246 THE JOURNAL OF BOTANY 
Vanheurckia africana, sp.n. Cellula ut in visa aspectu 
valyulari rhomboideo-lanceolata, polis obtusis; nodulo centrali 
paullo elongato ; striis validis et conspicuis, iis transversis 10 in 
10 », iis longitudinalibus 9 in 10; long. valv. 196 »; lat. max. 
44. (Fig. 18. 
This large and handsome species has the same outward form 
as V. rhomboides (Ehrenb.) Bréb., but the valves are of consider- 
ably larger dimensions, and both the longitudinal and transverse 
striations are much coarser than in any known form of that 
species. 
Lynepya contorta Lemm. in Forschungsber. Biol. Stat. Plén. 
vi. 1898, p. 202, t. 5, f. 10-18. The filaments were 1°6-2 » in 
examples tend to confir y previous remarks,* and also the 
suggestions of Ostenfeld,} that the limnetic species of L a 
require complete revision. The specimens from the Albert Nyanza 
do not agree with L. circwmcreta, differing especially in the 
Microcystis densa, sp.n. Cellulx globose, late eruginose, 
p. crass, pseudovacuol. absente, in coloniis permagnis (long. 
1400 p, lat. 415 ») densissime confertis; coloniis elongatis et sub- 
cylindricis, polis rotundatis versus attenuatis. (Figs. 6-7.) 
is species stands near to M. pulverea (Wood) Migula in the 
crowded nature of its cells and in the absence of “ pseudovacuoles”’ 
(gas vacuoles), but the cells are rather larger and the colonies of 
vastly greater dimensions. 
Description or Pirate 498. 
1. Tetraédron tetragonum (Nig.) Hansg. forma arthrodesmiforme. x 500. 
x 1000. 5a b. 
Fig. 
2-4. Spirulina laxissima G. 8S. West forma, 
v 2- 
Asterocystis smaragdina (Reinsch) Forti. All x 500. Fig. 13 is the earliest 
stage in the formation of a new plant; fig. 14 is one of the adult filaments. 
17. Katagnymene palustris, sp.n., x 500. 18. Vanheurckia africana, sp. 0., 
x 500. The striations are only indicated on a small area of the valve. 
cone atle vi) etn aemie nisin ce ete! ane 
* 
- S. West in Journ. Linn. Soc. Bot. xxxviii. 1907, p. 175. 
+ C. H. Ostenfeld, «« Phytoplankton aus dem Victoria Nyanza,” Engl. Bot. 
Jahrbiich. v. 1908, p. 335 (e. fig. 2). 
