560 



Annals of the South African Museum. 



I have unfortunately been unable to obtain a side-view of this 

 species, but it is sufficiently different from those hitherto described to 

 warrant the establishment of a distinct form. In general shape the 

 semicells are not unlike those of X. antilopaeum (Breb.), Kuetz., but 

 they differ from them in the very shorl spines, in their rather different 

 arrangement, and in the end-view; '•/'. also A', mayori, <!. S. West 

 (Contrib. to our knowl. Freshw. Alg. Columbia, Mem. Soc. neucha- 

 teloise d. Sc. nat., v. 1914, p. 1041, PI. XXII. tig. 41 i 



Ym_ 31. — Xanthidiwm brevispinum, n. sp. x 600. 



Genus ABTHEODESMUS Eheenberg. 



1. AHhrodesmus incus (Breb.), Hassall, Brit. Fresliw. Alg., 1845, 

 p. 357, Tab. LXXXV, fig. 10; W. & G. S. West. op. cit., iv. 1912. 

 p. 91, PL CXIII, figs. 13-15. 



Sample 54 (very rare). 



Long. cell, sine spin.. 18 p. ; lat. cell, sine spin., 15 /;. ; crass., 9-10 ft. 



Genus STAUEASTBUM Meyen. 



1. Staurastrum striolatum (Naeg. ), Arch.; W. X- G. S. West, op. 

 cit., iv, 1912, p. 177, PI. CXX VII, "figs. 1-5. 



Sample 2 (rather rare). 



Long., 28-30 /x; lat. 24-25 /a ; lat. isthm., 9 fx. In some specimens 

 the apex of the semicell, in front-view, appeared very faintly convex. 

 The vertical view was always absolutely typical. 



2. Staurastrum punctulatum, Breb.; W. & G. S. West, op. cit.. iv. 

 1912, p. 179, PI. CXXVII, figs. 8-11, 13. 14. 



Sample 8 (rather common). 



