340 



PROCEEDINGS OF THE ACADEMY OF 



[May, 



sharply costulate; buff -whitish except where darkened by the 

 presence of the soft parts, the last whorl shortly projecting; peris- 

 tome narrowly expanded. Internal lamellae one to three, but axial 

 and basal most frequent. 75 individuals opened from the type locality. 



Southern and western portions of Sheridan Canyon, at Stations 

 2, 12 and 3. Types Nos. 112,268 A. N. S. P., from Station 3, at the 

 base of a cliff near the mountain top, facing the mouth of Sheridan 

 Canyon, in company with Oreohelix ferrissi. 



Specimens from the type locality measure as follows: 



(1) An axial lamella only. 22 individuals = 29|%. 

 Length 16.9, diam. 4 mm.; whorls 16 



(2) Axial and basal lamellae. 48 shells = 64%. 

 Length 18.5, diam. 4.25 mm.; whorls 17| 



(3) Three lamellae, superior, axial and basal. 5 shells = 6f%. 

 Length 18, diam. 4 mm.; whorls 17^ 



" 16.5, " 4 " " 161 



" 16.4, " 4 " " 16 



" 13, " 4.1 '' " 14 



