

• var. subangulatum, IV 163
subquadrans, Cosmarium, II 178
subquadrata, Ursinella, III 57
subquadratum, Cosmarium, III 57
subramosum, Cosmocladium, V 201
subrectum, Closterium, I 117
subrefractum, Staurastrum, V 86
Subreinschii, Cosmarium, II 58
subreniforme, Cosmarium, III 243
subreniformis, Ursinella, III 243
subretusiforme, Cosmarium, II 180
subscabrum, Staurastrum, V 82

• f. scabrior, V 83
subspeciosa, Ursinella, III 252
subspeciosum, Cosmarium, III 252

• var. effigiatum. III 253

• var. validius, III 253
substriatum, Cosmarium, III 224
Subtholiforme, Cosmarium, var. IMalin

vernianuin, III 199

INDEX.

297

subtholiforme, Cosmnrium, var. ver-

rucosum, III 203
subtile, Cosmarium. V 267
Dysphinctium, V 267

- Closterium, I 101
Penium, 192 ; V261, 267

- Staurastrum, V 134
subtrinodulum, Cosmarium, 111 218
subtruncatum, Penium, I >5
subtumida, Ursinella. II 102
Mil.tumidum, Cosmarium, II 192

var. Klebsii, 1 1 193
subtunrida, Pleurotaeniopsis, f. minoi-.

Ill 117
subturgidum, Cosmarium, HI 116

- f. minor, 111 117
Dysphinctium, III 1 hi

subulata. Fnistulia. 1 17'.»

Stamoct'ras, 1 1 T'.l
subulatum, Closterium, I 179
subulatiis, Ai throdesmus, I \' 109

- t. americana, I\' 110

- f. media, IV 110

var. subequalis, IV 110
subundulata, Ursinella, II 151
subuiidulatinn, ( 'osmarium. II 151
surrisuni, Cosmarium, II 179
supraspecioBum, Co>inai-ium. var.

emarginatum, III 144
S \\arl/ii. Desmidium, I <» : V 242, 246

- var. amblyodon, V 212. 249
var. guadrangulatum, V 248

Diatorna, V 24(1
synthh'bomehum, Cosmarium, III 180

tatrica, Ursinella, III 45
tatricum, Cosmarium, III 45

- var. novizelandicum, III 46

- var. sphaemliferum, III 47
laxichondra, [Trsinella, IV 45
taxichondriforme, Cosmarium, II 136
taxiohoiidrum, (.'osmarium, IV 45

var. genuina, IV 45
teliferum, Staurastrum, V 58

- var. convexum, V 53, »><)

- f. obtusa, V 60
tenerrima, Spirota?nia, I 47
tenerrimum, Closterium, I 177
tenue, Closterium, I 157
tenue, Cosmarium, II 167
tenuissimum, Xanthidium, IV 110
tenuissimus, Arthrodesmus, IV 88,

116

— f. longispina, IV 116
terebrans, Staurastrum, V 156
Tetmemorus, I 3, 27, 216
Tetracanthum, IV 89
tetracentrotum, Xanthidium, IV 58

tetracentrotum, Xanthidium, f. pro-
tuberans, 1\' 59

• var. quadricornutum, IV 59
tetracera, Binatella, V 118

- Mirrasterias, V 118
tetracerum, Staurastrum, V 118, 123

• var. evolutum, V 107

• f. tetragona, V 120

• f. trigona, V 120

var. undulatum, V 119

var. validum, V 121
tetrachondra, Tisinella, II 175
tetrachondrum, Cosmarium, II 175
telra.iroiia, rrsiuella. Ill 17
ti-trai:onum, Cosmarium, III 17

• \ ar. I Javidsonii. 1 1 1 20
var. elogans. Ill 20

var. heterocrenatum, 111 19
var. Lundrllii. 1 1 1 18
var. ]iumilum, 111 40
Kiiastnim (('osmarium). III 17
Sp..ndylu.siiun, V 224, 226
tetraophthalma, ri^indla, 111271
tetraophthalmum, Cosmai-ium, III
270

var. I)c Xotarisii, III 124
var. Lundellii, III 271

• var. subrotundatum, III 273

- < 'osmarium. III 124
Didymidium (Cosmarium), III

271

Kuastnim. Ill 27::
Heterocarprlla, III 273
Thomasiana, llelierella, II 110

- .Mid'asterias, II 110

• f. major, II 112
Thwaitesii, ( 'alocyliiidrus, III 104

- ( 'osmarium, III 104

• var. curtum, I 07

• var. ma jus. III 62
var. penioides, III 105

• var. scoticum, I 96

• var. typicum, III 104

— Dysphinctium, III 104
IN 'iiium, I 87

Tigurinum, Didymidium (Stauras-
trum), V 39

tincta, Ursinella, II 168
tinctum, Cosmarium, II 168

— var. intermedium, II 169

• var. succisum, II 179

- Sphserozosma, II 168
Tohopekaligense, Staurastrum, IV

119; V178

— var. trifurcatum, V 179
tortum, Cosmarium, IV 161

— Staurastrum, IV 119, 161
toxon, Closterium, I 160

298

INDEX.

toxon, Closterium, var. valirlum, V

263

Trabocula, Closterium, I 205, 209
Docidium, I 210

- var. clavatum, I 211
Pleurotaenium, I 14, 209

- f. clavata, I 211

- f. granulata, I 211

- var. rectissimum, I 212

- var. rectum, I 212
trabeculata, Spirotsenia, I 45
trachydermum, Cosmarium, TIT 178
trachygonum, Staurastrum, V 50
trachynotum, Staurastrum, V 196

- var. annulatum, V 196
trachypleura, Ursinella, III 172
trachypleurum, Cosmarium, III 172

- var. genuinum, III 172

- var. minus, III 173

- var. verrucosum, III 203
trachytithophomm, Staurastrum, IV

165

Trafalgarica, Ursinella, II 161
Trafalgaricum, Cosmarium, II 162
trapezieum, Staurastrum, var. cam-

pylospinosum, V 69
Traunsteineri, Staurastrum, V 169
triangularis, Arthrodesmus, IV 97

- var. americanus, IV 110

- var. hebridarum, IV 100

- var. inflatus, IV 99

- var. subtriangularis, IV 100

- f. triquetra, IV 89, 100

- f. triquetra, IV 99
tricorne, Phycastrum, V 138

- (Pachyactinium), V 138

— Staurastrum, IV 170; V 112;
138, 139

- var. /5, V 111

- var. semicirculare, V 139
tricornis, Binatella, V 138
tricrenatum, Cosmarium, IV 37
tricuspidata, Binatella, V 23
tridens, Phycastrum, V 101
tridentulum, Docidium, I 208

