Contributions to Our Knowledge of the Freshwater Algae of Africa. 31 
Fig. 11. — A, Cosmarium undulatum, Corda, var. crenulatiim (Naeg.), Wittr. B, 
C. hammeri, Reinsch, var. africanum, F. E. Fritsch, nov. var. C, C. granatum, 
Breb., var. africanum, h\ E. Fritsch, nov. var. D, C. laeve, Rabenh., f. acnrtii- 
nata, n. f. E, C. laeve, Rabenh., the typical and various transitional forms. 
F, C. laeve, Rabenh., f. rotundata, n. f. G, C. rectangulare, Grmi., forma. H, 
C. granatum, Breb., forma, a, a', a", front-views ; h, h', side-views ; c, end-view. 
All figures x 950. 
