Tin- Freshwater Algai of Africa, 



i t5 



I have only seen very few specimens of this form, which in dimen- 

 sions and shape is more like 0. ehrenbergii, Menegh. (c/. especially the 

 var. coneavum of Schmidle, in Engler's Bot. Jahrb., xxiii, 1897,p. 256), 

 whilst the yellowish-brown colour and fine striation of the membrane 



Fig. 22 



-Closterium malinvernianum, De Not., forma major, nov. form, 

 x 180. 



bring it nearer to C. malinvernianum, De Not. Towards the ends of 

 the cells the striae give the impression of being comjiosed of numerous 

 minute granules. 



5. Closterium acerosum (Schrank), Ehrenb. ; \Y. & G. S. West. op. 

 cit, i, 1904, p. 146, PI. XVIII, figs. 2-5. 



Samples 3, 34a, 35. 



The specimens in sample 3 had very markedly truncate apices (lat 

 apic, 6 jx), although otherwise typical; some of the individuals were, 

 however, rather short (long, cell., 255-480 /x, ; lat.. 36-37 /x). The 

 specimens with a truncate apex were described by G-utwinski as var. 



