мы 
OF THE THIRD TANGANYIKA EXPEDITION, 17 
Vahambwera Point (24 June, 1904 ; no. 24). In swamp, Kambwelagoon 
near Karonga (27 June, 1904 ; no. 29). 
b. Crass. trich. 1 д; long. cell. 5-6 р. 
Tanganyika.—In plankton, Lofu River (5 Oct. 1904 ; по. 124). 
This minute Lyngbya exhibited considerable variation. The range of 
diameter was from 1 » to 1:5 р, and the length of the cells from 3:3 to 6 p. 
In all cases a strong puncta or large granule was visible on each side of the 
dissepiments. In some instances the filaments were regularly twisted into 
a lax spiral, in others they were only curved, and very rarely they were 
almost straight. The spiral specimens only differed from L. Lagerheimit, 
(Méb.) Gomont, in the slightly longer cells, and in some of them the apical cells 
were very slightly narrowed and faintly capitate as in L. Nyasse, Schmidle. 
I place the plants observed under L. bipunctata, Lemm., mainly owing to 
the length of the cells. They appear to me to combine the characters of 
L. Lagerheimii, L. bipunctata, and L. Nyasse, three Lyngbyas which would 
perhaps be better regarded as constituting one species with well-marked 
punctæ and with filaments which frequently become twisted into a lax spiral. 
Particularly interesting was the finding of narrowed and faintly capitate 
apical cells in the spirally twisted forms. Precisely the same plant was 
observed from stones in a swamp as occurred in the plankton. 
312. LYNGBYA PERELEGANS, Lemm. in Abh. Nat. Ver. Bremen, xvi. (1899) 
p. 355 ; xviii. (1904) p. 153, t. 11. figs. 13, 14. 
Crass. cell. 1°5—1°8 д. 
Tanganyika.—In plankton, Niamkolo (Aug. 1904 ; nos. 39 and 52) and 
near Kala (19 Nov. 1904 : no. 170). 
313. LvxaByA LIMNETICA, Lemm. in Bot. Centralb. Ixxvi. (1898) p. 154 ; 
Forschungsb. Biol. Stat. Plön, x. (1903) p. 151. 
Tanganyika.—In plankton off Niamkolo Island (29 July, 1904 ; no. 36). 
Genus PHORMIDIUM, Кш. 
314. Рновмготем FOVEOLARUM, (Mont.) Gomont, in Ann. Sci. Nat. T° sér., 
Bot. xvi. (1892) p. 164, t. 4. fig. 16. 
Crass. trich. 1:4-1:8 p. 
Tanganyika.—Hpiphytic on Plectonema Wollei, Komba Bay (10 Oct. 1904; 
no. 134). On rocks, among Lyngbya Martensiana and L. versicolor, Mbete 
(29 Sept. 1904; по. 114). Оп rocks dredged in 2 or З fathoms, Niamkolo 
Harbour (7 Sept. 1904 ; no. 87). 
The varied habit of this species is worthy of comment. 
315. PHORMIDIUM TENUE, (Menegh.) Gomont, l. c. p. 169, t. 4. figs. 23-25. 
Tanganyika.—On stones, shores of lake Niamkolo (1 Aug. 1904 ; no. 44). 
In swamp, Kituta (23 Aug. 1904; no. 72). Near Kala, both in the plankton 
