HELIX. 243 



Greatest transverse diameter more than one-fifth of an 

 inch. 



Geographical Distribution. Inhabits the Northern, 

 North-eastern, Middle, and Western States, and is proba- 

 bly a wide-spread species, i^ 



Remarks. This shell is found in the same situations 

 as Helix arhorea, Say, and resembles it very much, par- 

 ticularly on its upper surface. It may be distinguished 

 from it by the outer whorl, which is more spread towards 

 the aperture ; by the impressed, radiating hues, and by 

 the want of an open umbilicus. The whorls, in this spe- 

 cies, usually revolve in such a manner as to leave no 

 opening between them ; but there is an occasional speci- 

 men with a well-formed umbilicus. 



71. HELIX CHERSINA. 



Plate XV IL Figuee 4. 



H. testa minima, conoidea, nitida, tenuissima, pellucida, 

 imperforata; apertura transversa; labro simplici, acuto ; 

 basi convexo. 



SYNONYMS AND KEFEKENCES. 



Helix chersina^ Sat, Joura. Acrid. IL 156. 



Exped. St. Peters, IL 258. 

 BiNNEY, Boston Journ. Nat. Hist. III. 416, pi. 26. f. 2. 

 Gould, Inverlebrata, 185, f. 105. 



Adams, Vermont Mollusea, 12; Sillim. Journ. XL. 273. 

 De Kay, Nat. Hist. New York, 44, pi. 35, f. 338. 



DESCRIPTION. 



Animal bluish-black upon the head, neck, and tenta- 



