Contrihutions to Our Knotvleclge of the FresJiwater Algae of Africa. 53 
(Note. — Sterile, and therefore indeterminable, material of this genus was 
also encountered in the following samples : 33, 66 (several species), 86, 159, 
311, 313, 314, 316, 327, 336, 339, and 344). 
Fig. 23. — Spirogyra rivularis (Hass.), Rabenli. (?). A, small part of a filament 
showing the thick membrane and the arrangement of the chloroplasts. B, 
one of the attaching cells. C, base of a filament. A and B x 450 ; C x 50. 
aENus ZYaNEMA Agardh. 
1. Zygnenm pectbiatum (Vauch.), Agardh., Synops. alg. Scandiu., 1817, 
p. 102; Borge, op. cit., p. 33, fig. 49. (Syn. : Zygogonium pectinatum, 
Kuetz.). (Fig. nostr. 24.) 