Penium, I 208
Pleurotsenium, I 208

- var. capitatum, I 209

- var. granulatum, I 209
trilobatum, Phycastrum, IV 170

- Streptonema, V 245
trilobulata, Ursinella, II 185
trilobulatum, Cosmarium, II 185

Didymidium (Cosmarium), II

185

trilobum, Staurastrum, IV 133
Triploceras, I 25, 27
trispinatus, Arthrodesmus, IV 115

Trelleckense, Staurastrum, V 70
Treubii, Spondylosium, V 226
trochiscosporum, Closterium. I 137
tnmcata, Helierella, II 83

- .Micrasterias, II 82

- forma c, II 85

- var. Bahusiensis, II 85

- var. euastroides, II 83

- f. granulata, II 85

- f. punctata, II 73

- var. quadragies-cuspidata, II
83

- var. quadrata, II 83

- subsp. radiosa, II 84

- var. semiradiata, II 84

- var. tridentata, II 83, 84

- Spirotsenia, I 40
truncatella, Ursinella, III 72
truncatellum, Cosmarium, III 72

Euastrum (Cosmarium), III 72
truncatum, Closterium, I 203

- Cosmarium, II 82
Didymidium (Micrasterias), f.

crenatum, II 85

- f. dentatum, II 83

— Docidium, I 203
— • Mesota?nium, I 54

— Penium, I 82

- f. punctata, I 82
Pleurotsenium, 1 203

- var. crassum, I 204

- var Farquharsonii, I 205

- var. granulatum, I 205
tuberculatum, Dysphinctium, IV 42

- Cosmarium, IV 42

- Staurastrum, V 148
tuberculatus, Calocylindrus, IV 42
tumens. Cosmarium, III 264

Dysphinctium, III 264
tumida, Binatella, IV 142

- Temperea, IV 142
Ursinella, II 160

tumidum, Closterium, I 156

- var. sphaerospora, V 263

- Cosmarium, II 160

— f. subrectangularis, II 161
Phycastrum, IV 142
Pleurenterium, IV 140

- Staurastrum, IV 140
timguscaiium, Staurastrum, V 28
turfosa, Spirotsenia, I 42
turgescens, Staurastrum, IV 167

- var. arcticum, IV 169
turgida, Arthrodia, I 171
turgidulum, Closterium, I 121
turgidum, Closterium, I 170

- var. decoratum, I 172
subsp. giganteum, I 171

INDEX.

299

turgidum, Cosmaridium, III 115
- Cosmarium, III 115

var. subrotundatum, III 116
Docidium, III 115
Dysphinctium. Ill 115
Pleurotaenium, III 115
turgidus, Caloeylindrus. Ill 115

PJeurotaeniopsis, III 115
Turner!, Cosmarium, 111 160
Turnerianum, Cosmarium, II 145
Turnerii, Euastrum, II 37
Turpinii, Cosmarium, III 189

var. Brebissonii. III Is'.t
var. cambrirum. IV 4S
var. eximium, III 192
f. gallica, III 189
- var. Lundfllii. Ill ls««
var. podolicum, III 191
var. polonicum. III 182
frsinella, III ls«.i

, Closterium, I 127
umbilicatum, Cosmarium, 1 1 1 88

undulata. H \ a]<-t hcca, V 239
var. producta, \ 23*. >
rrsinella, II 14S

undulatum, Cosmarium, II 148
var. crenulatum. II 150
var. minutum. II 149
\ar. nbtusatum. III 7
\ ar. subundulatum, II 151

- var. tumidum, II 151
var. Wollei, II 150

Didymidium (Cosmarium), II I -is
Docidium, I 14. 194

var. dilatatum, I 196

- f. perundulata, I 196
Euastrum (Cosmarium), II 14S
I'lfUi-otii-nium. I 195

Ungeriana, Ursinella, III 195
Ungerianum, Cosmarium, 111 195

var. subtriplicatum, III 196
Kiiastrum (Cosmarium), III 1(.>5
Timeri, Didymidium, V 28

- Staurastrum. V 28
unidentata. Sphserozosma, V 2<><)
tYsinella, II 126

Vacuoles, I 5

validum, Euastrum, II 75

variabile, Xanthidium, IV 81

- var. complexum. IV 83
variabilis, ActinocA'dus, V 235
Variation, I 7

variolata, Ursiuella, II 203
variolatum, Cosmarium, II 203
vastum, Staurastrum, V 181
Vegetative reproduction, I 8

ventricosa, Helierella, 11 4
ventricosum. Euastrum, II 4
Venus, Arthrodia, I 137

- Closterium, 1 137
venusta, Ursinella, III 9
venustum, Cosmarium, III 8

— var. hypohexagonum, III 10

- f, incrassata. Ill 10
var. majus. 1 1 1 11

f. minor. III 10
Euastrum, III 8 ; V 269

var. majus. Ill 11
vrrrurosa. Helierella, II 64

]\Ii( rast( lias, 1 I 109
verrueosum. Kuastrum, 11 2. 64
var. alatum, II 67

- var. coarctatum, 1 1 66

\ ar. plain toiiicum, 1 1 67

- var. roductum, II 65
var. sim])lcx. II <i~

- f. tuiiit'M -ens. 1 1 Ii7
var. t\|>icuni. 1 1 Ii4

vrrtobrata. Istliniia. \" L'li'.l

- IstliniMsim. \" iMKI
vertebratum. Desmidium, \" 2<>(.t

- Sphaerozosma, \' 209

var. latins. \* 211

- f. minor. V 210, 213

\ ar. pimrtulatum, A" 210
vertioillatum, Staurastnnn, I 14 : V

155, 156
vestitum, Didymidium (Staurastrum),

V 158

— Staurastrnm, \' 158

var. diplacanthum, V 186
var. ornatum, V 158
var. semi vestitum, V 160
var. subanatinum, \" 159

vexatum. Cosmarium, III 187
var. concavum, III 187

violascens. Mesota-nium, I 6, 55

— Palmogloea, I 55
viride, Cosmarium, III 113

- f. glabra, III 114

- f. minor. III 113
Dysphinctium, III 113

viridis. Colpopelta, III 113
Volkensii. Pleurotaeniopsis, III 22

Wallichii, Helierella, IT 122
Micrasterias, II 122

var. Hermanniana, II 122

- f. major, II 122

- f. typica, II 122

- Sphserozosma. V 214

- var. anglicum, V 215
Webbianum, Euastrum. II 34

300

INDEX.

