OF THE THIRD TANGANYIKA EXPEDITION. 107 
Norr.—Sterile species of Spirogyra were observed from the following 
localities :—Nyasa. In swamp, Kota Kota (20 June, 1904; no. 18). In 
pools, on shore, Nkata Bay (23 June, 1904; no. 22). Among weeds, in 
swamp, Karonga (2 July, 1904; no. 34).— Tanganyika. In swamp, Mbete 
(28 Sept. 1904 ; по. 108). In plankton, Lofu River (5 Oct. 1904 ; nos. 123 
and 124); this was a large species, similar to 5. crassa, Kütz.; crass. veg. 
cell. 114-132 u ; diam. zygosp. immatur. 100-104 д. 
A fact of some interest is the complete absence from the collections of any 
species of Spirogura with replicate extremities to the vegetative cells. 
Family DESMIDIACEZE. 
Subfam. SACCODERM A. 
Genus GONATOZYGON, De Bary. 
26. Goxarozyaox MONOTÆNIUM, De Bary, in Rabenh. Alg. (1856) по. 533; 
И’, & G. S. West, Brit. Desm. i. (1904) p. 30, t. 1. figs. 1-7.—G. Ralfsii, De 
Bary, Conj. (1858) p. 76, t. 4. figs. 23-29. 
Tanganyika.— In plankton, Lofu River (5 Oct. 1904; nos. 123 and 124). 
97. Gonarozycon KiwaHaNr, (Arch.) Rabenh. Fl. Europ. Alg. iii. (1868) 
р. 156; №. & G. S. West, l c. p. 35, t. 2. figs. 1-3. 
Nyasa.—In swamp, Kota Kota (20 June, 1904 ; no. 18). 
Victoria Nyanza.—In swampy pool, near Bukoba (20 Apr. 1905; no. 618). 
Genus CYLINDROCYSTIS, Menegh. 
98. CYLINDROCYSTIS sUBPYRAMIDATA, W. $ G. S. West, in Bot. Tidsskr. 
xxiv. (1901) p. 162, t. 2. figs. 8-11. 
Long. 26-29 р; lat. 16-18 p ; lat. constrict. 15-16 д. 
Victoria Nyanza.—In swampy pool, Bukoba (20 Apr. 1905; по. 618). 
Tanganyika.—Among weeds, mouth of Malagarasi River (16 Jan. 1905 
no. 611). 
Genus NETRIUM, Zütkem. 
29. Nerrium Drerrus, (Ehrenb.) ftzigs. § Rothe, in Rabenh. Alg. no. 508 
(1856); W. & G. S. West, Brit. Desm. i. (1904) p. 64, t. 6. figs. 14-16.— 
Penium Digitus, Bréb. in Ralfs, Brit. Desm. (1848) p. 150, t. 25. fig. 3. 
Tanganyika.—In swamp, Kituta (23 Aug. 1904 ; no. 72). 
Forma parva et angustior : long. 112-140 ш ; lat. 27-32 p. 
Victoria Nyanza.—In pools near the shore, Bukoba (20 Apr. 1306 ; no. 251). 
Tanganyika.—In swamps, Kituta (26 Aug. 1904 ; no. 80). 
