86 



PROCEEDINGS OF THE ACADEMY OF 



[Feb. 



tt. — .Sculpture of sharp fine striae along the lines of growth, conspicuous 

 on the base, where there are also spiral stria? and some widely 

 spaced larger spirals. 

 b. — Shell smaller, diameter about 11 mm., whorls -H to 5; peripheral 



keel well expressed 0. ehiricahuana. 



b 1 . — Shell larger, diameter about 14 nun., whorls 5^; peripheral keel 

 strongly projecting, the whorl hollowed above and below 



it 0. c. percarinata 



a 1 . — Sculpture obsolete, the oblique stria? course and blunt, the base 

 especially much smoother; spiral sculpture weak or wanting; 

 diameter usually 12 to 15 mm., whorls 5^ to 5i 0. c. obsoleta. 



The type locality is on the slope with southern exposure below the 

 cave in Cave Creek Canyon, Station S on map, p. 107. The dry 

 ravine has steep sides of steeply dipping, more or less calcareous shale 

 and earth formed by its. decomposition. The dead shells are profusely 

 scattered; living onas are under dead mescal (Agave), sot ol (Dasyli- 

 rion) and bear-grass, with Thysanophora horni, Succinea avara, Vitrea 



Fig. 10. — 0. ehiricahuana, Cave Creek, Fig. 11 — 0. c. percarinata P. and F., 

 Station 8. Cross J Mountain 



indentata and Holospira. The colony here is about 250 yards long 

 and perhaps 100 wide in the widest place. The shells are very uniform 

 in size: 



Alt 6 6.8 6.5 6.5 6.8 6.8 mm. 



Diam 11.1 11 11 11 10.5 11.5 mm. 



The shells are white, with the earlier whorls flesh-tinted, a faint 

 fleshy-corneous band at the outer third of the top of the last whorl, 

 which has two grayish or fleshy corneous bands on the outer half of 

 the base or a general fleshy corneous suffusion there. A scalariform 

 mutation rarely occurs. 



From the cave we found large colonies at intervals westward nearly 

 to the western rim of the valley, at Stations 5, 6 and 7 on map, p. 107. 

 At Station 5, on a steep north slope along the creek, under rocks, 

 about 3 miles west of the cave, the shells are similar but larger, 12 to 

 13 mm. in diameter. 