Westianum, Cosmarium, III 135

— Xanthidium, IV 81
Westii, Staurastrum, V 187
Willeanum, Cosmarium, III 148
Willei, Dysphinctiuni, III 148
Wittrockii, Cosmarium, III 179

var. Schmidlei, III 179

— Ursinella, III 179

Wrightianum, Cosmarium, III 127
Xanthidium, I 4, 27 ; IV 48

zonatum. Cosmarium, III 123

— Dysphinctium, III 123
Zoos pores, I 9
Zygospores, I 10, 11

ADLARD AND SON AND WEST NEWMAN, LTD., LONDON AND DORKING.

EXPLANATIONS OF Till-, PLATES.

EXPLANATION OF THE LETTERING.

a, a', a''. Front view of cell or seimceil.
6, bf. Vertical view.

c. Side view.

d. Basal view of semicell.

[The asterisk * denotes that the figure so marked is original by
the Author, and is not from the pencil of Professor West.]

Plate 129

PLATE CXXIX.

FIGS. PAGE

1*. — Staurastrum disputatum W. & G. S. West, forma
minor, X 630. [ Consult vol. iv,p. 176, PL CXXVI,
fig. 16.]
2-6.— St. glabrum (Ehr.) Ealfs. 2 and 3, X 520; 4 and

5, larger forms, X 520 . . .2

6-8.— St. apiculatum Breb. 6 X 520 ; 7*, X 510 ; 8,

zygospore, X 520 . . .6

9-12.— £Z. dejectum Breb. 9 and 10, X 520 ; 11, form
with parallel spines, X 520 ; 12, zygospore, X
720 (after Beinseh) . . .7

13. — St. dejectum forma major W. & G. S. W. X 520 . 9
14-15. — St. Dickiei Ralfs. 14, X 520 ; 15, zygospore,

X 356 . . . .3

16. — St. Dickiei var. circidare Turn. X 520 . 5

17. — St. Dickiei var. rhomboideum W. & G. S. W.

X 520 5

PLATE CXXIX.

G.S.W. & K.C del.

Huth, London.

Plate 130

PLATE CXXX.

FIGS. PAGE

1-2. — Staurastrum dejectum var. patens Nordst. 1, X 570

(after Nordstedt) ; 2, X ? (after Borge) . 9

3-5. — St. dejectum var. inflatum West. X 520 . 10

6-8. — St. connatum (Lund.) Roy & Biss. 6, X 400

(after Lundell) ; 7, X 400; 8*, X 510 . 15

9. — St. connatum var. Spencerianum Nordst. Zygo-

spore, X 400 (after Nordstedt) . . 16

10-12. — St. mucronatum Ralfs. 10, zygospore, X 400

(after Ralfs) ; 11 and 12, x 520 . .11

13-14. — St. mucronatum var. subtriangulare W. & G. S. W.

X 520. . . . .12

15-16.— ££. curvatum West. 15, X 520 ; 16, X 400 . 19
17-18. — St. jacidifcrum West. 17, biradiate form, X 520 :

18, triradiate form, X 520 . .16

PLATE CXXX

G.S.W. & N.C.del

Hntt, London.

Plate 131

PLATE CXXXI.

FIGS. PAGE

1-3. — Staurastrum jaculiferum West. 1, quadrangular

form, X 520 ; 2 and 3, triangular forms, X 520 16
4-5. — St. jaculiferum var. excavatum W. & G. S. W. 4,

X 520 ; 5, biradiate form, X 520 . . 18

6. — St. jaculiferum var. subexcavatum W. & G. S. W.

X 430 . . . .18

7-8. — St. megacantlium Lund. X 520 . . 20

9-10. — St. megacanfhum var. scoticum W. & G. S. W.

X 520 21

PLATE OXXXI

G.S.W.&: N.C. del.

Huth,London.

Plate 132

PLATE CXXXII.

FIGS. PAGE

1-4. — Staurastrum pterosporum Lund. 1 and 2, x 500 ;
3, zygospore, X 400 (after Lundell) ; 4, zygo-
spore of biradiate form, X 600 (from a drawing
by Dr. J. Lutkemiiller) . . .14

5-8.— St.'O'Mearii Arch. 5 and 6, X ? (after Archer) ;

7 and 8, X 500 . . . .13

9. — $. O'Mearii var. minutum West. X 500 . 14

10-11. — $. aristiferum Ralfs. X 500 . . 22

12. — $. aristiferum var. protuberans W. & G. S. W.

X 520 . . . . 23

13-15.—$. cuspidattim Breb. 13* and 14*, x 510 ; 15*,

zygospore, X 510 . . .23

16-17. — $. cuspidatum var. divergens Nordst. 16, X 400 ;

17, zygospore, X 400 . . .25

18-19.—$. Gitspidatum var. maximum West. X 520 . 24

20.—$. leptodermum Lund. X 400 (after Lundell) . 27

PLATE CXXXII.

G.S.W. &N. C. del.

Huth London.

Plate 133

PLATE CXXXIII.

FIGS. PAGE

1. — Staurastrum cuspidatum var. coronulatum Gutw.

X ? (after Gutwinski) . . .26

2-3. — St. pseudocuspidatum Roy & Biss. 2, x 520 ;

3, X 400 . . . .26

4. — St. tunguscanum Boldt. X 400 (after Boldt) . 28
5. — St. Ungeri Reinsch. X 500 (after Reinsch) . 28
6-7.— St. mbcruciatum Cooke & Wills. 6*, x 510 ;

7, X 500 . . . .42

8-10.— St. Avicula Breb. 8, X 520 ; 9*, X 510 : 10*,

forma, X 510 . . . .40

11*. — St. Avicula var. subarciiatum West. X 510 . 41
12. — St. Avicula Breb. forma. Zygospore, X 400 (after

Roy & Biss.) . . . .40

13-14. — St. denticulatutn (Nag.) Arch. 13, x 520 ; 14, X

500 . . . . .38

15. — ? St. denticulatum. Zygospore, X 520 (from an

unnamed drawing by Professor West) . 39

16. — St. corntitum Arch. X 600 (after Roy & Biss.) . 31
17-19.— St. lunatum Rails. 17 and 18 x 400 ; 19, X 520 29
20-22. — St. lunatum var. planctonicww. 20, X 500 ; 21

and 22, X 520 . . . . 30

PLATE CXXXIII

G.S.W. & N.C. del.

