410 



Mr. G. C. Robson on the 



Female Organs. (Figs. 6 & 7.) 



The oviduct follows the usual course downwards from the 

 ovary. In the neighbourhood of the stomach it gives off a 

 .spermatheca of a rudely ovoid shape. The oviduct then 

 becomes convoluted as in P. ventrosa, straightens itself out 

 again, and runs parallel to the ''uterus" and its glandular 

 annexe along the right-hand side of the pallial cavity 

 external to the " uterus." It terminates in a small aperture 

 adjacent to the uterine aperture and anus. The lower end of 

 the oviduct is very slender and its aperture exceedingly 



Fis-. 6. 



H. nosophora, X 22. Female reproductive system. 



. = ovary, oviduct, and spermatheca ; = accessory giaud 



and uterus ; -.-,-.-. - = rectum. 



small, and it is very difficult to see how intromission is 

 effected. Fertilization is internal, however, as spermatozoa 

 may be frequently found in the spermatheca. It is similarly 

 difficult to imagine how tlie fertilized ova find their way into 

 tiie uterus, as they must first be shed into the pallial cavity 

 and then be drawn into the uterus. The problem is the same 

 in such forms as Melania and Tanganyikia (Moore, 7), in 

 which a groove connects the oviducal aperture with the 

 brood-pouch. 



