— 166 — 
35. . regulare Bréb. in Mém. Soc. Sciences, Cherbourg, 1856, IV, 
p. 304, t. II, f. 35. 
Forma apicibus crassioribus; striis validis, visis 11. 
Long. 240 yw; lat. 26,5; lat. apic. 8,5 p. 
With the preceding species. 
Area: Europe, W. Africa, India, Australia. 
36. ©. Ralfsii Bréb. in Ralfs Brit. Desm. 1848, p. 174, t. XXX, f. 2. 
Var. hybridum Rabenh. Krypt. Fl. Sachs. p. 174; Flor. Europ. Algar. 
Ill, p. 185. 
Long. 464 4; lat. 29,5; lat. apic. 6. 
Area: Europe, Ceylon and Singapore. 
37. . Kiitzingii Bréb. in Mém. Soc. Sciences, Cherbourg, 1856, IV, 
p. 156, t. II, f. 40. 
Long. 467—540 yw; lat 17 p. 
In stagnant water among Spirogyra decimina var. 
Area: Europe, N. America, Madagascar, India, Ceylon, Japan, New Zealand 
and Australia. 
38. 6. Cornu Ehrenb. 1830; Ralfs Brit. Desm. 1848, p. 176, t. XXX, 
f. 6 f et g. 
Var. siamense West & G.S. West, n. var. (Tab. nostr. II, fig. 6—7). 
Var. cellulis minus curvatis; zygospora subquadrata, angulis 
submamillatis. 
Long. 140-165; lat. 5,5—7,5; diam. zygosp. 23—25 p. 
This variety differs from typical Cl. Corne Ehrenb. in being somewhat 
less curved, and in the form of the zygospore, the angles of which are 
not so produced and do not project within the empty semicells. The 
zygospore is surrounded by a mucous investment and the semicells are 
attached to the outer edge of this mucus. 
In muddy ricefields. 
Area: Europe, N. and S. America. Australia. 
39, (€. tumidum Johnson in Bull. Torr. Botan. Club, vol. 22, no. 7, 
July 1895, p. 291, t. 293, f.4. C. Cornu var. @ Ralfs Brit. Desm. 1848, 
p. 176, t. XXX, f.6 a—e. C. Cornu et forma major Wille in Ofvers. af 
K. Vet.-Akad. Férh. 1879, no. 5, p. 59, t. XIV, f. 80, 81. 
a. Forma cellulis crassioribus. (Tab. nostr. II, fig. 4). 
Long. 125; lat. 18,5; lat. apic. 4y. : 
The form observed was proportionately a little thicker than Cl. tymidwm 
Johns., and the ventral margin was slightly less tumid. The relative in- 
crease in thickness was due to the somewhat greater curvature of the 
dorsal margin. The cell-wall was quite smooth and colourless and the 
apices were truncate exactly as in Johnson's figures. 
