180 PROCEEDINGS OF THE ACADEMY OF [March, 



(3) Station C: Upper talus-slope in the bay about \ mile west of 

 Bass Camp, a few hundred feet below the rim. The shells here are 

 small, alt. 8, diam. 13, width of umbilicus 2 mm. None foimd alive. 

 In some examples the shoulder-band is extremely faint, but in most 

 of them it is distinct. 



(4) Station A: "Spectacle Cove," an embayment at the foot of 

 the cross-bed or Coconino sandstone, in a talus resting upon the Aubrey 

 red sandstone, with Oreohelix yavapai profundorum. 



Specimens measure : 



Alt. 10, diam. 16.0, umbilicus 2.1 mm. 



" 9, " 14.8, " 2.0 " 

 All have a band at the shoulder. Very few living adults were 

 taken, but, unlike the Oreohelices, the shells are entirely normal. 



(5) Seep Spring, 2 miles west of Bass Trail, at base of the cross-bed 

 sandstone. Shells like the preceding lot from the same level. 



(6) Station B: Head of Starvation Tank Wash, around the point 

 to the right from Bass Trail, at about 5,800 feet elevation (PI. XII, 

 figs. 29, 30). 



(7) Station D: Bass Trail, on the Red Wall, 5,000 feet. 

 Alt. 10.1, diam. 16, umbilicus 2.1 mm. 



" 9.5, " 16, " 2.1 " 

 " 9.1, " 15, " 2.1 " 

 The shoulder-band is wanting in about half of the shells taken. 



(8) Station E: Foot of Red Wall, on Bass Trail, elevation about 

 3,850 feet. Like the preceding, diam. 15 to 16.3 mm. A few "bones" 

 were taken still lower, at about 3,000 feet, in a talus of the Red Wall 

 limestone. 



Alt. 8.9, diam. 15.0, umbilicus 2.0 mm. 

 Fig. 29. " 9.0, " 14.3, " 2.0 " ; whorls 4$. 



" 8.5, " 13.6, " 1.9 " 

 " 8.2, " 13.5 mm. 

 The corneous, brown shell is more or less streaked with white and 

 invariably has a narrow band at the shoulder. 



(North Side of the Colorado River.) 



(9) Station F: Shinumo Creek, near camp, elevation about 2,500 

 feet. 



Alt. 10.8, diam. 16.9, umbilicus 2.1 mm.; whorls 4J. 



" 10.8, " 16.5, " 2.1 " 



" 9.3, " 15.1, " 2.0 " 



Similar shells occurred at Station 3, Shinumo Box, 2,750 feet. 



