BY H. LEIGHTON KESTEVEN. 629 



inward inferior face of each ganglion, and giving rise to two stout 

 and two fine nerves, is worthy of note; they occur in Littoi-ina, 

 and are perhaps represented by slight swellings in the same 

 situation on the pedal ganglia of jS^assopsis (vide Moore, 13, pi. 20, 

 f. 7). _ 



Genitalia {^) (fig. 3). The gland (fig. 3, gl.) is situated on the 

 superior face of the visceral coil; its lobules are arranged around 

 several centres, each centre apparently communicating with the 

 vas deferens through one main canal. The vas deferens (fig. 3, 

 v.d.) is situate on the axis of the coil, and is very much convoluted. 

 Arrived at the anterior end of the liver it proceeds, parallel with 

 the rectum, straight along the mantle; a little posterior to the 

 anus it takes a sharp turn in towards the body, thence it con- 

 tinues, still as a closed vas deferens, along the bod}'- to the penis 

 (fig. 3, p.). This is situated on the right side, almost under 

 the snout. The seminal products pass through it, not along a 

 groove on its side, as in Littorina (fig. 8). 



Genitalia (9) (fig- ^) '■ — The gland, macroscopically, is the same 

 as that of the male, except that it is larger and the centres of 

 arrangement are not so distinguishable; some of the lobes extend 

 round the outer side onto the inferior surface. The ovules 

 (tig. 9) may be seen to be arranged around the edges of the 

 lobules. The oviduct (fig. 4, ovid.) occupies the same position as 

 the vas deferens, and is convoluted as much. The uterus (fig. 4, 

 ut.) is placed on the mantle between the rectum and body; during 

 fecundity it is much enlarged, and at such times the rectum lies 

 in a groove on its inward side; at the posterior end, at the 

 junction of the oviduct, there is a single convolution. Its walls 

 are strengthened by muscular bands which may be seen from 

 outside to form slight constrictions. From its anterior end, at 

 the same position at which the vas deferens turns into the body, 

 the uterus may be seen to give off a short tube, which opens into 

 a groove (fig. 4, ovip.) running along the body; this groove 

 terminates in the same situation as the penis, by its two walls 

 dividing and becoming enlarged into flat attached lobes. Except 

 during the period of fecundity, the whole of both the male and 