Huth, London.

Plate 134

PLATE CXXXIV.

FIGS. PAGE

1*. — Staumstrum longispinum (Bail.) Arch, x 510 . 33

2-3. — St. longispinum var. bidentatum (Wittr.) W. &

G. S. W. 2*, x 510 ; 3, X ? . 34

4:.— St. bifidum (Ehr.) Breb. X 520 32

5. — St. quadrangulare Breb. X 520 . 37

6*. — St. adculiferum West. X 510 171

7. — St. spiniferum West. X 400 . 50

PLATE C XXXIV.

G S.W.&N.C.del.

Hirth, London.

Plate 135

PLATE CXXXV.

FIOS. PAGE

1-4. — Staurastrnm Simonyi Heimerl. 1-3, X 520 ; 4,

X 600. .' . . .45

5-7. — St. quadrispinatum Turn. X 520 . . 38

8-10.— St. pungens Breb. x 520 . . .44

11. — >Sft. Brasiliense Nordst. X 400 (after Nordstedt) 35
12-13. — St. Brasiliense var. Lundellii West. 12, x 520 ;
13, x 440 (slightly modified from a drawing by
Dr. Liitkemiiller) . . . 35

14-15.— St. Gatniense W. & G. S. West. X 520 32

PLATE CXXXV.

Jfutr.

Plate 136

PLATE CXXXVI.

FIGS. PAGE

1 . — Staurastrum Hystrix Ralfs. X 520 . . 60
2-6.— St. teliferum Ralfs. 2*, X 510 ; 3, X 520 ; 4, X
400 ; 5*, X 510 ; 6, zygospore formed by con-
jugation of 3 individuals, x 400 . . 58
7. — St. teliferum forma obtusa West. X 400 . 60
8-10.— St. polytrichum Perty. 8, X 520; 9, X 400;

10*, X 510 . . .53
11. — St. polytriclmm var. readingense Cushman. Zygo-
spore, X 450 (after Cushman) . . 54
12.— St. erostellum W. & G. S. W. X 660 . . 72
13-14. -St. setigerum Cleve. X 500 . . 52

PLATE CXXXVI.

G.S W. &N.C. del.

Hirih, London.

Plate 137

PLATE CXXXVII.

FIGS. PAGE

1-2. — Staurastrum gladiosum Turn. 1, X 400 ; 2, X

520 . . . . . 57

3. — St. gladiosum var. delwatulum W. & G. S. W. X

520 . . . . .58

4-5. — St. Brebissonii Arch. 4, X 600 (from a drawing by
Dr. Lutkemuller) ; 5, zygospore, X 720 (after
Cleve) . . . .61

6. — St. Brebissonii var. brevispinum West. X 400 . 63
7. — St. Saxonicum Bulnh. X 400 (after Roy & Biss.) 54
8.— St. Picum W. & G. S. W. X 520 . .51

9-11.— St. erasum Breb. 9, X 430 ; 10 and 11, X 520 . 71
12. — St. echinatum Breb. X 600 (from a drawing by Dr.
Lutkemuller from de Brebisson's original exsic-
cata) . . . . .56

13-14. — St. cumbricum West. X 400 . . 55

15-16. — St. cumbricum var. cambricum West. 15, X 400 ;

16, forma minor, X 400 . . .56

PLATE GXXXVII.

C.S.W. & N.C. del.

Huth, London.

Plate 138

PLATE CXXXVIII.

FIGS. PAGE

1-3. — Staurastrum pilosum (Nag.) Arch. 1, X 520
(vertical view in outline only) ; 2, zygospore,
X 400 (after Wittrock), cf. footnote, p. 64 ;
3*, X 510 . . .63

4-6.— St. hirsutum Breb. 4, X 500 ; 5, X 460 ; 6, forma
minor, zygospore, X 550 (from a drawing by Dr.
Liitkemiiller) .... 65

1-8.— St. Ravenelii Wood. 7, X ? (after Turner) ; 8*,
forma X 810 (from Wittr. & Nordst. 'Alg. Exs.'
no. 1477) . . . 70

9. — St. muricatum Breb. X 520 . . .67

10-12. — St.pyramidatumWest. 10, vertical view, X 520;

11 and 12. X 520 . . . 68

13. — St. pyramidatum var. coilon West. X 400 (outline

only) . . . . .69

PLATE GXXXV

/^* \

&\VXv-'-///J

X> __^

G.S.W. &N.C.del

h, L on d

Plate 139

PLATE CXXXIX.

FIGS. PAGE

1-2. — Staurastrum muricatum Breb. 1, X 520 ; 2*, X

520 . . . . .67

3. — St. tmchygonum West. X 400 . . 50

4. — St. horametrum Roy & Biss. x 400 (after Roy

& Biss.) . . . .51

5. — St. cristatum Nag. X 520 . . .47

6. — St. oligacantkum Breb. X 570 (after Nordstedt) 48

7. — St. oligacantkum var. incisum West. X 400 . 49

8-9. — St. echinodermum W. & G. S. West. 8, X 520 ;

9, vertical views, X 520 . . .79

10*. — St. maamense Arch. X 510. . . 75

11-14.— &. Arnellii Boldt. X 520 . . . 79

15. — St. Arnellii var. spinifetum W. & G. S. West. X

520 . . . . .80

16. — St. pyramidatmn West. Zygospore, X 520 . 68

PLATE CXXXIX.

G.S.W &N.C. del.

Huth, London.

Plate 140

PLATE CXL.

FIGS. PAGE

1-2. — Staurastrum scabrum Breb. X 520 . . 81

3-4. — St. subscabmm Nordst. 3, X 400 (after Nordstedt) ;

4. X 520 . • . .82

5. — St. subscabrum forma scabrior West. X 400 . 83
6-7. —St. acarides Nordst. 6*, X 510 ; 7, X 570 (after

Nordstedt) . . . .73

8-10. — St. acarides var. eboracensis West. 8*, X 510 ;
9, X 400 ( in outline only) ; 10, forma hexagona
in vertical view, X 400 (in outline only) . 74

11-13.— St. asperum Breb. 11*, X 510; 12 and 13, X 520 74
14*. — St. spongiosum Breb. X 510 . . 76

15. — -St. spongiosum, var. Griffithsianum (Nag.) Lagerli.

