OP CONCHOLOGY. 307 



7. Leucochila contracta, Say. 



Plate 15, figure 16. 



Subconical ; whorls 6, with moderately impressed sutures ; 

 aperture small, trigonal, the margin continuous, reflected, much 

 thickened within, the throat nearly filled by the large teeth 

 which include an irregular one on the parietal margin, project- 

 ing into the aperture and concave on its right side, a tubercle on 

 the umbilical side and another in the base, and a raised tooth on 

 the outer margin of the lip ; base keeled, minutely perforate. 

 Light horn color. 



Length 2*5, diam. 1-3 mill. 



Maine to Iowa and southward to Florida and Texas. 



8. Leucochila rupicola, Say. 



Plate 15, figure 17. 



Narrow, cylindrically fusiform, apex obtuse ; whorls 6, slightly 

 convex ; aperture small, oval, the lip thickened within and widely 

 reflected : teeth five in number, namely, one on the parietal wall, 

 large and emarginate (sometimes deeply), a conical one, some- 

 times divided, on the umbilical margin, the third at the base, the 

 fourth on the outer lip, and the fifth deeply seated within the 

 outer lip ; frequently all the teeth but the first two are wanting ; 

 umbilicus minutely perforate. Brownish. 



Length 2-5, diam. 1-2 mill. 



Pennsylvania to Florida, Arkansas. 



9. Leucochila corticaria, Say. 



Plate 15, figure 18. 



Subcylindrical, apex obtuse, whorls five, convex, with well- 

 impressed sutures ; aperture small, rounded, with white, re- 

 flected lip, on the' parietal wall is a small tooth, or rarely two 

 teeth, and the umbilical side of the lip is also partially dentate, 

 although occasionally both teeth are wanting. Substance thin 

 and translucent, whitish. 



Length 2-5, diam. 1-3 mill. 



Northern, Middle and Western States ; Mississippi. 



