1910.] NATURAL SCIENCES OF PHILADELPHIA. 77 
S. micra occurs associated with Ashmunella lepiderma in the same 
rock slides. Both are modified in the same manner, the shell differing 
from allied species in being smaller, thinner, dull, with a greater or 
less development of cuticular processes. The reduced size compared 
with the species on the opposite side of the canyon is without much 
doubt due to the sun-scorched exposure. We have not found that 
living on igneous rock has any tendency to dwarf Sonorellas, though 
the tenuity of the shell may fairly be attributed to that influence. 
The animal in alcohol is pale grayish, darker on the back. Sole 
with the usual pale central area and slightly darker side areas, not 
defined by lines. 
The genitalia of a drowned specimen in good condition from Station 
10 is drawn in pl. V, figs. 1, 2. Unfortunately the penis was exserted 
in all of this lot. Except in being smaller and more slender, the organs 
resemble closely those of S. virilis. The penis in this figure is shown 
partially everted, the long papilla (pp.) projecting. In fig. 2 the 
epiphallus is shown partially uncoiled. The flagellum is well developed 
for a Sonorella, Pl. V, fig. 3, represents the organs of another speci- 
men, from Station 17, with the penis normally retracted. The end 
of the penis-papilla is shown in outline 
Measurements in millimeters of the genitalia of two specimens 
follow: 
| | | | E | | | 
| perma- | 
| 
Penis. Papilla. Ppiphallus. Flagellum. Vagina, eithees | tract pane Me oP enal 
17 14 | 1Os50 4 O26) || 8 16 8+ 14.8 94 334 
140)" Ad | 13 | One 1.9 17, 4.5 14 94,330 
| | 
Genus OREOHELIX Pilsbry. 
The Chiricahua Mountains harbor two groups of Oreohelix with a 
well-developed nearly black, green or yellow cuticle, so far unknown 
elsewhere. In one of these, the barbata group, the shell is bi-convex, 
with whorls of small calibre, a wide umbilical cavity and numerous 
spiral wreaths of cuticular fringes. The other, the O. clappi group, 
has an orbicular shell usually banded, with large tubular whorls and 
a smaller, rapidly diminishing umbilicus. In one of the forms both the 
cuticle and the shell beneath possess well-defined spirals similar to 
the cuticular fringes of O. barbata; but here the likeness ends. In 
general appearance these Chiricahuan forms have little resemblance 
to groups of Oreohelix in the Huachucas or elsewhere. The clappi 
