56 HELICID^. 



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, some-what diminished by the intrusion of 

 the penultimate -whorl. Peristome thin and acute, the 

 columellar margin a little reflected. Axis imperforate. 

 Greatest transverse diameter nearly one-fourth of an 

 inch. 



Geographical Distribution. Tliis species -was first 

 noticed in the United States by Mr. Say, near Coldwar 

 ter Lake, North--westem 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 hkewise 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, 



