92 PROCEEDINGS OF THE ACADEMY OF [Feb.,. 



in color from pale greenish to dark reddish brown, some with wide 

 indistinct red bands. Many lose their fringes and part of the cuticle 

 before maturity. In (me colony the shells were entirely naked. The 

 rows of cuticular fringes vary in number from five to ten. In size, 

 the shells are from 1-U mm. diameter down to 10 mm. in the race 

 minima. Elevation above the sea apparently does not control size. 

 The smaller forms usually dwell at 10,000 feet, and the largest at 

 7,000, but a pigmy form was found at the lowest altitude, and the 

 most robust at about 8.500 feet. 



The deflection or dropping of the last whorl at the aperture is not 

 uniform or consistent in any colony, but it has significance in connec- 

 tion with the proportion of individuals so modified. In some colonies, 

 as that in Cave Creek, the last whorl as a general rule drops very little, 

 while in Barfoot Park it usually descends deeply. 



In Cave Creek Canyon this species is confined to the border and 

 slope of the western escarpment. Ferriss (1904) took the types in 

 the talus half a mile below the falls of Cave Creek. These have 4£ 

 whorls, and are pale greenish ; the cuticular laminae light russet. There 

 are four to six, usually five, circular wreaths of triangular cuticular 

 scales, one small one being midway between periphery and suture, 

 but often wanting, one at periphery, and three or four on the base. 



The last whorl is strongly angular throughout, and usually does not 

 descend very deeply in front. Parietal callus thin and moderately 

 long. 



Alt. 7, diam. 13.5 mm., not including cuticular processes. 

 " 5, " 12 mm. 



In 1906 we found almost similar specimens at Station 4 (marked by 

 two dots on the map, p. 107), darker in color, with sometimes as many as 

 eight cuticular wreaths, sharply carinated or angular at the periphery. 

 These were on a well-shaded northern slope, under rocks in a coarse talus. 

 This place is two or three hundred feet above the bed of the "wash" 

 and about one hundred below the cliffs, just opposite a little grove 

 of aspens among the oak scrub, which form a conspicuous landmark 

 near the head of the "wash," from their rarity in this canyon. The 

 snails here had been preyed upon by the mice. 



In Turkey Creek near the head of one of the eastern branches at 

 an elevation of about S.500 feet, Ferriss and Daniels took fully devel- 

 oped examples in 1907 (pi. VI, figs. 1, 2, 3). The shells are strongly 

 angular to the aperture, and measure 13 to 14^ mm. diameter, with 

 4£ to 4f whorls. They have 7 beautifully developed wreaths, in the 

 best preserved individuals. The last whorl drops fully 2 mm. at the 



