130 MR. С. S. WEST ON THE FRESHWATER ALGÆ 
This species was in great abundance in the plankton of Victoria Nyanza, 
the locality from which Sehmidle originally described it. The semicells 
possessed either five or six processes, which exhibited considerable variation 
in the denticulation. The denticulation of the under surfaces of the processes 
was commonly much more pronounced than that of the upper surfaces, but 
in some few cases the denticulation was almost equal all round the processes. 
Each process was terminated by three or four short spines. 
Var. ACULEATUM, Lemm. т Abh. Nat. Ver. Brem. xvi. (1899) p. 344, t. 1. 
figs. 10, 11. 
Long. sine proc. 36-38 ш; lat. sine proc. cire. 23-25 p, cum proc. 103- 
128 ш; lat. isthm. 9 д. 
Victoria Nyanza.—Abundant with the type (nos. 249 and 252). 
This variety was quite as abundant as the more typical form, and the semi- 
cells similarly possessed either five or six processes. It appears to differ from 
S. limneticum in two principal features:—the body of the semicell is relatively 
much smaller, and the processes are aculeate. 
Lemmermann’s specimens were from the plankton of Lake Wakatipu, New 
Zealand, and the African examples differed from his in the fewer and more 
irregularly disposed aculei, which were strongly reminiscent of those on the 
processes of S. aspinosum, Wolle, and S. acanthastrum, W. & G. S. West. 
Some individuals were noticed which possessed a few sharp aculei on the apex 
of the semicells near the bases of the processes. 
137. STAURASTRUM TOHOPEKALIGENSE, Wolle, Freshw. Alg. U.S. (1887) 
р. 45, t. 59. figs. 4, 5.—8. nonanum, W. B. Turn. т K. Sv. Vet.-Akad. Handl. 
xxv. (1893) no. 5, p. 119, t. 15. fig. 14. 
a. Forma triangularis : long. sine proc. 51 р, cum proc. 86-91 ш; lat. sine 
proc. 35-36 и, cum proc. 90-96 ш; lat. isthm. 16:5 д. 
b. Forma quadrangularis : long. sine proc. 49 и, cum proc. 84 p ; lat. sine 
proc. 33-34 u, cum proc. 76-78 ш; lat. isthm. 16 p. 
Victoria Nyanza.—Plankton, Bukoba (18 Apr. 1905 ; no. 249, and 21 
Apr. 1905 ; no. 252). 
Triangular and quadrangular forms of this species were equally abundant 
in the plankton of Victoria Nyanza. They were typical as regards pro- 
portions and length of processes, and the latter possessed two or three 
divergent spines at their apices. These are the first specimens of the type 
form which have been recorded with more than two spines on the processes, 
although three spines are generally found on the described varieties of this 
species. 
Schmidle has recorded the var. quadrangulare, W. & С. S. West, from 
Victoria Nyanza, but no specimen I examined possessed the proportions of 
that variety. 
