The Freshwater Algae oj Africa. 541 



Genus CYLINDKOCYSTIS Menegh. 



1. Gylindrocystis crassa, De Bary, op. '-if., pp. 37, 74, Tab. NIL 

 Pig. C, 1-12; W. .V G. S. West, op. c,7., i, 1904, p. 59, PI. IV, 

 figs. 33 38 (Fig. 20, .1). 



Samples 8, 9, 19, 50 (here common), 51. 



Long, cell., 30-50 fi; lat. cell., 18-25 /x. 



Iu sample 50 the individuals mostly had thick membranes, whilst 

 large masses of fat occurred in the cells, which were evidently in more 

 or less of a resting condition (Fig. 20, A). Side by side with speci- 

 mens of the typical shape were others in which one end was more or 

 less truncate, whilst the other was broadly rounded ; one end was 

 sometimes rather broader than the other (Fig. 20, A, the two left-hand 

 individuals). 



2. Gylindrocystis ornata, n. sp. (Fig. 20, C.) 



C. mediocris, cellulis diametro ca. duplo longioribus, in media parte 

 modice constrictis ; semicellulis ovalibus, prope mediam partem latis- 

 simis, polis rotundatis vel exigue truncatis ; membrana rubescente, 

 granulis parvis numerosis in tota superficie obtecta ; chromatophora 

 processibus paucis magnis, pyrenoide singulo. 



Long, cell., 54-57 fx] lat. cell., 27-30 p. 



Sample 50 (rare). 



This species is distinguished from all those hitherto described by the 

 form of the cell and the granulation of the membrane. The latter is 

 faintly reddish and provided with numerous fine granules, which cover 

 it uniformly (Fig. 20, C). 



Genus NETKIUM Naegeli. 



1. Netrium digitus (Ehrenb.), Itzigs. & Rothe ; W. & G. S. West, 

 op. cit, i, 1904, p. 64, PI. VI, figs. 14-10. 



Samples 2 (very rare), 50. 



Long, cell, 180-210 it; lat. cell., 45 -54 fi. 



2. Netrium oblongum (De Bary), Luetkemueller, Zellmembr. d. 

 Desm., Beitr. z. Biol. d. PH., viii, 1902, p. 407; W. & G. S. West, 

 op. cit., i, 1904, p. 66, PI. VIII, figs. 1-3. (Syn. : Penium oblongum, 

 De Bary.) 



Var. cylindricum, W. & G. S. West, Notes on Freshw. Alg., iii, 

 Journ. Hot.. 1903, p. 8, PI. CDXLVI, tig. 10; op. cit., p. 67, PL V, 

 fig. 7. 



Samples 8, 9, 37, 5t >. 



Forma curvata, now form (Fig. 20, II). 



