206 WEST AMERICAN SHELLS — STEARNS. 



Order PULMONATA. 

 Suborder Geophila. 

 - Family Helicid^. 



Genus HELIX Liun6. 



Group Ariouta Leach. 



Helix (Arionta) coloradoensis sp. nov. 



Plate XV, Figs. 6, 7, 8. 



Shell orbicular, moderately depressed, whorls slightly elevated, apex 

 obtuse, number of whorls four to four-aud-a-half, rounded. Umbilicus 

 narrow, showing the penultimate whorl, though partially covered by 

 the reflection of the lip at the point of junction with the base of the 

 shell. Aperture obliquely ovate, nearly circular, and almost as broad 

 as high. Lip slightly thickened and reflected, or simple, varying in 

 this respect ; more reflected and aperture more effuse at the cohimella. 

 Parietal wall in the heavier examples calloused, the callous connecting 

 with the inner edges of the outer lip above and below. Shell rather 

 fragile, thin, translucent ; surface smooth and shiny, and sculptured 

 with fine incremental lines. Color pale horn to white, and otherwise. 

 marked by a single narrow revolving reddish-brown band just above 

 the periphery, which in some specimens is obscure or absent. In some 

 individuals certain faint scars upon the upper whorls imply an occa- 

 sionally hirsute character. 



Millimeters. 

 Maximum diameter of largest 15.25 



Miuimum diameter of largest 13. 25 



Altitude of largest 10.25 



Maximum diameter of smallest adult 13.75 



Minimum diameter of smallest adult 12. 00 



Altitude of smallest adult 8.75 



Habitat. — Grand Caiiou of the Colorado, opposite the Kaibab pla- 

 teau, at an elevation of 3,500 feet. (Mus. No. 104100.) 



The above, while exhibiting a facies or aspect of its own, is never- 

 theless suggestive of H. Bemondi Gabb, Mazatlan, in the Mexican State 

 of Sinaloa, and also from the high mesas or table-lands in the neigh- 

 borhood of Mulege, Lower California. R. Carpenteri Newcomb, which 

 is a synonym of H. Bemondi, is credited by the author to " Tulare Val- 

 ley," and has been found in other localities in California. A glance at 

 the map will show how widely separated geographically, R. Colorado- 

 ensis is from its nearest allies, and this discovery of Dr. Merriam's 

 extends the distribution of the west coast type of Relices farther to 

 the eastward than heretofore, and adds an area of great extent to that 

 previously known, 



