156 MR. G. S. WEST ON THE FRESHWATER ALGJE 
The specimens observed had a rhomboidal central area (=forma biceps) : 
long. 60 ш; lat. ad med. 12 ш; lat. apic. 8'5 д. 
Nyasa.—In shore-pools, Nkata Bay (23 June, 1904 ; no. 22). 
221. NAVICULA ($ PrxNULARIA) MESOLEPTA, Ehrenb.; Kütz. Васі. р. 101 
(1844); И’. Sm. Brit. Diat. t. 19. fig. 182; Van Heurck, Synops. Diat. Belg. 
p. 79, t. 6. figs. 10, 11. 
Tanganyika.—In swamp, Тоа (10 Jan. 1905 ; no. 208). 
228. NaAvicULA ($ PINNULARIA) GIBBA, (Ehrenb.) W. Sm. Brit. Diat. i. 
t. 19. fig. 180. 
Nyasa.—In shore-pools, Nkata Вау (23 June, 1904 ; no. 22). In swamp, 
Kambwelagoon near Karonga (27 June, 1904 ; no. 20). 
Tanganyika.—In swamp, Mrumbi (27 Dee. 1904 ; nos. 195 and 196). In 
swamp, Toa (10 Jan. 1905 ; no. 208). 
229. NavicULA ($ PINNULARIA) ACROSPHÆRIA, (Bréb.) Kitz. Бае. (1844) 
p. 97, t. 5. fig. 2; W. Sm. Brit. Diat. t. 19. fig. 183. 
Nyasa.—In swamp, Karonga (29 June, 1904 ; no. 32, and 2 July, 1904 ; 
по. 35). 
280. NAVICULA ($ PINNULARIA) Dacrytus, Ehrenb., er Van Heurck, Synops. 
Liat, Belg. t. 5. fig. 1. 
Тапрапу ка. — [п swamp, Kituta (26 Aug. 1904 ; no. 80). 
281. NavicuLA ($ PixNULAmIA) vrnipis, Këte. l.c. t. 30. fig. 12; Van Heurck, 
l. e. t. 5. fig. 5. 
Victoria Nyanza.—In swampy pools, near Bukoba (20 Apr. 1905 ; no. 251). 
282. NavicULA ($ PixNULARIA) CARDINALIS, Ehrenb. in Abh. p. 19 (1840) ; 
W. Sm. Brit. Diat. 1. t. 19. fig. 166. 
Victoria Nyanza.— With the preceding species, but not so abundant 
(no. 251). 
Genus STAURONEIS, Ehrenb. 
233. STAURONEIS ANCEPS, Ehrenb. in Phys. Abh. Akad. Wiss. Berl. 1841 
(1843), p. 422 ; Cleve, Synops. Navic. Diat. i. (1894) p. 147. 
Nyasa.—In shore-pools, Nkata Вау (23 June, 1904 : no. 22). 
Victoria Nyanza.—In swampy pools, near Bukoba (20 Apr. 1905 ; no. 251). 
Genus SCHIZOSTAURON, Grun. 
284. SCHIZOSTAURON  CRUCICULA, Grun. in Cleve, New or little-known 
Diat. р. 16 (1881).—Stauroneis Crucicula, Cleve, Synops. Navic. Diat. i. 
(1894) p. 151. 
