v*» 



inhabiting the United States, 



489 



E 



contracted by the lip, the plane of the aperture making 

 a considerable angle with the plane of the base of the 

 shell : pillar lip^ with a prominent, white, tooth-hke 

 process placed obliquely to the axis of the shell : lipy 

 white, widely reflected, and sometimes grooved ; exterior 

 of the reflected lip yellowish: umbilicus QyA^\\Ai\l\g only 

 one volution, partially covered by the reflected lip where 

 it unites with the base of the shell. 



J- 



Extreme transverse diameter three fourths of an inch. 



Geographical distribution. Inhabits all the States 

 from New York to Missouri, and from North Carolina to 

 Arkansas. It is very common in the country bordering 

 on the Ohio and Mississippi rivers, and though sometimes 

 found, is rare in the New Eng-land States. 



Kemarks. This species bears a strong resemblance 

 to H. alholabrisy with which it is sometimes confounded. 

 It has, however, striking specific characters, which are 

 never wanting, and which will enable one always to dis- 

 tinguish it. These are, the partially closed umbilicus, 

 and the tooth on the pillar lip. The yellow color on the 

 posterior part of the reflected lip is also a very constant 

 character ) this is derived from the mantle of the animal, 

 which^ in a state of rest, frequently overlaps the margin 

 of the anertnrfi. It is a smaller shell than Helix albo- 



aperture 



labris, and more convex, sometimes being even globose, 

 and the plane of the aperture makes a much larger angle 

 With the plane of the base of the shell. 



It varies considerably in appearance. Some individuals 

 never reach half the standard size of the species. It is 

 more or less globose, has the umbilicus sometimes cover- 

 ed, and at other times is destitute of the teeth. The 

 animal, though usually yellowish, I have noticed to be in 

 a few cases blackish. It is probable that the color of the 



VOL. I. PART IV. 



63 



