Contributions to Our Knowledge of the Freshwater Algae of Africa. 57 
Sample 311 (not uncommon, but mainly sterile). 
Z. cyanospermum, Cleve, appears hitherto only to have been recorded by 
Oleve from Sweden and by Larsen from Grreenland. The South African 
specimens do not entirely agree with Cleve's diagnosis and figure, but there 
can be no doubt that they belong to this species. The vegetative cells and 
the zygospores are somewhat larger, but in no case did the length of the 
cells amount to more than three times the breadth; in fact in many of 
the threads, in which active division had evidently taken place, the length 
Fig. 2Q.—Moitgeotia tiherosperma, W. & Gr. S. West, a and h, cells with ripe 
zygospores, c, small part of a vegetative thread, a and h x 1000 ; c x 900. 
of the cells scarcely exceeded their breadth. The zygospores were in part 
almost completely spherical (Fig. 25, A), but here and there an elliptical one 
was encountered. The outer layer of the zygospore-membrane is relatively 
thin and transparent, the second layer more or less strongly thickened 
(Fig. 25, A, lowest zygospore) and deeply pigmented, exhibiting various 
shades of blue, from a deep greenish-blue to a deep violet or practically 
black colouration. 
Some of the sterile Zijg tiema-thre'cids in the same sample, and presumably 
belonging to the same species, were provided with a wide and often irregular 
mucilage-sheath (Fig. 25, 0). A few of these threads, with an especially 
