OF THE UNITED STATES. l5i 



2. H. *appressa. Shell depressed, brownish horn 

 colour ; whmis five, depressed, forming an angle on 

 the external one, more acute near the superior angle 

 of the labrum, with numerous transverse, elevated, 

 equidistant lines, with interstitial grooves ; umbili- 

 cus covered over with calcareous matter, but con- 

 cave within ; aperture moderate ; labrum dilated, 

 reflected, white, margined with brownish ; near the 

 base, appressed to the body whorl, and covering the 

 umbilicus ; a slight projecting dentiform angle on the 

 inner middle ; labrum with a strong, prominent, ob- 

 lique, compressed, white tooth, which gradually 

 slopes and becomes obsolete towards the umbilicus. 



Var. a. Labrum with two projecting angles. 



Breadth, three-fifths of an inch. 



Animal— -foot pale ; neck above and each side 

 blackish. 



Inhabits the banks of the Ohio and Missouri. 



This species is very common on the banks of the 

 Ohio below Galiopolis: I also found it near Council 

 Bluff. It very much resembles H tridentata, but 

 the umbilicus is covered over; the outer lip at base 

 is flattened upon the shell; and there is but a single 

 angle upon it. In Lister's conch, pi, 93, fig. 93, is 

 the representation of a shell, which is most probably 

 intended for this species. Lister's figure is quoted 

 in the books, for H. punctata, but as the figure of a 

 different species (Bom mus. pi. 14, fig. 17 and 18) 



