OF THE THIRD TANGANYIKA EXPEDITION. 169 
287. NosToc PIsCINALE, Kiitz. Phye. general, (1843) p. 208 ; Tab. Phyc. 
ii. p. 4, t. 11. fig. 3 (1846) ; Born. $ Flah. in Ann. Sci. Nat. T° ser., Bot. vii. 
(1888) p. 194. 
Crass. trich. 4 p ; crass. heteroeyst. 5-6 ш; diam. spor. 575-175 p. 
Tanganyika.—In plankton, Kituta Bay (24 Aug. 1904; по. 74). On 
surface of swamp, Toa (10 Jan. 1905 ; no. 209). 
288. Nosroc cARNEUM, Ag. Syst. Algar. 1824, p. 22 ; Born. «у Flah. l. c. 
(1888) p. 186. 
Crass. trich. 2:8-3:5 р; long. heterocyst. 10 ш; lat. heterocyst. 55 и; 
long. spor. 9-11:5 p; lat. spor. 577—675 p. 
Tanganyika.— |n plankton, Kituta Bay (27 Aug. 1904; no. 82). 
Genus ANABAENA, Bory. 
289. ANAB.ENA FLos-AQU.£, (Lyngb.) Bréb. Alg. Eur. Falais. р. 36 (1835); 
Born. $ Flah, l. с. (1888) p. 228 ; J. Schmidt, in Bot. Tidsskr. xxii. (1899) 
p. 367. 
Forma trichomatibus curtis, spiraliter dispositis, anfractibus arctis ple- 
rumque 2-4; cellulis globosis cum granulis conspicuis paucis ; heterocystis 
intercalaribus (non terminalibus) ; sporis non vidis. 
Crass. trich. 6-7 ш; crass. heterocyst. 75-8 м. (Pl. 4. figs. 10, 11, 14, 15; 
Pl. 10. fig. 1.) 
Nyasa.—ln the plankton, Anchorage Вау (13 June, 1904; no. 9) and 
Monkey Bay (17 and 18 June, 1904 ; nos. 15 and 16) ; very abundant. 
Tanganyika.—In the plankton, near Kalambo (5 Nov. 1904; no. 154), 
near Kirando (1 Dee. 1904; no. 175), and near Utinta (5 Dec. 1904 ; 
no. 181). 
The trichomes are spirally twisted after the manner of а corkscrew, mostly 
making from 2 to 4 turns, rarely as many as 8. The cells are almost exactly 
globose, and the heterocysts were never observed to be terminal. It was the 
dominant feature of two of the Nyasa plankton collections. 
This form may be the same as the Anabaena mentioned by Schmidle as 
occurring in Lake Nyasa, and for which he suggested the name “ A. Flos- 
aqua, forma discoidea” (cf. Schmidle, in Engl. Bot. Jahrb. xxxii. (1903) 
р. 61). It is, however, rather larger than the measurements he gives for the 
specimens collected by Dr. Fülleborn. It may also be identical with 
A. spiroides, Klebahn. 
Dr. Cunnington states that on one occasion in Lake Nyasa, and on a few 
occasions in Lake Tanganyika, a yellow scum was present on the surface, 
which he attributed to immense quantities of an Anabena. He thinks that 
this appearance was the same as that noted by Livingstone and more recently 
by Mr. J. E. 8. Moore (“The Tanganyika Problem,” p. 323), who deseribes 
the surface as * appearing as if tinged with a fine golden dust." Mr. Moore, 
