1910.] NATURAL SCIENCES OF PHILADELPHIA. 83 



line between the two. This is the greenest in color of the group, the 

 texture of the cuticle is the most harsh and it is the largest in diameter. 



4. Form from Rucker Canyon. — The sculpture in this form is 

 weak, the oblique wrinkles smooth, in part effaced, and lower on the 

 base; spiral striation weak or subobsolete, hardly noticeable above. 

 Cuticle glossy, persistent, varying from rather bright green or greenish- 

 yellow to brownish-olive, the two brown bands distinct. There are 

 sometimes two fainter bands, one above, the other on the base. The 

 last whorl is only very obtusely angular, the angle, well rounded, usually 

 falls less in front than in the Onion Creek lot. The aperture is con- 

 spicuously longer than in typical 0. clappi; upper margin decidedly 

 arched. In old shells the lip-ends approach closely, but are not 

 connected as in the typical 0. clappi, the callus between them remaining 

 thin and transparent. 



Up to 3+ whorls the young carry five strong cuticular fringes below, 

 one at the periphery and one above. The cuticle in larger shells is 

 smooth. 



The largest in 45 measured : 



This is the handsomest of the group in color and, with the exception 

 of 0. c. cataracta, the smoothest, the base being polished with somewhat 

 of a varnish-like gloss. The last whorl is even more rounded per- 

 ipherally than in typical 0. clappi. In 1908 it was found in a deep 

 gulch, the "box" of Rucker Canyon, at about 8,000 feet elevation, 

 on both sides of the stream in sliding rock, where the atmosphere was 

 as moist as the stations on Cave Creek, about 12 miles distant. It is 

 a near neighbor with O. barbata, a small form of the latter being plenti- 

 ful at the twin caverns in the box, while O. clappi was found half a 

 mile farther down the stream. 



5. Shake Gulch Form. — The shell is sharply angular peripherallv, 

 the angle becoming obtuse near the lip; whorls flattened above; 

 cuticle dull, lusterless, persistent, obscure olive at the base, the upper 

 surface with a russet suffusion, peristome black-bordered. There are 

 one or two faint bands. The surface is obliquely, rather obtusely, 

 wrinkled, the base distinctly striate spirally, growth-lines low, not 

 waved. The sculpture of the embryonic shell is very weak, and 



