Volvox in South Africa. 529 



various pools and in the vleis on the Cape Flats, the latter being 

 correlated as far as possible with weather conditions. 



Further, material has been fixed in various ways, embedded and 

 microtomed to supplement the details observed in living material, 

 particularly with regard to inversion. 



Since in some respects it has been possible to follow out the life- 

 history in the case of the Rietfontein Volvox (Volvox Rousseletii) 

 more fully than that of the Cape Flats Volvox (V. capensis) that 

 form will be described fully, the points in which the latter differs 

 from it being considered as they arise. Where nothing to the con- 

 trary is stated, the account given applies equally to both species. 

 Although much of the detail repeats the findings of earlier workers 

 (e.g. Cohn, Klein, Overtoil, Janet) in the case of V. globator in 

 Europe, it is given fully here, since V. Rousseletii and V. capensis, 

 though undoubtedly very closely allied to V. globator, yet differ 

 from it in many details, and it is important that they should be 

 known in every aspect. Moreover, there is at present no recent 

 comprehensive account of Volvox in English, Shaw's papers (1916, 

 1919, 1922, 1923) dealing more particularly with the classification of 

 the group. 



Occurrence of Volvox in South Africa. 



Since the occurrence of Volvox in South Africa has already been 

 dealt with (Rich and Pocock, p. 427), it will be sufficient here to give 

 a very brief summary of the records. 



Shaw (1922) has subdivided the genus Volvox into several new 

 genera, retaining the name Volvox for that section of which V. 

 globator is the type. As yet his classification has not been generally 

 accepted in its entirety, but both Pascher (1927, p. 462) and Printz 

 (1927, p. 58) agree that some reclassification is necessary, and the 

 latter, while not accepting Shaw's new genera as such, uses his 

 nomenclature to denominate subsections of the genus. Of these 

 subgenera or subsections three have so far been recorded from 

 Africa : 



1. Merillosphaera, represented by Volvox africanus West (Merril- 

 losphaera africana according to Shaw), apparently restricted in its 

 distribution, since it has been recorded only from Lake Albert 

 Nyanza, the Ussangu desert in Tanganyika (West, 1910, p. 102, 

 and 1918, p. 1), and more recently from the Linyanti, where it was 

 collected by the writer and Miss E. L. Stephens, and from Kimberley, 

 collected by Mr. Power (Pocock, 1933, p. 492). Possibly, like 



