212 Descriptions of New Species of Pupadce. 



ascending at the aperture, rapidly expanding, with an external 

 whitish callus, between which and the peristome there is a deep 

 constriction ; aperture small, nearly circular, with three obtuse 

 teeth of about equal size, one on the parietal margin, one on 

 the columellar margin, and the third far within and at the base 

 of aperture ; peristome sub-reflected, the margins j oined by a 

 thin callus. 



Length .13 inch ; breadth .06 inch. 



Distribution. — Drift on the Missouri River, near Fort Ber- 

 thold. 



Remarks. — This species bears some resemblance in form to 

 P. badia, it resembles more closely P. bigranata of Europe, 

 but differs from both these species in the characters of the 

 aperture, and more especially in the presence of a tooth at the 

 base of the aperture. 



W. G. Binney mentions this by name simply in a list of shells 

 in F. V. Hayden's Report to Lieut G. Warren in the work 

 quoted above. As it has not been mentioned in any of his sub- 

 sequent writings, we infer that he relinquished his views as to 

 its novelty. 



