GASTEROPODES. 315 
but I cannot affirm that they are ocular. No sense of the presence of ex- 
ternal objects is ever shewn unless by feeling. Back bare in the middle, 
and clothed on the sides by long, flexible, extensile, subulate or awl- 
shaped branchial papille, disposed rather in rows than in bunches, and 
varying from 300 to 350 in number. These are in frequent motion, 
curving, waving, and bristling up, when the animal suffers any annoyance. 
The highest and the lowest on the side are the shortest. 
Slight variations are seen in the form and the disposal of the 
branchiz. ‘The back is sometimes bare throughout. Of eight speci- 
mens, the back was bare down to the extremity in five ; but, in the 
other three, only the upper portion of it was bare, while the lower 
part was clothed as thickly as the sides, and in rows as definite. 
The colour of the body varies from faint purple to leaden-grey, and 
in some specimens even to brownish. The branchiz are greyish purple, 
the texture of their surface resembling ivory. Carnation distinguishes the 
cornicula, while the back in their vicinity is reddish. A yellowish shade 
of the under surface denotes the internal site of the ovarium. 
This is a very prolific species. Many individuals approach the shore 
in June, July, August, and even September, when a great profusion of 
spawn is deposited on the under surface of stones. In captivity, the 
animals spawn on the sides of their vessels, in the form of spiral ropes ; 
or, swimming supine, the rope, which is always seen of the same form, 
is produced just under the surface of the water. On turning up the 
stones near low water, the spawn may be recognized, from its resem- 
blance to numerous grains of rice. When in greatest profusion, it appears 
in the general arrangement of a logarithmic curve of two or more volutes. 
The cause of this peculiar form being assumed, has been previously ex- 
plained. But the perfection of this figure depends on the motion of the 
parent being unrestrained. But peculiarities are often found, which I 
cannot pretend to explain. 
A fine specimen (Plate XLV. figs. 24, 29) spawned on 6th February, 
in two complete volutes, resembling a coarse white thread, on the back 
of an oyster-shell ; and, at the interval of a week, produced other two 
volutes at the surface of the water. Two weeks subsequent to the first 
