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. binneyi from the southern 

 end of the range, and to a less extent S. rowelli. The embryonic 

 sculpture is like that of S. bicipitis, but the spirally protractive threads 

 are more numerous and closer. 



S. binneyi 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. bp. 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-stria?. Whorls 4i, 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 beneatn. 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. 13, diam. 20; width of aperture 12.8, oblique alt. 11 mm.; width 

 of umbilicus 1 . 7 ram. 



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 (pi. Ill, 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 



