492 Annals of the South African Museum. 



(1907, p. 123) * without name, as a " second form " of Volvox, from 

 Nebraska. Subsequently Shaw (1916, p. 253) named it Besseyosphaera 

 Powersi ( = Volvox Powersii Printz, p. 59), the asexual colonies alone 

 having been observed by Powers ; apparently, since there are no 

 further references to it in the literature, it has never again been 

 recorded. It resembles the present species in (1) the great size of 

 the colonies, often over 2 mm. and up to 2-5 mm. in diameter, and (2) 

 the large number of daughter colonies, up to 78 being recorded. 

 Further, judging from Powers' remarks it is slow in development. 

 But, according to Shaw, the gonidia are not differentiated until after 

 birth, and on this feature, combined with the absence of protoplasmic 

 connecting strands, Shaw founded his new genus Besseyosphaera, 

 which he regarded as intermediate between Pleodorina Shaw and 

 Volvox. 



Powers found the asexual colonies in a pond which was deeper 

 than those in which Volvox usually occurs in Nebraska, and " found 

 nothing resembling it' subsequently (Powers, 1908, p. 142). It 

 seems possible that on a fuller examination it might prove to be 

 identical with the Kimberley material described here as Volvox gigas. 

 On the existing descriptions, however, it must be regarded as distinct. 

 The resemblance of V. gigas to Pleodorina is certainly very remote ; 

 it is unmistakably much more nearly allied to Volvox than to Pleo- 

 dorina, and seems to be a somewhat primitive form belonging to the 

 section Merrillosphaera (according to Printz, genus according to Shaw). 



Powers' photographs of other species of Volvox are so excellent 

 that it is most unfortunate that he apparently published none of 

 either this " second form " described in his first paper or of another 

 outstanding species which he named Volvox perglobator and which 

 closely resembles V. Rousseletii G. S. West. 



The field observations given below (pp. 38 to 39) show how much 

 slower in development V. gigas is than the associated V. Rousseletii. 



2. Volvox africanus G. S. West (1910, p. 102, and 1918, p. 1). 

 (Text-figures 4 and 5, Plates XXX (fig. E) to XXXIII.) 



Asexual colonies in all stages of development. No sexual colonies 

 seen. Mature colonies large, over 1 mm. in length and nearly 1 mm. 

 in width. 



* Unfortunately, Powers' original paper has not been available for reference ; 

 the substance has had to be gathered from references by other authors, particularly 

 Shaw, and from Powers' own remarks in his subsequent paper (1908, p. 142). 



