464 Annals of the South African Museum. 



the protoplast. The cells vary very much in size, not only according 

 to age, but also according to the position in the coenobium. They are 

 more closely packed in asexual than in sexual colonies. The distance 

 between their centres may be twice as great at the anterior as at the 

 posterior end (of a sexual colony) 20 to 10 p.. The gonidia are late 

 in developing ; a free coenobium measuring 640 x 680 p, was noticed 

 with a few cells only just beginning to be differentiated. The daughter 

 colonies vary in number ; sometimes only 1 is present, though 8 is a 

 common number. Several colonies were found with 9 daughters, 

 three with 10, three with 12, and one with 14. On escape they 

 measure from 135 to 200 p.. Sometimes daughter colonies are found 

 in coenobia containing male and female elements (text-fig. 6, G). 



The sexual colonies (text-fig. 6, E and F) are apparently monoecious 

 and protandrous ; they may contain daughter colonies. The anterior 

 end is sometimes more pointed than the other. They are ovoid in 

 shape, often with only a slight difference in the length of the two axes 

 (Plate XXIV, figs. A and B). They are larger than the asexual colonies, 

 some attaining a diameter of 2 mm., though others are quite small. 

 The material to hand was over-ripe and male elements were rare, 

 but a few scattered sperm bundles in the midst of ripe oospores were 

 observed, 31 to 33 p, in diameter. As a rule the oospores are crowded 

 into about two-thirds of the coenobium ; sometimes a free space is 

 observed at both ends (text-fig. 6, F). The number of oospores is very 

 variable ; occasionally in an unusually small coenobium there are only 

 20 mostly there are several hundreds, even up to 700. This is a 

 larger number than has been recorded for any previously described 

 Volvox : in V. globator there are generally 30, though the number may 

 be 64 ; V. Rousseletii has 200, V. Barberi about 224, F. perglobator 

 from 300 to 400.* The oospore is densely covered with conical 

 pointed spines, spirally arranged, about 16 or 17 visible round the 

 periphery (text-fig. 4, E, and Plate XXIV, fig. C). The diameter 

 without spines is from 30 to 36 p. ; the spines vary in length from 5 

 to 7 p, ; frequently the measurements are 30 p, without spines, 40 p, 

 with spines. The oospores, it will be seen, are rather small. The 

 spines are hollow, and are rather more pointed than in the forms above 

 described (recalling those of V. Merrilli Shaw,f but shorter), the tip 



* Powers, J. H., Trans. Amer. Micr. Soc., vol. xxviii, 1906, p. 162. V. perglobator 

 is comparable to the Ovamboland Volvox in size and in its large number of 

 oospores, but is dioecious, and the somatic protoplasts form a reticulum, the 

 cell-body becoming hardly noticeable. 



t Shaw, W. R., loc. cit., vol. xx, No. 5, 1922, pi. i, fig. 3. 



