OF THE THIRD TANGANYIKA EXPEDITION. 141 
fig. 4), but is distinguished by its narrower cells, its stouter and curved spines, 
and by the absence of pyrenoids from the chloroplast. 
It bears considerable resemblance to certain small and attenuated species of 
the genus Nitzschia. 
Genus CLOSTERILOPSIS, Lemm. 
164. CrosTERIOPSIS LONGISSIMA, Lemm. in Forschungsb. Biol. Stat. Plön, vii. 
(1899) p. 29, t. 2. figs. 30-38 ; W. у б. S. West, in Trans. Roy. Irish Acad. 
xxxiii. sect. В (1906), р. 106, t. 10. figs. 17-19. 
Nyasa.—Plankton, Deep Вау (24 June, 1904 ; no. 25) and off Karonga 
(1 July, 1904; no. 30). 
Victoria Nyanza.—Plankton, near Bukoba (18 Apr. 1905; no. 249). 
Genus SELENASTRU M, Reinsch. 
165. SELENASTRUM GRACILE, Reinsch, in Abh. Natur, Ges. Мн. iii. 
Heft 2 (1867), p. 65, t. 4. fig. 3. 
Diam. colon. usque ad 154 ш; crass. cell. 4-5 p. 
Tanganyika.—In swamp, Kituta (23 Aug. 1904; no. 72). 
Victoria Nyanza.—Plankton, near Bukoba (21 Apr. 1905; no. 232). 
Some of the colonies were of very large size. 
Genus KIRCHNERIELLA, Schmidle. 
166. KincHNERIELLA OBESA, (West) Schmidle, in Flora, lxxvii. (1894) 
р. 44.—Selenastrum obesum, West, in Journ. Roy. Mier, Soc. (1892) p. 734, 
t. 10. figs. 50-52. 
Tanganyika.—In swamp, Kituta (26 Aug. 1904 ; no. 50). 
Victoria Nyanza.—Plankton, near Bukoba (18 Apr. 1905 ; no. 252). 
Subfam. OocvsTIDE.. 
Genus OOCYSTIS, Ndg. 
167. OocvsrIs SOLITARIA, Wittr. in Wittr. $ Nordst. Alg. Елее, fasc. v. 
(1879) no. 244 ; Bot. Notiser (1879), р. 24. 
Nyasa.—In swamp, Karonga (2 July, 1904 ; no. 34). 
168. Oocystis PARVA, W. & G. S. West, in Journ. Bot. xxxvi. (1898); 
G. S. West, 1. с. xxxvii. (1899) t. 394. figs. 14-17. 
Nyasa.—Plankton, Monkey Вау (17 June, 1904 ; no. 15). 
169. Ooovsris LACUSTRIS, Chodat, т Bull. Herb. Boiss. у. (1897) р. 296 ; 
Algues Vertes de la Suisse (1902), p. 190. 
Long. colon. 39-54 p ; long. cell. 12-20 р; lat. cell. 7-13 р. 
Nyasa.—Plankton, Anchorage Bay (13 June, 1904 ; no. 9). 
