56 HELICIDJE. 



mantle extends from under the shell, over the back and 

 neck to the base of the tentacles, but is unattached and 

 free ; from the right side of the mantle posteriorly, there 

 arises a tongue-shaped process, which is reflected back 

 upon the shell, and reaches to the spire. Respiratory 

 foramen in the posterior part of the mantle. 



SHELL. Globose-discoid, thin, fragile, transparent, 

 shining ; whorls two and a half to three, scarcely convex, 

 with very minute lines of increase, the last whorl large, 

 and much expanded. Suture not much impressed, some- 

 times with an impressed line revolving near it ; aperture 

 large, sub-ovate, somewhat diminished by the intrusion of 

 the penultimate whorl. Peristome thin and acute, the 

 coluinellar margin a little reflected. Axis imperforate. 

 Greatest transverse diameter nearly one-fourth of an 

 inch. 



GEOGRAPHICAL DISTRIBUTION. This species was first 

 noticed in the United States by Mr. Say, near Colclwa- 

 ter Lake, North-western Territory, in latitude 48 45' 

 North, and between that point and Lake Superior it fre- 

 quently occurred. Prof. C. B. Adams has recently dis- 

 covered it on Rogers' rock, an island at the north-eastern 

 extremity of Lake George, in latitude 43 north. It 

 has likewise been found in considerable numbers in the 

 vicinity of Portland, by Dr. J. W. Mighels ; it is said to 

 occur also, in the north-eastern part of Maine. 



REMARKS. It is found under stones, decaying leaves, 



