Contributions to Our Knowledge of the Freshivater Algae of Africa. 51 
var. africana, F. E. Fritscli, nov. var. (Fig. 22). 
Var. cellulis vegetativis latioribus, saepe elongatis, membranis crassis, 
in parte mferiore filoruni etiam crassissimis, cliromatophoris 3-4 anfractibus 
l|--4 ; cellulis fructiferis valde iiiflatis, abbreviatis ; zygosporis ovalibus, 
apicibus late rotundatis, cellulas sporiferas noii vel fere complentibus. 
Membrana zygosporae crassa ferruginea, lamina media irregulariter sed 
dense reticulata. Ceilula radicalis plus minus elongata, rliizoidiformis et 
Fig. 22. — Spirogyra jluviatilis, Hilse, var. africana, P. E. Fritscli, vov. var. A, 
base of a filament showing the attaching cell and the thick- walled cells follow- 
ing upon it. B, a single one of the latter, on a larger scale. C, ordinary 
vegetative cells. D, rhizoid of the ordinary, and E, rhizoid of the branched 
type. F, small part of threads in process of conjugation. G, zygospore, 
showing structure of the membrane. H, small part of the latter, on a larger 
scale. J. X 30; 5 X 60; Oand x 300; D-F x 135; H x 700 about. 
vulgo contentu nullo, cellulae posteriores aut formae vulgaris aut membrana 
valde incrassata et contentu diminuto. 
Lat. cell, veg., 54-60 ; long. 3-lOplo major; lat. cell, fruct., 90-96 f^; 
crass, zygosp., 63-67 it*; long, zygosp., 78-79 (raro longior). 
Sample 331 (common, probably attached to stones in clear running water). 
This variety differs from the published descriptions of S. fluviatilis, 
Hilse, in the wider vegetative cells, the frequent presence of three chloro- 
plasts (although four are not uncommon), and in the dense reticulation of 
