OF THE UNITED STATES. 



153 



This shell is found on the banks of the Mississip- 

 pi in moist places. It very much resembles H. triden- 

 tata but is destitute of umbilicus, has a rugose epider- 

 mis, and is much larger. It is still more closely allied 

 to appressus but its superior magnitude, teeth and 

 epidermal vesture, distinguish it from that species. 

 Specimens have subsequently been found by Dr. 

 Thomas M'Euen near the falls of Niagara. 



4. H. *inflecta. Spire convex ; volutions ^we t 

 wrinkled across; suture not profoundly impressed ; 

 aperture strait; labrum reflected, bidentate, teeth se- 

 parated by a profound sinus, the superior teeth in- 

 flected, behind the lip a profound groove, which ab- 

 rubtly contracts the aperture in that part, so that 

 although the lip is reflected, yet its edge is not more 

 prominent than the general exterior surface of the 

 body whorl, at base the lip is adpressed and covers 

 the umbilicus ; labrum with a large prominent ob- 

 lique lamelliform tooth; umbilicus closed. 



Greatest transverse diameter nearly 9-20 of an 

 inch. 



Inhabits Lower Missouri. 



The teeth of the labrum somewhat resemble those 

 oftridentata ; but in the form of the groove behind 

 the labrum, and the pillar tooth, it resembles H. hir- 

 suta, several specimens were found, but all dead 

 shells, and destitute of their epidermis. 



