252 HELICID^. 



adopt Draparnaud's specific and significant name of mar- 

 ginata. It is more than probable that Linne knew both 

 this species and P. umbilicata, but did not distinguish 

 one from the other. The present species appears, how- 

 ever, to be the Helix muscorum of Miiller, who pointed 

 out the difiference between his and Linne' s species of the 

 same name. This is the Turbo chrysalis of Turton, 



Genus VII. VERTI'GO^ MiiUer. PI. VII. f. 6, 7, 8. 



Body rather short, always containable mthin the shell : 

 tentacles 2 only, scarcely at aU inflated at their extremities : 

 foot short. 



Shell subcylindiical or fusiform, thin, and glossy : whorls 

 compact, the last considerably exceeding the others in size : 

 spire short, sometimes reversed : mouth semioval or semicircular, 

 usually furnished with several teeth, in which case the outer 

 lip is contracted : umhiliciis scarcely perceptible, or consisting 

 of an obhque and narrow chink. 



The members of this genus are miniature forms of 

 Pupa ; and their habits are the same, except that these 

 are more retired and avoid the sun's rays more than 

 some species of Pupa. But the difierence between them 

 does not consist in size alone. The animal of Vertigo, 

 instead of having, like that of Pupa, four tentacles, has 

 only two, and is quite destitute of the lower pair. I have 

 satisfied myself, by a careful examination of many living- 

 specimens, that not the slightest rudiment or vestige exists 

 of a second pair of tentacles in several species of Vertigo , 

 although in V.pygmcea and V. jmsilla lines or dark spots 

 are discernible in the places which would be occupied by 

 these tentacles if they were present. Midler was the 

 first to discover the fact of these mollusks being biten- 

 taculate, and founded on it the present genus. Several 



* A turning round. 



