184 HELICID^. 



and a half to six, crossed obliquely by numerous acute, 

 raised lines ; aperture trilobate, more or less contracted 

 by a groove behind the lip ; lip -white, reflected, its outer 

 contour rounded, furnished on its inner margin with two 

 acute, projecting teeth ; pillar-lip with a white, project- 

 ing, slightly curved tooth placed obliquely m the 

 aperture ; umbihcus open, deep ; base rounded, strias 

 converging into the umbilicus. 



Greatest transverse diameter three-fourths of an inch ; 

 common size less than half an inch. 



GEOGRAPniCAL DISTRIBUTION. Inhabits all the States. 

 Common in forests in the interior, less frequent near the 

 sea-coast. 



Remarks. This common and well-marked shell varies 

 considerably in size. In the fertile sections of the West- 

 ern States, it attains its largest diameter ; in Vermont 

 it usually measures about half an inch, and on the sandy 

 soil of Florida only a fourth of an inch in diameter. It 

 varies also in the characters of the lip and aperture. 

 In specimens from the North-eastern States, the lip is 

 usually narrow, but slightly contracting the aperture, the 

 teeth are but little prominent, and the spire is flattened, 

 comprising less than five whorls. In those from the 

 Western States, the lip is wider, the aperture more con- 

 tracted, the spire more prominent, and the whorls com- 

 prise more than five volutions. But the most remarkable 

 variety is that which Say considered distinct enough to 

 form a separate species, under the name of H. fallax. 



