48 AMERICAN JOURNAL 



XOLOTREMA, Rafinesque. 



There are but five species known to belong to this section of 

 the Helices ; characterized by a lamellar tooth on the base of 

 the aperture, and a covered umbilicus. We first indicated its 

 generic value, and gave a list of species belonging to it, in the 

 American Journal of Conchology, p. 81, 1865. These shells in- 

 habit the middle region of the United States rather sparingly, 

 being nowhere very numerous. There are two groups of species, 

 two of them being somewhat rounded trochiform, while the other 

 three are depressed, and generally furnished with an additional 

 tooth on the upper part of the labrum, making the aperture tri- 

 dentate. 



* Shell elevated. 

 1. Xolotrema elevata, Say. 



Plate 9, figure 1 



Shell convexly conical, thick, finely obliquely striated ; spire 

 elevated, with a well-impressed suture ; whorls nearly seven, 

 convex, slowly increasing, the body large and well rounded; 

 aperture somewhat triangular, contracted by the lip, which is 

 thickened, but not very broadly reflected, and covers the umbili- 

 cus ; a long lamellar tooth occupies nearly the whole basal part 

 of the lip, and the pillar lip is furnished with a stout tooth, curv- 

 ing inwards above; the extremities of the labrum frequently 

 connected by a well-defined callus. Yellowish horn color. 



Diam. 23, height 16 mill. 



From Western New York to West Virginia, and westward to 

 Missouri. 



Mr. W. G. Binncy received two specimens, collected by the 

 late Major Kennicott in Wisconsin, which were remarkable from 

 having each a brown band revolving upon its periphery. 



2. Xolotrema Clarkii, Lea. 



Plate 9, figure 2. 



Shell globosely conical, moderately thick, finely striated ; 

 spire obtusely conical, suture moderate ; whorls seven, convex, 

 slowly increasing, the body well rounded ; aperture subtriangu- 

 lar, the lip reflected and thickened, entirely covering the urn- 



