58 



thnmberland ; Limax Sowerbii abundant about Lon- 

 don and in Ireland; and Limax gagates chiefly in 

 Ireland. 



Testacella haliotoidea, a solitary species interraediate 

 between the slugs and snails, and bearing a shell at the 

 extremity of its back, is carniverous in its habits. It 

 has not been found north of London. 



Helicidje. 



This large family of British snails are furnished, for 

 the most part, with spiral shells, which are, without an 

 exception devoid of an operculum. However, instead 

 of this appendage, the animal has the power of closing 

 the aperture, during the cold weather of winter and the 

 hot dry weather of summer, by a membranaceous or 

 mucous covering, which is perforated with holes to en- 

 able the animal to breathe. The snails have four ten- 

 tacles, in the upper pair of which, at the extremity, the 

 eyes are situated. 



VlTRINA. 



Shell pellucid, fragile, thin, oblong, somewhat de- 

 pressed, subglobular, and glossy in appearance. Aper- 

 ture large, rounded, lunate, peristome, or margin of the 

 outer lip, thin. Three rapidly increasing whorl*. 



The animal is very large for the dimensions of the 

 shell, elongate, lanceolate. Of the four tentacles, the 

 inferior ones are short. The mantle is large, thick, and 

 covers a portion of the shell. 



