140 MR. G. $. WEST ON THE FRESHWATER АІС 
Genus DIMORPHOCOCCUS, A. Br. 
161. Dimorpnococcts LUNATUS, А. Br. Alg. Unicell. (1855) р. 44; Rabenh. 
Fl. Europ. Alg. in. (1868) pp. 6 (cum fig.) et 35 : West, in Journ. Roy. Mier. 
Soc. (1892) p. 735, t. 9. fig. 39.—Scenedesmus radiatus, Reinsch. 
Diam. colon. usque ad 104 w; long. cell. 14-16 д. 
Tanganyika.—In swamp, Mbete (28 Sept. 1904 : no. 108). 
Victoria Nyanza.—Plankton, near Bukoba (18 Apr. 1905 ; no. 249). 
Genus ANKISTRODESMUS, Corda. 
162. ANKISTRODESMUS FALCATUS, (Corda) Ralfs, Brit. Desm. (1848) p. 180, 
t. 34. fig. 2.—Micrasterias falcata, Corda, 1835. Ankistrodesmus fusiformis, 
Corda, 1838 (ex parte). Rhaphidium fasciculatum, Aütz. 1845. К. poly- 
morphum, Fresen., var. falcatum, Aabenh. Fl. Europ. Alg. iii. (1868) p. 45. 
Nyasa.—Swampy lake margin, Domira Вау (19 June, 1904 ; no. 579). 
Tanganyika.—Plankton, Lofu River (5 Oct. 1904 ; no. 123). 
Victoria Nyanza.—Swampy pool near Bukoba (20 Apr. 1905 ; no. 618). 
Among Utricularia, near Entebbe (1 May, 1905 ; no. 620). 
a. Forma cellulis robustis lunatis, chromatophora cum pyrenoide singulo. 
Lat. cell. 5 u. 
Nyasa.—In swamp, Kota Kota (20 June, 1904 ; no. 18). 
b. Forma cellulis robustis rectis solitariis, leviter tumidis, sine pyrenoidibus. 
Lat. cell. 7 p. 
Муаза.— [п swamp, Karonga (2 July, 1904 ; no. 24). 
Var. ACICULARIS, (A. Br.) G. S. West, Treat. Brit. Freshw. Alg. (1904) 
р. 223. —Hhaphidium aciculare, А. Br. in Babenh. Alg. 1849, no. 442. 
Ankistrodesmus acutissimus, Arch. in Journ. Micr. Sci. 1862, р. 255, t. 12. 
figs. 44-57. 
Nyasa.—On stones on shore, Domira Bay (19 June, 1904; no. 17). 
Swampy lake margin, Domira Bay (19 June, 1904; no. 579). 
Var. SPIRILLIFORMIS, G. 5. West, l. с. (1904) p. 224.—Rhaphidium poly- 
morphum, var. spirale, И”. у G. S. West, in Journ. Bot. xxxvi. (1898) p. 335. 
Tanganyika.— Plankton. near Kala (19 Nov. 1904 ; no. 170). 
163. ANKISTRODESMUS NITZSCHIOIDES, sp. п. (Pl. 5. fig. 18.) 
А. cellulis solitariis, elongatis, fusiformibus, ad polum unumquemque in 
spinam longissimam tenuissimam valde attenuatis, extremitatibus spinarum 
curvatis (extremitati spine alterius poli cum ea alterius curvato in directione 
opposita); chromatophora pallide viridi, pyrenoidibus nullis. 
Long. cell. cum spin. 116-126 ш; lat. cell. in med. 3:6—4 д. 
Tanganyika.—Plankton, near Chamaluki (15 Nov. 1904 ; no. 160). 
This species stands nearest to А. setigerus, (Schréd.) G. S. West (Reinsch- 
tella? setigera, Schród. in Ber. Deutsch. Bot. Ges. xv. (1897) p. 492, t. 25, 