X 600 (after Nageli) . . .78

16*. — St. spongiosum var. perbifidum AVest. X 510 . 78

PLATE CXL.

G.S.W <S W.C. del.

Huth, London.

Plate 141

PLATE CXLI.

FIGS. PAGE

l-3.—Staurastrum Iceve Rails. 1*, X 510 ; 2, x 810 ;

3, zygospore, X 520 . . .92

4-7.— St. inconspicuum Nordst. 4, X 590 ; 5, X 400 ;
6, x 1000 ; 7, zygospore X 600 (after Liitke-
miiller) . . . .86

8.- — St. inconspicuum var. crassum Gay. X 520 . 87
9-10.— St. bacillare Breb. 9. X 400 ; 10, X 400 (after

Ralfs) . . . . .84

11-12. — St. bacillare var. obesum Lund. 11, X 400 (after

Lundell) ; 12, X 400 . .84

13. — St. bacillare var. undulatum var. nov. X 520 . 85
14-15. — St. brachiatum Ralfs. 14, X 520 ; 15. zygospore,

X 520 . . . ' .88

IQ.—St. nodosum W. & G. S. W. X 660 . . 88

17-18. — St. Icevispinum Biss. 17, X ? (after Bissett) ; 18,

a form, x 520 . . . .90

19. — St. sublcevispinum W. & G. S. W. X 520 (front
view too long in proportion, because cell-
division is just about to take place) . .91
20.— St. subnudibrachiatum W. & G. S. W. X 520 . 91
21. — St. asperum Breb. Zygospore, X 400 (after Ralfs) 74

PLATE CXLI.

G.S.W. & N.C. del.

Huth; London.

Plate 142

PLATE CXLII.

FIGS. PAGE

1-7. — Staurastrum brachiatum Ralfs. 1-6, x 520 ; 7,

zygospore, X 520 . . .88

8.- — St. inconspicuum Nordst. X 500 (after Borgeson) 86
9-10.— £*. fmnconicum Reinsch. 9, X 750 ; 10, x 625

(both after Reinsch) . . .85

11-14.— &. Jiexacerum (Ehr.) Wittr. 11, 12, and 13, X 520 ;

14, zygospore X 400 (after Ralfs) . . 138

15. — St. hexacerum var. semicirculare Wittr. X 400 (after

Wittrock) . . . .139

16-18.— iS^. neglectum G. S. West. 16, X 500 ; 17, X 840
(vertical view) ; 18, zygospore, X 400 (after
Ralfs) . . . . .111

19-20.— St. Haaboeliense Wille. 19, X 520 ; 20, X 500 . 140
21-22.— St. brachycerum Breb. 21, x 520 ; 22*. x 810 . 136
23.— S*. affine W. & G. S. W. X 520 . 128

24. — St. polymorphum Breb. Zygospore, X 600 (from

a drawing by Dr. Lutkemiiller) . . 125

PLATE CXLI1

G.S.W.& N.C. del.

Plate 143

PLATE CXLIII.

FIGS. PAGE

1-3. — Staurastrum polymorphum Breb. 1, x 520 ; 2*,

X 510 ; 3, X 840 . . .125

4*. — St. polymorphum var. pusillum West. X 510 . 127
5. — St. polymorphum var. simplex W. & G. S. W. X

400 '. . . . .128

6. — St. polymorphism var. munitum West. X 520 . 129

7-8— S*. inflexum Breb. 7, X 520 ; 8*, X 510 . 108

9-13.— ££. crenulatum (Nag.) Delp. X 520 . . 110

14-16. — St. proboscidium Perty. 14 and 15, forms, X 500

and 520 respectively ; 16, X 400 (after Ralfs) . 129
17.— St. bicorne Hauptfl. X 460 (after Haptfleiscuh) . 117
18-19.—^. oxyacanthum Arch. 18*, X 510 ; 19*, X 510 169
20-22. — St. oxyacanthum var. polyacanthum Norclst. 20*, X
510 ; 21*, basal view of semicell, X 510 ; 22*,
vertical view, x 510 . . ,170

23— St. eboracense Turn. X 500 137

PLATE CXLHI.

G.S.W. & N.C.dcl.

Huth , London.

Plate 144

PLATE CXL1V.

FIGS. PAGE

1-2. — Staurastrum subgracillimum W. & G. S. W. 1,
from Ireland, X 520 : 2, from the United States,
X 520. . . . .118

3-7 .— S* gracile Ralfs. 3*, X 510 ; 4, x 520 ; 5*, X
510 ; 6*, a form, X 510 (det. G. S. West) ; 7
zygospore, X 520 . . .96

8-9.— St. gracile var. nanum Wille. 8, X 400 9, X 520 100
10. — St. gracile var. coronulatum Boldt. X 520 . 100
11. — St. gracile var. tenuissima Boldt. X 500 (after

Boldt) . . . .100

12.— St. gracile var. cyathiforme W. & G. S. W. X 520. 99
13. — St. gracile var. bulbosum West. X 400 . 98

PLATE CXLIV.

10

G.S.W. &N.C. del.

Huth, London.

Plate 145

PLATE CXLV.

FIGS. PAGE

1-5. — Staurastrum paradoxum Meyen. 1, X 520 ; 2*,
X 510 ; 3 and 4; X 520 ; 5*, biradiate form, X
510 . . . . . 101

6. — St. paradoxum var. parvum West. X 520 . 100

7-8. — St. paradoxum var. evolutum West. X 520 . 107
9-10. — St. paradoxum var. cingulum W. & G. S. W. 9 X

384 ; 10, X 520 . . . . 105

11-12.— -S*. pseudopdagicum W. & G. S. W. X 520 . 107

PLATE CXLV.

Hu£h. London.

Plate 146

PLATE CXLVI.

FIGS. PAGE

1. — Staurastrum paradoxum var. nodulosum West. X

400 . . . . . 106
2-3. — St. paradoxum var. longipes Nordst. 2, X 520 ; 3,

forma major, X 520 . , .103

4:.— St. dubium West. X 400 . .112

5.— St. boreale W. & G. S. W. X 520 . 112

6.— St. pdagicum W. & G. S. W. X 520 . 124

7. — St. anatinum Cooke & Wills, x 520 . .142

8*. — St. anatinum var. (runcaium West, x 510 145

PLATE CXLVI.

C. del.

Lon

Plate 147

PLATE CXLVII.

