MOLLUSC A OR UNIVALVES. 169 



snails having been some years in a cabinet, and 

 on the shells being put into warm water to be 

 washed the animals made their appearance alive. 



These mollusca have the power of repairing 

 their bodies when injured as well as their 

 shells : a horn, or even the whole head, if cut 

 off, will be reproduced, the animal keeping 

 within its shell until grown again. The head, 

 however, requires some months to be replaced. 



The Helix pomatia is said by some authors 

 to have been introduced into this country from 

 abroad, but others suppose it to be indigenous. 

 It is almost peculiar to chalky and gravelly soils. 

 The eggs of this species are globular, covered 

 with a white opaque skin, and are about two 

 and a half lines in diameter.* 



Mr. Gray mentions having seen a specimen 

 of a Helix aspersa curiously deformed by the 

 obstruction of a young shell of the same spe- 

 cies. The young specimen is attached to the 

 spire, to which it had doubtless fixed itself 

 during the dry season ; and not waking from 

 its torpor so early as its older companion, the 



* Turton. 



