218 HELICID^E. 



SHELL depressed-convex, thin ; epidermis light horn- 

 color ; whorls less than four, with numerous, delicate, 

 oblique striae ; suture distinct, not much impressed ; 

 umbilicus large, showing all the volutions ; aperture 

 rounded, transverse ; lip thin, acute. 



Greatest transverse diameter less than one-fourth of 

 an inch. 



GEOGRAPHICAL DISTRIBUTION. Inhabits the Western 

 States, is common in Ohio, and particularly abundant 

 near Cincinnati, " in low bottom-lands, near the margins 

 of running streams." It is also abundant in Massachu- 

 setts, near Boston, and in Vermont. 



REMARKS. This species bears a very strong resem- 

 blance, in general aspect, to H. perspectiva, Say, with the 

 immature shells of which it is very commonly confounded. 

 It needs some attention to separate the two ; but when 

 the present species is once noticed, it cannot fail to be 

 considered very distinct. Its discriminative characters, 

 as compared with the former species, are as follows. 

 The mature shell is smaller, and has generally rather 

 less, and never more, than four whorls ; and in shells of 

 the same size the number of volutions is less. It is 

 thinner and more delicate ; its color is lighter ; its strige 

 of increase are more numerous, more oblique, much 

 finer, and less prominent ; its suture is less deeply im- 

 pressed ; its spire is more convex, and its umbilicus less 

 expanded. The character of the epidermis is the same 

 in both. The lustre of the epidermis resembles that of 

 satin. 



