Description of Eight new Spedes of Shells. 109 



however approaches most nearly to the Crepidula convexa, and in- 

 deed it is with some doubt that I separate it. But the two sides are 

 ahke in their curvature, the outside smooth, the cyathus diapha- 

 nous and not so deeply situated, the color usually much darker, 

 and the apex straight. Besides this, its habitat seems different, 

 our species being found chnging to the Ostrea Canadensis, while 

 the C. convexa, according to Dr. Gould, is found upon sea-weed 

 and stones at the roots of sea-weed. 



Genus Carychium. — Leach, 

 C. exile. Pi. 1, fig. 5, 



C. testa ovato-conica, valde elevata, sub-perforata, diaphana, 

 albida, longitudinaliter striata; spira obtusa; anfractibus senis, 

 convexis ; suturis impressis ; apertura elliptica, Integra, dentibus 

 tribus ; labio valde reflexo. 



Shell ovately conical, much elevated, sub-perforate, diapha- 

 nous, whitish, longitudinally striate ; spire obtuse ; whorls six, 

 convex ; sutures impressed ; mouth elliptical, entire, with three 

 teeth; lip much refiexed. 



Length -075. Breadth -025 of an inch. 



Hab. Under dead leaves and mould,^on the Wissahiccon creek, 

 near Philadelphia. Cabinet of I. Lea. 



Remarks. — This beautiful little shell bears a strong resem- 

 blance to the Pupa exigua of Say, and it is with some doubt 

 that I propose it. The chief points in which it differs from that 

 shell are the following. The lip is continuous round the mouth, 

 and not interrupted by the last whorl, as is the case with the 

 Pupa, thus being a true Carychium ; the lip is flattened, the 

 number of whorls is greater, there is a tooth on the outer lip, the 

 size is smaller, and the shape more elongated. It also nearly ap- 

 proaches the Carychium, minimum, Leach, an European shell, 

 but may be easily distinguished by its strise, shape, number of 

 whorls, perforation, and teeth. The tooth on the outer lip is very 

 variable, being sometimes almost obsolete and sometimes larger 

 than those on the inner one. Of the two teeth on the inner lip, 

 one is placed at the middle, and the other very near the base of 

 the mouth, and so far in as to be almost invisible on a front view. 

 The mouth is -02 of an inch in length. It appears to be the 

 only true Carychium yet found in the United States, its small 

 perforation, hardly amounting to an umbilicus, not being suffi- 

 cient to separate it from that genus. In its shape and mouth it 

 strongly resembles the genus Clausilia, but it wants the clausum, 



