76 EOCENE MOLLUSCA. 



edges, and costellation of the volutions, in the shape of the aperture, and in the 

 character of the columella ; and I consider it, therefore, as merely a variety. It is a 

 ventricose shell, with a shorter spire, and more convex whorls ; the aperture is longer 

 in proportion, exceeding the spire in length, owing probably to the shell not having 

 attained maturity. The specimen, the only one I have seen, belongs to Mr. D'Urban's 

 collection. 



Size. — Axis 1 inch and 6-10ths; diameter, 1 inch, nearly. 



Localities. — Sconce, Shalcombe, Binstead, Isle of Wight. 



Genus 9th. Pupa.* Lamarck. 1801. 



COCHLODONTA, (sp.), FcrUSSUC. 



Cochlodina, (sp.), Ferussac. 

 Cochlogena, (sp.), F6russac. 



Gen. Char. — Shell cylindrical, elongated, or sub-globose ; apex generally obtuse, 

 sometimes acuminated ; whorls numerous, slowly increasing, the last smaller than the 

 penultimate one ; frequently striated or ribbed ; aperture generally elliptical, some- 

 times sub-quadrate in front, and rounded behind ; peritreme continuous, slightly 

 incrassated and reflected ; outer lip dentated ; teeth variable in number ; one or two 

 plaits on the columella. 



The present genus is one of the dismemberments effected by Lamarck of Bruguiere's 

 genus Helix. The organisation of the animal bears a strong general resemblance to 

 that of the animals of Helix and Bulimus ; and Ferussac has reunited the genus to 

 Helix, in which it is distributed among the sub-genera Cochlodonta, Cochlodina, and 

 Cochlogena. The shell, however, prevents striking dissimilarities, and in the animal, 

 according to M. Deshayes, the same modifications of the generative organs occur 

 which distinguish the animal of Bulimus. The elongated cylindrical form of the spire, 

 the proportion of the last whorl to the penultimate one, and the direction of the 

 aperture which is parallel with the axis, distinguish the shell from Helix ; and it is 

 separated from Bulimus by the numerous and slowly increasing volutions, and by the 

 teeth and folds with which the outer lip and the columella are furnished. It is to 

 Clausilia that it bears the closest resemblance ; but from that genus it is separated as 

 well by the aperture as by the absence of the clausium, a character which, however, 

 can seldom be available to the Palaeontologist. 



In the animals of several of the smaller species the peduncles only exist, the ten- 

 tacles becoming obsolete. Some of these species are sinistral and hyaline, and form 

 Miiller's genus Vertigo. The animal, however, exactly resembles Pupa in everything 

 but the absence of the tentacles, and, inasmuch as their disappearance is very gradual 



* Etym., from a supposed resemblance to the Pupa or Chrysalis of some insects. 



