HELIX. 421 



edged with brown, widely reflected, with two projecting teeth on 

 the inner margin, the one near its jnnction with the body whorl 

 acnte and prominent, the other on the basal portion, long, lamellar, 

 and but little ijromincnt ; imrictal wall with a very 



. . Fis. 679. 



prominent, white, curved tooth, projectmg nearly 

 perpendicularly from the shell, and forming one 

 boundary of the aperture ; umbilicus covered with 

 a white callus, the continuation of the reflected 

 peristome ; base convex. Greater diameter twenty- 

 one, lesser, eighteen, height ten millimetres. 



From Canada to Georgia, through Eastern North 

 America. Also in the post-pleiocene of the Missis- 

 sipj>i Valley. 



Animal of a uniform, blackish, slate color over 



H. palUata. 



the whole surface ; foot narrow, in length double 

 the diameter of the shell, and terminating in an acute point ; eye- 

 peduncles one third of an inch long ; eyes not distinguishable from 

 the general color. 



The nature of the epidermis and sculpturing are the only con- 

 stant specific characters which distinguish H. palliata from H. 

 obstricta. In the former the epidermis has " numerous minute tu- 

 berculous acute prominences"; the strife are close together, and 

 somewhat irregular in development. In the typical form the whorls 

 are convex, Avith a well-impressed suture ; the last whorl is obtusely 

 angulated in front of, but not Ijchind the aperture. 



The species varies, in the form of the whorls and extent of the 

 angulation of the periphery, as follows : — 



Var. i3, — Whorls flattened above, slightly exserted, the last more 

 sharply angulated in front of the aperture, with the striae, especially 

 behind the aperture, more distinctly defined. Greater diameter 

 twenty-two, lesser nineteen and a half, height eight and a half mill- 

 imetres (five whorls). Kentucky and Tennessee. 



Var. y. — Whorls planulate above, and so exserted as to show 

 the carinated edges of all excepting the apical whorls, the last 

 whorl with an acute projecting carina continued to the back of the 

 aperture ; the umbilicus not always entirely covered by the reflected 

 lip. Greater diameter twenty-one and a half, lesser eighteen and 

 a half, height seven millimetres (five whorls). Tennessee. 



