56 



food yolk within them, and increase greatly in size (fig. 56). 

 When the eggs are fully developed the vitellogenovis cells, 

 which have served to nourish them, having nothing 

 further to do, rapidly degenerate and eventually 

 disappear. According to Lecaillon (14), in some Collembola 

 {e.g., Pajnrius) intra ovarian jDi'olongations of the wall of 

 the ovary are developed, and serve to assist the vitello- 

 genous cells in the elaboration of food m.aterial for 

 absorption by the eggs. In Anurida, according to that 

 writer, these prolongations are only very slightly 

 developed. For the details of the process of oogenesis the 

 student is referred to the works of Lecaillon and of 

 Claypole (31). 



v.— EMBEYOLOGY. 



The eggs of Anurida when freshly laid are pale 

 yellow in colour, with a smooth, glistening surface. As 

 development proceeds they darken, and eventually become 

 dark orange. They are spherical in form, and each 

 measures on an average about 30 mm. in diameter. They 

 are deposited by the female in little groups, which are 

 usually to be found in plent}^ about the shores of Port 

 Erin Bay. They occur in the furthermost recesses of the 

 fissures in the rocks, and may be obtained by splitting 

 open the latter in the manner already mentioned (p. 8). 

 These groups consist of from seven or eight up to twenty 

 or thirty eggs, which are laid together in an irregular 

 fashion (Plate VIL, fig. 69). The individual females 

 appear to take no pains to keep their own eggs separate 

 and distinct from those of their fellows, and through this 

 cause large confluent masses, often consisting upwards of 

 a hundred eggs, may be met with. 



The relatively large size of the eggs of Anurida 