FIGS. PAGE

1. — Staurastrum anatinum Cooke & Wills, small form,

X 520 . . . . 142

2. — St. anatinum var. biradiatum West. X 400 . 145

3. — St. anatinum var. pelagicum W. & G. S. W. X 520 140
4. — St. anatinum var. Lagerheimii (Schmidle) W. &

G. S. W. X 520 . . . 144
5. — St. anatinum var. longibrachiatum W. & G. S. W.

X 520 . . . . 146

6. — St. anatinum var. grande W. & G. S. W. X 520 . 144

7.— St natator West. X 400 149

PLATE C.XLVII.

G.S.W.&N.C.del.

Huth, London.

Plate 148

PLATE CXLVIII.

FIGS. PAGE

1*. — Staurastrum Duacense W. & G. S. W. X 510 . 116

2— St. Manfeldtii Delp. X 520 . .114

3. — St. Manfeldtii var. annidatum W. & G. S. W, X

520 . . . . . 115

4.— St. dorsidentifemm W. & G. S. AV. X 520 171

5-6— #*. Sebaldi Keinsch. 5*, X 510 ; 6, x 520 166

7*. — St. Sebcddi var. ornatu/m Nordst. X 510 167

PLATE CXLV11I.

G.S.W.&N.C.del.

h'uth, London.

Plate 149

PLATE CXLIX.

FIGS. PAGE

1. — Staurastrum iotanum Wo lie. X 520 . . 121

2-L— St. tetmcerum Rails. 2, x 520 ; 3*, X 550 ; 4*.,

forma trigona, X 510 . . .118

5. — St. tetracerum var. validum W. & G. S. W. X 520 121
Q.—St. micron West. X 625 . . 123

7.— St. irregulare West. X 520 . . . 150

8.— St. latiuscidum West. X 520 . . 124

9*.— ££. cyrtocerum Breb. X 510 . . . 135

10. — St. cyrtocerum var. compactum West. X 520 . 136
11.— St. pseudotetmcerum (Nordst.) West. X 520 . 122
12.— St. Chavesii Bohlin x 520 . . .134

13. — St. Pseudosebaldi var. simplicius West. X 520 . 114
14-15. — St. Heimerlianum Liitkem. 14, X 950 (vertical
view, X 850) ; 15, zygospore, X 850 (all from
drawings by Dr. Liitkemiiller) . .165

16. — St. Heimerlianum var. spinulosum Liitkem.

1000 (after Liitkemuller) . . . 165

17. — St. Sebaldi var. productum West. X 520 . 168

PLATE CXLIX.

i,?l.

Kuth,Lor ion.

Plate 150

PLATE CL.

FIGS. PAGE

1*. — Staurastrum Arachne Ralfs. X 510 . . 151

2. — St. Arachne var. curvatum W. & G. S. W. X 400 152

3. — St. Arachne var. arachnoides West. X 400 . 152
4. — St. cyrtocerum Breb. X 400 . . .135
5-9. — St. margaritaceum (Ehr.) Menegh. 5*, X 510 ;
6, X 500 ; 7, X 460 ; 8, zygospore, X 520 ;

9*, a form, X 510 . . . 131

10. — St. margaritaceum var. coronulatum West. X 400 132
11. — St. margaritaceum var. hirtum Nordst. X 400

(after Nordstedt) . . . 133
12. — St. margaritaceum var. subcontortum W. & G. S. W.

X 520 . . . . 134
13. — St. margaritaceum var. robustum W. & G. S. W.

X 520 . . . . 133

14. — St. sexcostatum Breb. X 460 . .147

15*.- — St. sexcostatum var. productum West. X 510 148

16*.— -£Z. Cerastes Lund. X 510 141

PLATE CL

\

Plate 151

PLATE CLI.

FIGS. PAGE

1. — Staurastrum Cerastes Lund. X 520 . .141

2-5. — St. elongatum Barker. 2 and 4, X 520 ; 3, ver-
tical view, X 520 ; 5, basal view of semicell, X
520 . . ' . . . 156

6.— St. barbaricum W. & G. S. W. X 520. . 157

7-8. — St. verticillatum Arch. 7, X 520 ; 8*, vertical

view, X 510 . . . .155

9-11. — St. vestitum Rail's. 9, x 500; 10, vertical view

X 500 ; 11, X 430 . . . 158

CLI

del

Hut/h, London.

Plate 152

PLATE CLII.

FIGS. PAGE

1-2. — Staurastrum Ophiura Lund. 1, X 520 ; 2*, x

510 . . . . . 153

3-4.' — St. Ophiura var. cambricum W. & Gr. S. W. 3, X

430 ; 4*, vertical view, X 510 . . 154

5-6. — St. vestitum Ealfs. 5, X 520 ; 6, zygospore, X 500

(after Wolle) . . .158

7-8. — St. vestitum. var. semivestitum West. X 520 160

PLAT£ CLII.

G.S.W.&N.Cdel.

Hu-ih .London

Plate 153

PLATE CLIII.

FIGS. PAGE

1-4. — Staurastrum aculeatum (Ehr.) Menegli. 1, X 520 ;
2, another form, X 520 ; 3, X 520 ; 4*, vertical
view, X 510 . . . .160

5. — St. vestitum var. subanatinum W. & G. S. W. x

520 . . . . . 159

6*-7*.—St. Archerii West, X 510 155

PLATE CLJII.

G.S.W. & jV.C. del

Huth, London.

Plate 154

PLATE CLIV.

FIGS. PAGE

1-4. — Staurastrum controversum Breb. 1, 2, and 3, x 520
(36 original) ; 4, zygospore, X 600 (after Liitke-
miiller) . . . .162

5-7. — St. cosmospinoxum Borg. 5, X 400 (after Roy &
Biss.) ; 6, X 390 (after Borgeson) ; 7, X ? (after
Borgeson) . . . .164

8*. — St. monticulosum Breb. X 510 . . 183

9. — St. monticulosum var. bifarium Nordst. Forma X

520 . . . . . 184

10. — St. monticulosum var. grcenlandicum Gronblad.

400 .... 185

11.— St. monticulosum Breb. ? ? X 520 (see p. 184) . 183
12.- — St. monticulosum var. pulchrum West. X 520 (see

p. 186) . . . .185

13. — St. megalonotum Nordst. X 570 (after Nordstedt) 182
14-16.— S*. fotjictilatttm Lund. 14, x 520 ; 15*, X 510 ;

16*, biradiate form, X 510. . . 187

PLATE CLIV.

