158 HELICID^E. 



inspection of the aperture shows a different structure. 

 The aperture is very narrow, and nearly closed by an 

 elongated lamina on the pillar margin, which is dilated, 

 or rather bifurcated, at its outer end. The outer lip is 

 narrow, reflexed, and has an emargination near its upper 

 junction, which is divided into two portions by a toothlike* 

 process ; and alongside of the lip, but nearly concealed 

 within the fauces, is another lamina, leaving a mere fis- 

 sure for the exit of the animal. 

 Diameter one-fourth of an inch. 



GEOGRAPHICAL DISTRIBUTION. Brought by Mr. Bartr 

 lett from Tennessee. 



REMARKS. This is another interesting example, 

 among several recently furnished by an exploration of 

 the South-western States, of the gradual transition, by 

 almost imperceptible modifications, from one species to 

 another, and of the many changes which are wrought by 

 the varied combination of a few characters signalizing a 

 group. However great its general resemblance to H. 

 hirsuta may be, this species is decidedly characterized 

 by the singular, jaw-like plate within the fauces. [G.] 



