160 HELICnXE. 



taken for the beating of the heart ; it is irregular, 

 sometimes fast and sometimes slow. The animal is 

 blaf k, nocturnal, and subterraneous ; the mouth is 

 vertical linear; the jaw small, horny, smooth or 

 very minutely striated. 



The eggs are large compared to the size of the 

 shell ; and this explains the bluntness of the apex, 

 arising from the large size of the body of the animal, 

 on which the shell is formed before it is hatched. 



Ferussac (1807) first observed that this animal was 

 deprived of ocular points. (Essai, iii.) Nilson, in 

 1822, repeated the account, and added that the apex 

 of the tentacle was furnished with a small smooth 

 annular depression (Moll. Suec. 29.). M. Bourge- 

 gnart, on this character, has formed it into a ^enus. 



10. PUPA Lam. (Chrysalis Shell.) 



Animal like Bulimus, with four club-shaped ten- 

 tacles, the lower pair short, small, and with a 

 cylindrical abruptly obtuse shell, with close 

 pressed, gradually enlarging whorls ; the mouth 

 semi-oval, mostly toothed internally; peristome 

 reflexed, and interrupted behind. Jaw lunate, 

 narrow, very slightly striated and crenulated. 



The young shells have a flattened front to the 

 whorls, and a squarish mouth, so that they were mis- 

 taken by some of the older conchologists for Trochi; 

 the older whorls are more convex and rounded in 

 front, and the animal does not form the reflexed lip 

 until it has arrived at maturity; consequently, like 

 the Clausilia among land shells, and the Strombi 



