& MEAS, 
"íi 
inhabiting the United States. 359 
» 
Helix clausa, Lamarck. Anim. sans mN 2d edit., 
VIII, 114. 
Triodopsis clausa, Rafinesque. 
DESCRIPTION. 
Animal. Dark bluish slate color, head and ten- 
taculæ almost black; superior tentaculæ. long and 
slender; foot narrow, in length more than twice the 
diameter of the shell, terminating ‘in an acute angle. 
Shell depressed ; epidermis brownish horn color, 
sometimes with very fine, hair-like projections; 
whorls five, with very minute transverse striw; su- 
ture not much impressed ; aperture three-lobed, very 
much contracted ; lip white, narrow, reflected, with 
a deep groove or indentation behind the reflection, 
contracting the opening so.that the outer edge of the 
lip does. not project beyond the surface of the whorl ; 
on the inner margin of the lip are two acute teeth, 
with the points directed inwards, one near the base, 
the other midway between that and the junction of 
the lip with the body-whorl, with a circular sinus 
between them, forming one of the lobes of the aper- 
ture; pillar-lip with a long, areuated, white tooth ; 
umbilicus covered, its place considerably impressed. 
. Greatest transverse diameter, one-third of an inch ; 
ordinary size, less. 
Groanapnican Distristuion. Inhabits the. West- 
ern States, on the borders of the Ohio and Mississippi 
rivers; it was noticed by Mr. Say in Missouri, and 
by others in North Carolina and Arkansas. 
Remarks. This species is not likely to be mista- 
ken for any other. It resembles a variety of Hexix 
