COLIMACEA. MOLLUSCA. HELIX. 179 



Shell small, orbicular, very much depressed, almost discoidal, 

 of a uniform reddish horn-color ; whorls four, flattened above 

 and rounded below, separated by a well-defined suture, delicately 

 wrinkled by the elevated and sharp lines of growth, and in all im- 

 mature stages presenting a sharpened or carinated edge at the 

 circumference ; aperture rounded, declining, somewhat broader 

 than high ; lip simple and thin ; lower surface rendered cup- 

 shaped by a broad and deep umbilicus, whose diameter is nearly 

 that of the outer volution. Diameter about one fourth of an inch. 



The animal has the tentacula bluish-black ; margin, and pos- 

 terior part of foot, white. Foot transparent, less than twice the 

 diameter of the shell in length ; terminating acutely. 



Found abundantly in all parts of this State, about old stumps, 

 and under the bark of decaying logs. 



The cup-shaped base, and beautifully raised lines of growth, suf- 

 ficiently designate this shell. Its form is like that of H. rotunduta of 

 Europe, which, however, is checkered by darker bars, like our H. 

 alternuta. 



This is the shell, which, till recently, has been regarded as the II. 

 pcrspecliva of Say. Several gentlemen in Ohio, where both species 

 are found, have for some years discriminated the two shells ; and in 

 January, 1839, Mr. J. G. Anthony communicated to the Boston So- 

 ciety of Natural History a description of this species. After mature 

 examination, conchologists have become satisfied that the Massachu- 

 setts shell is the H. striatella, and that H. perspectiva is not found in 

 this region. The differences are, that H. striatella is altogether a 

 more delicate shell in structure and marking, the number of whorls 

 is one less, the color is lighter, and the shell smaller ; the sharp ex- 

 ternal edge is also more conspicuous, and, looking into the throat, we 

 do not find the tooth-like thickening which exists within the lower 

 margin of H. perspectiva. Mr. Anthony also observes, that it is found 

 in low lands, near running streams, and never about rotten logs, the 

 common residence of H. perspectiva. This, however, does not accord 

 with its habits in Massachusetts. 



Helix linea'ta. 



Shell small, discoidal., green ; ichorls four, icitli fine, elevated, 

 parallel, revolving lines ; aperture narrow, semi-lunar ; lip simple ; 



