37 



aperture ; volutions six, wrinkled ; spire convex ; aperture sublu- 

 nate, narrower beneath ; within, a prominent tooth near the base, 

 distant from the margin ; labrum simple ; umbilicus rather small, 

 orbicular, profound ; region of the umbilicus indented. 



Greatest breadth more than one-fifth of an inch. Inhabits 

 Pennsylvania. 



I found a few specimens of this shell on the farm of my friend 

 Mr. Reuben Haines, at Germantown. 



With the exception of the size and the armature of the throat, 

 it is somewhat of the habit of H. ligera, JVob.; but the opacity of 

 the body whorl near the aperture, is much more remarkable. 

 These characters, combined with that of the tooth, will readily 

 •distinguish this species from any other. 



PoLYGYRA FATIGIATA. — Shell convcx beneath, nearly plane 

 above, the spire being hardly perceptibly elevated ; whorls a little 

 ■over six, compressed, acutely carinated, crossed by numerous 

 raised, equidistant lines, which form grooves between them ; 

 superior surface not at all convex ; aperture subreniform ; labrum 

 reflected, regularly arctuated, describing two-thirds of a circle ; 

 within two-toothed, lower tooth conic obtuse, superior tooth com- 

 pressed, transverse, placed further within the aperture than the 

 inner one, from which it is separated by a wide and deep and 

 obvious sinus ; labrum with a very profound duplicature, which 

 has a concave surface, but with no emargination near its acute 

 tip ; beneath exhibiting only two volutions, without any distinct 

 groove on the external one near the suture ; beneath the carina 

 the elevated lines are obsolete. 



Greatest breadth seven-twentieths of an inch. 



Found by Mr. Lesueur in the vicinity of New Harmony. It is 

 very closely allied to that species which I described under the 

 name of plicata; the character of the mouth is very similar, but 

 in that shell, such is the situation and form of the teeth of the 

 labrum, that at first view they do not seem to be separated by a 

 remarkable sinus, and the inferior tooth is compressed and larger 

 than the other ; the duplicature of its labium is emarginate near 

 the tip. The present species is also larger, carinated, and the 

 •elevated lines are obsolete below the carina. 



Helicina occulta. — Carinated ; carina almost concealed on 

 the spire, and nearly obsolete on the body whorl ; whorls about 



