290 LILIAN SHELDON. 



threads and chromatin granules. The ovum is completely sur- 

 rounded by a thin shell, which separates the ovum from its 

 stalk. The egg-protoplasm is completley obliterated by the 

 closely packed yolk-spheres, and there is no trace in it of nuclei 

 from the follicle or stalk, these having probably become con- 

 verted into yolk. 



This is the oldest ovum which I have found attached to the 

 ovary. The youngest ovum which I found in the uterus con- 

 tained no nucleus, was surrounded by a thick shell, and was 

 closely packed with yolk. 



The subsequent stages, from that in which the first seg- 

 mentation nucleus is present, have been described in a previous 

 paper (16). 



I have never observed the formation of polar bodies in this 

 species, nor have I ever observed them on the surface of the 

 ovum in later stages, as might be expected, if they were 

 present. 



I have never observed the process of fertilization, nor do 

 I know where it takes place ; but from the fact that I have 

 never found spermatozoa in the ovary, while they are very 

 plentiful in the receptacula seminis, I would suggest that 

 the egg is fertilized in the oviducts in the region of the 

 receptacula. 



I have never found an ovum either in the ovary or upper 

 part of the oviducts, and it is very probable that, from the large 

 amount of food-yolk in the egg, a spermatozoon after entering 

 it would easily be obscured from notice. 



Summary of Events in the Maturation and Fertili- 

 zation of the Ovum of P. Capensis and P. 

 Balfouri. 



1. The ovary consists of a pair of tubes lying parallel to one 

 another and uniting anteriorly. Posteriorly they also unite 

 into a short common duct, which almost at once divides into 

 the two oviducts. The ovarian tubes are lined along the inner 

 side by a flat epithelium, which is thinner in P. Balfouri 



