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 papilla 1 , 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 

 branchiae. 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 branchiaa 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, 25) 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 