-

-*:,*

-**

G.S.W & N.C. del.

Huth, London.

Plate 155

PLATE CLV.

FIGS. PAGE

1-4. — Staurastrum furcatum (Ehr.) Breb. 1, zygospore,

X 400 (after Ralfs) ; 2, X 400 ; 3 and 4, X 500 173
5-6. — St. furcatum var. candianum (Delp.) Cooke. 5, X

about 400 (after Cooke) ; 6, X ? (after Delponte) 175

7. — St. furcatum var. subsenarium West. X 520 . 175

8— St. arcuatum Nordst. X 400 (after Nordstedt) . 180

9. — St. arcuatum var. Guitanense West. X 400 . 180

10.— St. subavicula W. & G. S. W. X 520 . . 181

II.— St. amphidoxon W. & G. S. W. X 400. . 181

12.— St. Tohopekaligcnse AVolle. X 520 . 178

13-14. — St. Tohopekaligcnse var trifurcatum W. & G. S. W.

13* X 510 ; 14, X 520 . . 179

PLATE CLV.

G.S.W.& N.C.del.

Huth, L o n dori.

Plate 156

PLATE CLVI.

FIGS. PAGE

l.—Staurastrum diplacanthum De Not. X about 600

(after de Notaris) . . . 186

2. — St. diplacanthum var. anglicum Turn. X about 450

(after Turner) . . . 186 .

3.— St. senarium (Ehr.) Ealfs. X 513 . 171

4.— ££. Westii Turn. about 400 (after Turner) . 187
5. — St. gemelliparum Nordst. X 520 . .176

6— St. Clevei (Wittr.) Roy & Biss. x 520. . 177

7-8. — St. furcigerum T&ieb. 7*, X 510; 8, zygospore, X

520 . . . . .188

9. — St. furcigerum var. reductum \V. & GL S. W. X 520 192
10. — St. furcigerum forma armigem (Breb.) Nordst.

( 520 . . . . . 191

1 J . — St. furcigerum forma, x 520 . .188

PI

> <-

-^

Plate 157

PLATE CLVIL

FIGS. PAGE

1*. — Staurastrum furcigerum forma eustephana (Ehr.)

Nordst. X 510 . . . . 190

2-3.— -St. sexangulare (Bulnh.) Lund. 2*, X 510 ; 3,

X 520 . . . . 194

4. — St. sexangulare var. supernumcrarium W. & G. S.

W. X 520 .... 195

Q.—St. Arctiscon (Ehr.) Lund. X 520 . 193

PLATE CLVII.

G.S.W.& N.C. del.

Huth, London.

Plate 158

PLATE CLVIII.

FIOS. PAGE

1-3. — Cosmocladium constrictum Arch. 1, X 520 ; 2, x
1200, showing pores of cell-wall (after Liitke-
miiller) ; 3, zygospore, X 600 (after Roy £ Biss.) 198
4-7. — C. perissum Roy & Biss. 4, X 600 (after Roy &
Biss.) ; 5, X 1200, showing pores (after Liitke-
miiller) ; 6, zygospores, X 600 (after Roy &
Biss.) ; 7 zygospore, X 475 . . 200

8-10.— C. pusillum Hilse. 8 and 9, X 520 ; 10, X 950
(from a drawing by Dr. Liitkemuller from
' Rabenh. Alg. Eur.' no. 1963) . 201

11-12.— C.pukhellum'BiQb. 11, X 275 (after de Brebisson);

12, X 520 . . . 200

13-16.— C. Saxonicum De Bary. 13 and 14, X 500 ; 15, X
520 ; 16, X 1200, showing pores (after Liitke-
miiller) . . . 202

PLATE CLVni.

W * m

G.S.W. iN.C.del.

Huth, London.

Plate 159

PLATE CLIX.

FIGS.

Oocardium stratum Nag. 1*, natural size ; 2-6
(after Senn) ; 2, vertical section through cal-
careous tubes, X 400 ; 3, tubes seen from above,
X 650 ; 4-6, X 1000 ; 7, newly-divided indi-
viduals, X 800 ; 8, stained to show pores, X
1200 (7 and 8 after Lutkemiiller) . . 204

9-10. — Sphcerozosma vertebratum (Breb.) Ralfs. 9, X 520 ;

10, zygospores, X 400 (after Ralfs) . . 209

II— Sph. vertebratum var. latius W. & G. S. W. X 520 211
12. — Sph. vertebratum forma minor West. X 400 . 210
13*.— Sph. Aubertianum West. X 510 . 207

— Sph. Aubertianum var. Archeri (Gutw.) W. & G. S.
W. 14, x 520 ; 15, X ? (after Gutwinsld) ;
16*, X 510 ; 17, zygospores, X 520 . . 208

PLATE CLIX.

A

^(ffiSK^

G.S.W& JJ.C. del.

Plate 160

PLATE CLX.

FIGS. PAGE

1-3. — Sphcerozosma excavatum Ralfs. 1* and 2*, x 510 ;

3, zygospores, X 520 . . • .211

4-5. — Sph. excavatum var. subquadratum W. & G. S. W.

X 520 . . . . 212

6-7— jS^. granulatum Roy & Biss. 6, x 520 ; 7*, X 810 213
8. — Sph. granulatum var. trigranulatum W. & G. S. W.

X 520 . . . . 214

9. — Sph. Wallichii Jacobs. X about 400 (after Wal-

lich) . . . . .214

10-11. — Sph. Wallichii var. anglicum W. & G. S. W. 10, X

520 ; 11, X 830 . . . . 215

12*. — Sph. vertebratum var. punctulatum West. X 510. 210
13-14.— Onychonema filiforme (Ehr.) R. £ B. 13, X 400 ;

14*, x 510 . . . 216

15-16. — 0. Iceve Nordst. 15, X 520 ; 16, aplanospore ?,

X 520 . . . 218

17. — 0. Iceve var. micracanthum Nordst. Zygospore, x

500 . . . . . 219

18-19. — Spondylosium pygmceum (Cooke) West, x 400 . 220
20-21. — Sp. pygmceum var. monile (Turn.) W. & G. S. W.
20, X 450 ; 21, X ? (from a rough free-hand
drawing by Turner) . . .221

22. — Sp. pygmceum var. compressum West. X 400 . 221
23-25.— Sp. planum (Wolle) W. & G. S. W. 23 and 24, x

500 ; 25, x 1000 . 222

PLATE CLX.

G.S.W.&N.C.del.

