273 



Sect. II. OPERCULATED. (Operculata.) 



The mantle edge separate from the back of the neck 

 of the animal, leaving an open pulmonary chamber ; 

 tentacles two, elongate, contractile, with the eyes on 

 the outer side of their base. They are all dioscious, 

 terrestrial, and furnished with a distinct operculum. 



It contains only a single British genus, the type of 

 a large family. 



Fam. 1. CYCLOSTOMIME. 



Animal with a broad foot, a central spiral body, 

 enveloped in a simple edged mantle, which is 

 covered with an ovate spiral shell, with a 

 roundish mouth, and furnished with a spiral 

 operculum. 



CTCLOSTOMA ELEGAKS. 



4 Showing the under side of the foot, divided into two parts. 



5 The operculum. 



N 5 



