HELICID.E. 123 



II. Body elongate ; mantle thin, with a thickened edge, 

 only lining the inside of an external shell, which 

 it forms or rather moulds on its surface. 



C. Body with two longitudinal grooves, from the front 

 of the mantle to the head ; lips subcylindrical, re- 

 tractile. (Testacellina.) 



3. Testacella Cuv. (Testacelle.) 

 Body elongate, tapering in front, with two diverging 

 grooves from the front of the mantle, extending 

 to the head ; mantle small, covered with an ear- 

 shaped shell, with a very short spire, which is placed 

 on the hinder part of the body. The mouth of the 

 shell is very large, the outer lip thin, with a slight 

 notch at the hinder end. 



Faure Bigu^t, who first discovered the animal, 

 called it Testacellus ; Draparnaud and Cuvier have 

 changed the name to Testacella. 



The animals, according to the observations of M. 

 Ferussac, have a peculiar mantle (or rather ap- 

 pendage of the mantle), which is simply gelatinous, con- 

 tractile, and habitually hidden under the shell, divided 

 into several lobes, and susceptible of an extraordinary 

 development, so as to envelope the whole of the con- 

 tracted body of the animal, and thus protect it from 

 extreme drought. 



The animals live for the greater part of their life in 

 holes under ground, only coming to the surface to 

 change their locality ; and they remain buried during 

 the cold or very dry weather. It is this power of pro- 

 tecting themselves from the effect of sudden changes of 

 temperature, there is little doubt, that has allowed them 

 to adapt themselves with such facility to our climate. 

 g2 



