THE TANGANYIKA PROBLEM. 
243 
The otocysts lie behind the pedal ganglia, and the 
otocyst nerves pass directly behind the cerebro-pedal and 
pleuro-pedal connectives to the cerebral ganglia on each 
side. The otocysts are not large, and are round, as 
distinguished from those of Nassopsis. The otoliths are 
small, rectangular or barrel-shaped, and numerous. 
The reproductive apparatus is very simple, and in both 
sexes consists of a genital gland which occupies the upper 
surface of the two last whorls of the animal’s body. This 
Fig. 25. — Lingual dentition of Paramelania aamoni. 
gland is put in connection with a large non-convoluted 
oviduct or vas deferens, as the case may be, by a number 
of fine tubes ; and both ducts pass beneath the intestine 
and open just behind the anus in a large slit. 
The genital duct in both sexes is much enlarged within 
the mantle cavity, somewhat in the manner of the same 
structure in the genus Typhobia. But in Bythoceras it is 
quite destitute of the singular organ which 1 described as 
an evertible penis in the male By phobia .* 
* “Quart. Journ. Micr. Sci.,” Vol. 41, 1898, p. 191, loc. cit. 
16* 
/ 
