68 PROCEEDINGS OF THE ACADEMY OF [Feb., 
slender. The papilla is cylindric, somewhat more than one-third 
the length of the penis, with a blunt, rounded end. The penis retractor 
is long. The organs measure as follows: length of penis 12 mm.; 
of penis-papilla 4.4 mm.; epiphallus and flagellum 12; flagellum 0.6; 
vagina 10; spermatheca and duct 21.5 mm. The atrium is extremely 
short. 
In its genitalia this species resembles S. binney: from the southern 
end of the range, and to a less extent S. rowelli. The embryonic 
sculpture is like that of S. bie¢pitis, but the spirally protractive threads 
are more numerous and closer. 
S. binney? differs from S. bowiensis by the very much smaller penis, 
only half the length of that of S. bowiensis in a larger shell; by the 
different shape of the papilla, and the absence or very minute size 
of the flagellum. The shell also is invariably larger than S. bowiensis, 
even in the most arid situations. 
Sonorella binneyi n. sp. PI. II, figs. 13-18. 
The shell is depressed globose, narrowly umbilicate, quite thin but 
moderately strong; pale brown with some whitish oblique streaks, 
and fading to opaque white around the umbilicus, encircled with a 
narrow chestnut band at the shoulder, narrowly showing above the 
suture on the penultimate whorl. Surface slightly shining, marked 
with fine, rather sharp growth-striz. Whorls 44, convex, the first 
minutely roughened but without distinct pattern of sculpture. The 
last whorl is very wide (viewed from above), inflated, rounded per- 
ipherally, very convex beneath. It descends in front. The aperture 
is very large, strongly oblique, elliptical, the ends of the lip converging. 
Peristome thin, very slightly expanded throughout, dilated at the 
columellar insertion. 
Alt. 15, diam. 20; width of aperture 12.8, oblique alt. 11 mm.; width 
of umbilicus 1.7 mm. 
Alt. 11.5, diam. 18 mm. 
Alt. 10.5, diam. 16 mm. 
Horseshoe (Mo) Canyon, the types from Station 1, two miles up 
the Canyon. Also found near the red box of Horseshoe Canyon. 
The genitalia (pl. III, fig. 5). The penis is somewhat longer than 
the vagina. It contracts into a narrow neck at the base, and contains 
a cylindric papilla, obtuse at the free end, and from one-sixth to about 
