35 



the whorls are lower; tliere is an umbilicus about .03 inch in diam- 

 eter extending to the apex ; the aperture is smaller, and the last 

 whorl is much flattened beneath. 



Greatest breadth .49 inch ; least breadth .42 inch ; height .25 

 inch. 



Hemx ambigua. a single individual occurs, which is like H. 

 similis, but smaller ; with the spire more elevated, the columella 

 less oblique, and the anterior part of the lip more directly trans- 

 verse, with a smaller umbilicus. The suture is deeper than in 

 H. similis or in H. arboreoidcs , between which this shell is in most 

 characters intermediate. Having but one specimen, I do not 

 regard the species as fully established. 



Greatest breadth .40 inch ; least breadth .42 inch ; height .25 

 inch. 



Helix Anthoniana. Shell conic ; whitish ; with a thin pale 

 brown epidermis ; with excessively fine striae of growth ; spire with 

 rather convex outlines, well elevated ; apex subacute ; whorls seven, 

 quite convex, with a deep suture ; aperture sublunate ; lip sharp, a 

 little reflected in the columellar portion ; umbilicus narrow. 



Mean divergence 98° ; greatest breadth .42 inch ; least breadth 

 .375 inch ; height .35 inch. 



Helix brevis. Shell subdiscoidal ; whitish ; smooth and .shin- 

 ing ; spire convex, but little elevated ; apex obtuse ; whorls more 

 than four, slightly convex, short, with a moderately impressed su- 

 ture; last whorl a little flattened beneath; aperture lunate; lip thin 

 and sharp; umbilicus rather small. 



Greatest breadth .15 inch; least breadth .13 inch; height .04 

 inch. 



Helix simulans. Species like H. fulva Mull., (H. chersina 

 Say,) and formerly supposed to be identical with that species. It 

 is chiefly distinguished by numerous microscopic impressed spiral 

 lines; the whorls are less by one, viz. four and two-thirds, and the 

 spire is less elevated, with 10° more divergence. It is of a glossy 

 brown, deeper than in H. fulva. 



Mean divergence 92° ; greatest breadth .11 inch; least breadth 

 .09 inch ; height .08 inch. 



Helix fuscula. Shell subconic ; brown ; with fine stria) of 

 growth; spire well elevated convexly; apex subacute ; whorls four, 

 quite convex, with a deep structure ; aperture sublunate ; lip sharp 

 and thin : last whorl verv convex around the small umbilicus. 



