The Freshwater Alqae of Africa. 



543 



granules are small, numerous, and scattered; otherwise like the type. 

 The dimensions are smaller than those given in the original diagnosis, 

 but G. S. West (Alg. Van Yean Reservoir, Journ. Linn. Soc, Bot., 

 xxxix, 1909, p. 53) has already described a smaller form. 



2. Penium phymatosporum, Nordst. ; W. & G. S. West. op. cit., i, 

 1904, p. 91, PI. VI, figs. 9-11. 



Forma paullo latior, lateribus leviter couvexis, constrictione mediana 

 plane manifesta. Long, cell., 39-43 ,,. ; lat., 18-21 fi (Fig. 20, B). 



Sample 50 (not uncommon). 



The specimens differ from the typical ones in having faintly convex 

 sides and a slightly greater breadth in proportion to the length; the 



Fig. 21.— Penium conspersum, With-., var. capense, nov. var. 



median constriction is also rather more pronounced (Fig. 20, B). This 

 form may be compared with one figured by Borge (Ueb. trop. u. sub- 

 trop. Suesswasserchlorophyc, Bih. K. Sv. Vet -Ah. Handl., xxiv, Afd. 3, 

 No. 12, Tab. I, fig. 7), which, however, lacks the faint longitudinal 

 striations. 



The chloroplast appears to be provided with a considerable number 

 of longitudinal ridges, which exhibit frequent interruptions (Fig. 

 20, B). 



3. Penium conspersum, Wittrock, Gotlands och Oelands Soetvatten- 

 salg., Bih. K. Sv. Vet.-Ak. Handl., i, 1872, p. 66. 

 Var. capense, nov. var. (Fig. 21). 



Semicellulis inflatione exigua, spatio variabili a media cellula posita 

 munitis ; membrana achroa ; alioqui typo similis est. Long, cell., 05- 

 96 /x; lat., 18-22 {J.. 



Samples 50 (not uncommon), 51. 