Huth, London.

Plate 161

PLATE CLXI.

«

FIGS.

1-3. — Spondylosium pulchellum Arch. 1, X 400 ; 2, X

590 j 3, X 400 . . . . 227

4-5. — Sp. pulchellum var. pyramidatum West. 520 228
6-7.—% papiUoswn W. & G. S. W. 6, x 520 ; 7, X

400 . . . . . 223

8-11.—% secedens (De Bary) Arch. 8, X 830 ; 9, X
520 ; 10, X 830 ; 11, zygospores, X 600 (after
Liitkemuller) .... 225
12-14.—% tetragomtm West. 12 and 13, X 400 ; 14, X

1000 . . . . .226

15.—% ellipticum W. & G. S. W. X 520 . 222

16-27.— Hyalotheca dissiliens (Sm.) Breb. 16, X 520; 17*,
forma minor Delp. X 510 ; 18*, X 510 ; 19*,
vertical view of forma circidare, X 510 ; 20,
forma bidentida ; 21, forma tridmtula ; 22, 23,
24 and 25, formation of aplanospores, X 520 ;
26* and 27*, zygospores, X 510 . . 229

PLATE CLXI.

G.S.W.&N.C.del.

Huth, L on don.

Plate 162

PLATE CLXII.

FIGS. PAGE

l-l.—Hyalotheca mucosa (Mert.) Ehr. 1* and 2*, X 510 ;

3* and 4*, zygospores X 510 . . 235

5. — H. mucosa var. minor Roy & Biss. X 520 . 236
6-9.— #. undulata West. 6 and 7, X 400 ; 8, X 520 ;

9, showing pores, X 800 (after Liitkemuller) . 239
10.— H. Indica Turn. X 520 . . .237

11-15. — H. neglecta Racib. 11, 12, 13 and 14, formation
of aplanospores, X 520 ; 15, punctate membrane
ofaplanospore, X 520 . . . 238

16-18. — H. dissiliens var. hians Wolle. X 400. . 234

19. — //. dissiliens var. tatrica Racib. X 520 234

PLATE CLXII.

Plate 163

PLATE CLXIII.

FIGS PAGE

l-k.—Hyalotheca neglecta Kacib. 1, X 520 ; 2*, X 510 ;

3 and 4, zygospores, X 520 . . . 238

5-8. — Desmidium Swartzii Ag. 5* and 6*, X 510 ; 7*,

X 510 ; 8, zygospores X 416 ? (after Delponte) 246
9-10. — D. Swartzii var. quadrangulatum (Ralfs) Roy. 9*,

X 510 ; 10, X 346 (after Delponte) . . 248

PLATE CLXm.

G.S.W&N.C. del

Huth. London

Plate 164

PLATE CLXIV.

FIGS. PAGE

1-3. — Desmidiwn Aptogonum Breb. 1*, X 510 ; 2*,

vertical view, X 810 ; 3, zygospores, X 520 . 242
4-5.— D. Aptogonum var. Ekrenbergii Kiitz. X 520 . 243
6. — D. Aptogonum var. acutius Nordst. X 400 (after

Nordstedt) . . . .244

7-10. — D. ci/lindricum Grev. 7* X 510 ; 8*. vertical

i/

view, X 510 ; 9*, early stage in conjugation,
X 510 ; 10, ripe zygospore, X 520 . . 249

11, -D. occidentals AY. & G. S. W. X 400 . . 245

PLATE CLXIV.

G.SW. &-N.C. del.

Huth.london.

Plate 165

PLATE CLXV.

FIGS. PAGE

1-2. — Desmidium coarctatum Nordst. 1, X 400 (after

Nordstedt) ; 2, X 520 . . .252

3-4. — D. coarctatum var. cambricum West. X 400 . 252

5-6. — D. pseudostreptonema W. & G. S. W. 5, flattened

form, X 520 ; 6, trigonal form, X 520 . 244

7. — D. Swartzii var. amblyodon (Itz.) Rabenh. X 510. 249

8-9. — Gymnozyga moniliformis Ehr. 8*, X 510 ; 9, ver-
tical view, X 400 (after Ralfs) . . 255
10. — G. moniliformis var. gracilescens Nordst. Zygo-

spores, X 520 .... 256

PLATE C.LXV.

G.S.W. & N.C. del.

Huth, London

Plate 166

PLATE CLXVT.

FIGS. PAGE

1. — Staurastrum Chavesii Bohlin. x 000 (after Bohlin) 134
2*. — St. brevispinum Breb. Zygospore X 510 . 269

3—Euastrum laticolle West. X 500 . . 264

4.- — Staurastrum Pseudosebaldi Wille. X 480 (after

Wille) . . . . .113

5. — Desmidium gracileps (Nordst.) Lagerh. X 520

(5e, zygospore, x 400, after Lagerheim) . 253

6-7— D. quadratum Nordst. 6, X 520 (66, X 400, after
Nordstedt) ; 7, zygospore, x 400 (after Lager-
heim) .... 254
8-9.—Closterium tumidum Johns, var. spkcerospora

West. X 500 ; 8, vegetative cell ; 9, zygospore 263
10*. — Gymnozyga moniliformis var. gracilescens Nordst.

X 510. . . . .256

11-13.- — Eoya anglica West. 11 and 13, vegetative cells,

X 500 ; 12, zygospore, X 500 (all after Hodgetts) 259
14.- -R. cambrica West, forma limnetica West. X 500 260

PLATE CLXVI.

G.S.W. & N.C.del.

Huth,Iondon.

Plate 167

PLATE CLXVIT.

FTGS. PAGE

1-4. — Oocardium stratum Nag. var. minor Carter. 1*,
vegetative cell, X 510 ; 2*, 3* and 4*, stages in
conjugation, X 510 . . . 205

5. — Euastrum montanum West. Zygospore, X 600

(after Liitkemiiller) . . .265

6. — Roya obtusa (Breb.) West var. montana West.

Zygospore, X 510 (after Harris) . . 260

7. — ? Staurastmm inflexum Breb. Zygospore, x 600

(after Liitkemiiller ; see p. 109) . . 109

8*-9*.— St. Meriani Reinsch. Zygospores, X 550 . 269

10. — Spondylosium Lundellii Borge. var. triquetrum

(Lund.) nob. x 400 . . 225

11*. — Micrasterias papillifem Breb. Zygospore, X 435 266

PLATE CLXVII.

'• m

G.S.W.&N.C.del.

Huth, London.

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