188 HELICIDJE. 



the same individual. I have had occasion to notice con- 

 siderable numbers of the animal of Polygyra septem- 

 volva, Say, but have not observed any fact which would 

 tend to confirm such an opinion. On the contrary, it 

 has appeared to me that they were analogous in all 

 respects to the animals of the genus Helix. 



This shell is peculiar for the complicated form of its 

 aperture, which bears a considerable resemblance to the 

 human ear. In mature individuals the lip is very much 

 projected, the folds within the aperture are prominent, 

 and the aperture greatly contracted. The laminated 

 folds within are marked by corresponding depressions 

 externally, behind the reflection of the lip. At different 

 periods of growth the aperture differs very much in 

 appearance, and has led naturalists into error. When 

 the lip is just beginning to be formed, and as yet projects 

 but little, there are two projecting teeth on its inner edge, 

 with a deep sulcus between them ; as these continue to 

 grow, they assume more and more the appearance of 

 lamellar folds, the lower one of which, when viewed on a 

 line perpendicular to the base of the shell, hides the 

 other. The columellar fold, at the same early period, 

 appears more like an independent tooth, to each extrem- 

 ity of which the lip is connected. It is this variety 

 which Mr. Say described as a distinct species, under the 

 name of Polygyra avara. This opinion I derive not so 

 much from his descriptions as from the examination of 

 original specimens collected and labelled by him, now in 

 my possession. I have specimens of the mature shell 



