1817.1 GENUS HELIX 123 



d. A lateral view of the flower without the 

 calyx. 



e. A front view of the same. 



f. One of the stamina exhibiting the forked 

 filament. 



Descriptions of new species of Land and Fresh Water 

 Shells of the United States, By Thomas Sai/. Head 

 October 28, 1817. 



Genus HELIX. Linn. Lam, 



For the generic characters, see p. 17 of this volurrie. 



SPECIES. 



1. I£, thyroidus. Shell thin, fragile, convex, umbili- 

 cate; whorls live, obtusely wrinkled, or rather with equi- 

 distant, gradually elevated^ obtuse lines, and spirally stri- 

 ate with minute, impressed lines; lip widely reflected, 

 white and flat before, partially concealing the umbilicus; 

 pillar lip furnished with a very oblique tooth. 



Breadth four fifths to nine tenths of an inch. 



This species very much resembles H. Albolabris of 

 Nicholson's Encyc. Amer. Ed. but is umbilicated, and 

 toothed on the pillar lip. It is much less common. This 

 shell was indicated in the American Edition of Nicholson's 

 Encyclopaedia; but its characters were not laid down. 



2. /T. minuta, aS/z^// rather thick; j/^zyd" convex, little 

 elevated, with three volutions; suture well defined, im- 

 pressed; whorls obtusely wrinkled across; aperture nearly 



