101 МК. G. S. WEST ON THE FRESHWATER ALGJE 
Order CONJUGATA, 
Family ZYGNEMACER. 
Subfam. MESOCARPER, 
Genus MOUGEOTIA, Ag. 
A number of sterile species of this genus were observed, principally from 
the Tanganyika region. No trace of spore-formation was observed in any 
of them. 
Tanganyika.—In swamp, Kituta (23 Aug. 1904; по. 72). In plankton, 
Lofu River (5 Oct. 1904 ; nos. 123 and 124). 
Subfam. ZYGNEME X. 
Genus DEBARYA, Witt». 
18. DxBARYA AFRICANA, sp. п. (РІ. 5. figs. 8—4.) 
D. cespitibus laxe intricatis, cellulis vegetativis diametro 4—8-plo longi- 
oribus, pyrenoidibus 5-8 in chromatophora unoquoque ; Zygosporis ubi conju- 
gatione scalariformi productis, globoso-ellipsoideis, magnis, tubo conjugatione 
complentibus et in gametangiis immersis, axe longiore transverse disposito ; 
membrana zygospore glabra; membrana gametangiorum suberassa; gamet- 
angiis szepe tortis. 
Crass. cell. veget. 23-26 р; lat. Zygosp. 96 ш; long. zygosp. 50 p. 
Nyasa.—In swamp, Kota Kota (20 June, 1904 ; no. 18). 
As in other species of Debarya ihe gametangia undergo a change subse- 
quent to conjugation. In this сазе the cell-walls increase considerably in 
thickness, and during this process а narrow pit arises in the middle of each 
transverse wall (vide Pl. 5. fig. 4). The zygospore is large and occupies 
the whole of a greatly swollen conjugating-tube, extending on each side to 
the outer walls of the gametangia. 
D. africana is nearest to D. immersa, W. West (Mougeotia immersa, 
W. West, in Journ. Bot. xl. (1902) p. 144), a species only known from India, 
but is distinguished by its much longer vegetative cells, its larger, smooth, 
and more completely immersed Zygospores, and by the thickened walls of the 
gametangia. 
Genus ZYGNEMA, Ay. 
Sterile species were observed from :— 
Tanganyika.—In swamp, Kituta (26 Aug. 1904; по. 80). In plankton, 
Lofu River (5 Oct. 1904 ; nos. 123 and 124), 
