The Freshwater Algae of Africa. 551 



major ca. triplo longior quain axis minor ; a latere visae elliptico- 

 oblongae, lateribus fere parallelis, polis leviter rdtundatis (Fig. 26). 



Samples 1, 8, 9, 19. 



This species is evidently of common occurrence in the Cape Peninsula. 

 The characteristic features ai-e the rounded basal angles, the convex 

 sides which gradually converge more and more markedly from the base 

 to the apex, and the slightly flattened and ret use apex (Fig. 26). 

 There are two pyrenoids in each semicell. The flattened apex varies 

 considerably in width and the refuse character is sometimes more 

 sometimes less pronounced. 



" ■ 



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I 



Fig. 26. — Cosmarium capcnse, De Toni, var. minor, nov. var.. x 600. 



The specimens are appreciably smaller than those originally described 

 by Nordstedt (loc cit.), although Messrs. West (On some Desm. of the 

 United States, Journ. Linn. Soc, Bot., xxxiii, 1897, p. 301, PI. XVII, 

 fig. ■'< i have already recorded a forma minor, whose dimensions approxi- 

 mate more closely to those of the specimens found in the present 

 collections. The most important differences as compared with 

 Nordstedt's specimens, however, lit' in the shape of the side- and 

 end-views (Fig. 26). The end-view is a narrower and more elongated 

 ellipse, whose ends are not so markedly rounded, whilst in side-view 

 the almost parallel sides of the semicells are noteworthy. In the latter 

 respect our specimens are like a form described by Borge (Ueb. trop. 

 u. subtrop. Suesswasser-chlorophyc, Bih. K. Sv. Vet.-Ak. Eandl.,xxiv, 

 Aid. iii, No. L2, p. 22. Tab. 11. fig. 50), which is, however, consider- 

 ably larger and lias an end-view like that of Nordstedt's specimens. 

 Borge's form has a punctate membrane, and in this connection it may 

 he n lent io lie, 1 thai the individuals in the present samples in some cases 



