142 МК. G. 5. WEST ON THE FRESHWATER ALGÆ 
Tanganyika.—Plankton, off Niamkolo ( July and Aug. 1904 ; nos. 36 and 
39), near Mbete (28 Sept. 1904; no. 109), Vua Harbour (29 Oct. 1904 : 
no. 150), near Kalambo (5 Nov. 1904 ; no. 154), near Chamkaluki (15 Nov. 
1904 ; no. 160), near Kala (19 Nov. 1904 ; no. 170), near Kirando (1 Dec. 
1904; no. 175), in middle of lake crossing from Rumonge to Uvira (30 Jan. 
1905; no. 218), near Ndauvie (7 Feb. 1905; no. 227), and near Baraka 
(24 Feb. 1905 ; no. 240). 
Victoria Nyanza.—Plankton, near Bukoba (18 Apr. 1905 ; no. 249). 
This Alga was very frequent in the plankton, especially of Tanganyika. 
The envelope surrounding the colonies is always very hyaline, and no colonies 
were observed of more than eight cells. The faint apiculus at each pole is 
very characteristic, although exceedingly slight. Two chloroplasts were 
generally present in each cell. The plants observed were identical in every 
respect with those which occurred in the plankton of certain Trish lakes 
(vide Trans. Roy. Irish Acad. xxxiii. sect. B, 1906, p. 107). 
Genus NEPHROCYTIUM, Näg. 
170. NEPHROCYTIUM AGARDHIANUM, Лад. Gatt. einz. Alg. (1849) p. 79, 
t. 3c. figs. а-р. 
Nyasa.—In swamp, Karonga (2 July, 1904 ; no. 34). 
Тапрапу а. — п swamp, Kituta (23 & 26 Aug. 1904 ; поз. 72 and 80). 
171. МЕРНВОСУТГОМ LUuNATUM, West, in Journ. Roy. Mier. Soc. (1892) 
p. 736, t. 10. fig. 49. 
Tanganyika.—In swamp, Mbete (28 Sept. 1904 ; no. 108). 
Subfam. TETRAEDRE x. 
Genus TETRAEDRON, Kiitz. 
172. TETRAÉDRON TRIGONUM, (Nég.) Hansg. in Hedwigia, xxvii. (1888) 
p. 130.—Polyedrium trigonum, Ndg. Сан. eine. Alg. (1849) p. 84, t. 4 n. fig. 1. 
Diam. cell. sine spin. 14-16 ; long. spin. 5-65 д. 
Victoria Nyanza.—Among Utricularia, near Entebbe (1 May, 1905; 
по. 620). 
173. TETRAEDRON MINIMUM, (A. Br.) Hansg. 1. е. р. 131.—Polyedrium 
minimum, A. Br. in Rabenh. Fl. Europ. Alg. iii. (1868) p. 62. 
Trigonal forms : Nyasa.—In scrapings from bottom of s.s / Guendolen ' at 
anchor S. end of lake (15 June, 1904; no. 577). In swamp, Karonga 
(2 July, 1904 ; no. 34). 
Tanganyika.—In plankton, off Niamkolo Island (29 July, 1904 : no. 36). 
In swamp, Toa (10 Jan. 1905 ; no. 168). 
