13 



size, exterior, and armature they are so different from the 

 Ohio specimens, yet as I have seen so many intervening 

 varieties, I think this form should be abandoned as a species. 



Notwithstanding all these discrepancies, there is a certain 

 aspect about the shell which enables one to distinguish it 

 without much difficulty. Its ovate form, its very small aper- 

 ture, with the transverse portion so oblique that the inner lip 

 is very short in proportion to the outer one, will serve to de- 

 termine the species with a very small magnifying power. 



Mr. Say found his specimens in Pennsylvania ; it is not in- 

 frequent in the vicinity of Boston, under fallen leaves in shady 

 woods ; Professor Adams found it near Middlebury, Vt. ; Dr. 

 Newcomb found it near Troy, N. Y. ; it is one of the most 

 common species in Ohio, and has been sent me by Dr. Fore- 

 man from near Baltimore, and from Jacksonborough. S. C. 

 Thus, with the exception of P. contracta it has been observed 

 over a wider region than any other species. 



PUPA RUPICOLA. 



Plate XVI. fig. 13. 



P. ovato-conica, glabra, albida, umbilicata ; apice subacuta ; anfractibus sex con- 

 vexis : apertura obliqua, semi-elliptica, dentibus quinque lamellosis armata, quorum 

 unus postice, duo ad columellam, duo ad labium expansum dispositi. 



" Shell dextral, attenuated to an acute apex, white ; suture 

 deeply impressed ; labrum bidentate, superior tooth lamellar, 

 emarginate in the middle, and at the anterior tip uniting with 

 the superior termination of the labrum ; inferior tooth placed 

 on the columella, and extending nearly at a right angle with 

 the preceding ; labrum tridentate, teeth placed somewhat 

 alternately with those of the labium ; inferior tooth situated at 

 the base and immediately beneath the inferior tooth of the la- 

 bium. Length ^ inch." 



About the size of P. corticaria, and considerably resembles 

 that species, but is sufficiently distinguished by the circum- 

 stance of its gradually decreasing in diameter from the body 

 whorl to its tip, and in the character of the mouth it is widely 

 distinct. (SAY, Journ. Acad. Nat. Sc. II. 163.) 



