﻿92 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 102 



To the left of the ctenidium, and about half its length, is the narrow, 

 tubular osphradium or "organ of smell." It is also closely welded to 

 the mantle. 



UROGENITAL SYSTEM 



Figures 38, 39 



Kidney: The renal organ is a rather large, easily seen, oval sac j 

 lying in the region between the stomach and the apex of the mantle 

 cavity. At its posterior end, where it borders the right side of the 

 crystalline style sac, it is narrow, but widens and flattens toward its 

 anterior end. The intestine is partially encased by the right side of 

 the kidney. Internally the kidney is made up of a network of thin 

 lamellae or septa, between which are the blood spaces. The lamellae 

 are arranged in a more or less regular pattern and all pointing toward 

 the center of the kidney. This pattern is easily seen through the thin 

 outer wall of the organ. No prominent renal aperture leading into 

 the mantle cavity could be found. An obscure renal duct could be 

 followed in a few specimens, which led down the right, lower side of 

 the kidney and passed along the mantle wall to an exodus beside the 

 genital orifice. 



Gonads : The gonads in this species are small and lie on the inside 

 of the whorls of the digestive gland in the spire. In living material 

 they consist of a bright yellow tubule, which gives off numerous smaller 

 branches. Eggs were observed by crushing small portions of the 

 gonads on a slide. No sperm were observed in either living material 

 or in histological sections made from preserved material. 



The genital orifice is surrounded by a small, elongate, cup-shaped 

 flap, the opening of which faces the entrance of the brood pouch a few 

 millimeters away. Eggs have not been observed passing from the 

 oviduct to the brood pouch, but it is possible that the flap of the genital 

 orifice is pressed against the pouch entrance when the animal is com- 

 pletely withdrawn into its shell. 



The brood pouch is not developed until the animal begins to reach 

 maturity. In its early formation the pouch consists of an irregular, 

 flattened hollow in the connective tissue of the back of the animal. As 

 more eggs are added and the hatched young grow, the pouch is en- 

 larged and becomes irregularly divided into small compartments. 

 Thin, transparent walls of adventitious tissue separate the various 

 groups of young, but all stages of development of the j^oung may be 

 represented in these compartments. The more advanced young either 

 push or eat their way through these thin walls to other compartments. 

 In a highly developed pouch the dorsal wall is thin enough to reveal 

 the young crawling about inside. The pouch may extend from the 

 region immediately behind the tentacles and central ganglia posteriorly 



