The Freshwater Algae of Africa. 



521 



p. clxxiv) constitute the aquatic members of the genus Hormidium, as 

 enumerated by Heering (op. cit. p. 47). Apart from the character of 

 the zoospores and the Hormidiwm-like aspect of the cells, the species 



fc 



"> 



Fig. 13. — Hormidium rivulare, Kuetz., ordinary filaments 

 knee-like bending. Allfigures x 750. 



Fig. c shows a 



in question also differ from Ulothrix in the occurrence of ready 

 splitting of the filaments and in the nature of the chloroplast. 

 Although the latter is not properly known in H. fluitans,* in the other 

 two species it differs markedly from that of Ulothrix in its circular or 



* To judge by the figures in 'J'. E. Hazen, Ulotrich. and Chaetoph. United 

 States (Mem. Torrey But Club, xi. 1902, PI. XXII, figs. 7-9), however, the 

 chloroplast is not nearly so sharply defined in this species. 



