North American Helices. 361 



somewhat regular impressions or indentations with ridges be- 

 tween, causing it to look as if covered with scales ; where 

 these are not apparent it is marked with oblique wrinkles. 



Transverse diameter one inch and a quarter. 



Geographical Distribution. The only specimen I have 

 seen, belonging to the cabinet of Andrew Belknap, Esq., was 

 taken near St. Diego, California. 



Remarks. This beautiful and well defined species is unlike 

 any other which I have noticed ; and no description has been 

 met with, which corresponds with it. It resembles in its gen- 

 eral appearance. Helix Dupetitthouarsi of Deshayes, (Guerin. 

 Mag. de Zool. 1841, pi. 30,) but it is destitute of an umbilical 

 opening which in that species is large. The singular indenta- 

 tions of the surface resemble very exactly the impressions of 

 the hammer on the interior of silver vessels. The specific 

 name is derived from the resemblance. 



HELIX. DEMISSA. 



Plate XVI. Fig. 16. 



H. testa depresso-convexa, peforata, luteolo-cornea, nitens ; anfractibus sex, mi- 

 nute striatis ; apatura transversa ; labro simplici, acuto ; basi glabra ; umbilico 

 parvo. 



Description. 



Animal. Not noticed. 



Shell. Depressed-convex ; epidermis yellowish horn color, 

 shining ; whorls six, with minute lines of growth ; spire ob- 

 tuse ; suture impressed ; body whorl expanding very little to- 

 wards the aperture ; aperture transverse, not large, a white 

 testaceous deposit within ; lip thin, acute ; base rather flat, 

 smooth ; umbilicus very small, umbilical region a little im- 

 pressed. 



Greatest transverse diameter rather more than three eighths 

 of an inch. 



Geographical Distribution. The only specimens which I 

 have yet seen were procured in the western part of Pennsyl- 

 vania. 



Remarks. This is a delicate and very pretty species, and 



40 



