NO. 2155. NEW LAND SHELLS FROM THE WEST—BARTSCH. 333 



OREOHELIX IDAHOENSIS BAILEYI, new sabspecies. 



Plate 31, figs. 4-6. 



Shell depressed, helicoid. Nuclear whorls 2^, marked by some- 

 what irregularly disposed, crude, axial ridges, and fine spiral striations. 

 The postnuclear whorls are well rounded, marked by very coarse, 

 broad and strong, decidedly rctractively slanting axial ribs, of which 

 23 occur upon the last whorl of the type. These ribs and the spaces 

 between them are crossed by strong incremental hues. In addition 

 to the axial sculpture the whorls are marked by fine closely spaced 

 spiral striations which are best developed in the intercostal spaces of 

 the last whorl. Periphery of the last whorl with a slender keel. 

 Base broadly openly umbilicated, marked by the continuations of the 

 axial ribs which extend well within the umbilicus, and spiral sculp- 

 ture hke the upper sm-face. Aperture obhque, subcircular, peristome 

 not refleeted. 



The type and two additional specimens (Cat. No. 133221, U.S.N.M.) 

 were collected on a limestone ridge on the side of a rapid creek, at an 

 altitude of 3,700 feet, in the Seven Devils Mountains, Idaho, by ^Mr. 

 Vernon Bailey of the United States Biological Survey. This shell is 

 at once distinguished from Oreohelix idahoensis idahoensis Newcomb 

 by its much smaller size, more depressed form, decidedly open, fimnel 

 shaped umbilicus, and the presence of a slender peripheral keel. 



