468 Annals of the South African Museum. 



EXPLANATION OF PLATES. 

 PLATE IX. 



Volvox aureus Ehrenb., from Eliazer Pan, Potchefstroom, Transvaal. 

 FIG. 



A. With V. Rousseletii (the latter larger and darker), x 38. 



B. Group showing male, female, and asexual coenobia. x 70. 



C. Young female coenobium. x 108. 



D. Young male coenobium. x 116. 



PLATE X. 

 V. aureus Ehrenb., from Potchefstroom. 



A. Asexual colony with 6 daughters, one half-inverted. x 150. 



B. Somatic cells, protoplasmic connections just visible. x 800. 



C. Sperm platelets. x 1000. 



D. Female colony (polar view) with 11 ripening oospores. x 108. 



E. Two oospores in situ (still young). x 280. 



PLATE XI. 

 V. aureus Ehrenb. 



A. o and $ colony from Potchefstroom. x 83. 



B. C. From Old N'gamo. B, two female colonies, 1 male colony, and a colony 



of Pleodorina californica (reproductive). x 70. C, asexual colony with 7 

 mature daughters. x 83. 



PLATE XII. 



A, B. V. africanus G. S. West, from the Linyanti River. 

 Two asexual colonies with 3 and 2 large daughters respectively. x 110. 



C-E. V. capensis sp. nov., from the Cape Flats. 



C. Very young strain collected less than a week after the formation of the pool ; 



normal asexual colonies and a few " juveniles " formed on germination of 

 oospores. x 36. 



D. Group from an older strain ; asexual colonies, young sexual colonies with sperm 



bundles and oospheres, older sexual colonies with nearly ripe oospores. 

 The large daughters in the colony near the top on the right are preparing 

 to invert. Several colonies contain Rotifers and show signs of the damage 

 they do. x 28. 



E. Portion of sexual colony showing nearly mature oospheres (one detached) and 



a single sperm globoid. x 400. 



