16 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 
