inhabiting the United States. 383 
curved tooth, placed obliquely in the aperture; um- 
bilicus open, deep; base women strice converging 
into the umbilicus. 
Greatest transverse diameter three rem of an 
inch ; common size less than half an inch. 
Chiscii sea ‘Distrisution. — Inhabits all the 
States. Common in forests in - interior, less fre- 
quent near the sea-coast. 
Remarks. "This common and well-marked shell 
varies considerably in size. In the fertile sections 
of the Western States it attains its largest diameter ; : 
in Vermont it usually measures about. half an inch, 
and on the sandy soil óf 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 contracted, the 
spire more prominent, and the whorls comprise more 
than five volutions. But the most remarkable variety 
is that which Say considered distinct enough to form 
a séparate species, under the name of Herrx fallar. 
In this, the spire is more elevated, and sometimes has 
six full volutions. There is a deep groove behind the 
lip contracting the aperture; the lip'is widely re- 
flected and directed inwards, forming a basin-shaped 
mouth ; the upper labial tooth is broader, ‘sometimes 
bifid and even trifid, and very much inflected; the 
columellar tooth extends quite to the base of the 
shell, and unites with the extremity of the lip; the 
