1910.] NATURAL SCIENCES OF PHILADELPHIA. 55 



Key to Chiricahuan Species of Sonorella. 



a. — Penis comparatively short, very much less than the diameter of 



the shell, and about \ to \ the length of spermatheca and its 



duct (Group of S. hachitana). 



b. — Penis-papilla annulate, the free end more or less pointed; 



epiphallus less than half the diameter of shell; whorls 4f 



to 5\. 



c. — Flagellum wanting or vestigeal; diameter of shell 15.5 to 



25 mm S. optata. 



c 1 . — Flagellum distinct but minute; diameter of shell 18 to 



26 mm S. bicipitis. 



b l . — Penis-papilla plain, cylindric with obtuse end; epiphallus 



about half the diam. of shell; penis larger; whorls about 4^. 



c. — Umbilicus contained about 5^ times in diameter of the 



shell, which is depressed, 15 to 18 mm. in diameter. 



S. bowiensis. 

 c 1 . — Umbilicus contained about 10 times in diameter of shell, 

 which is subglobose, 13.5 to 20 mm. in diameter. 



S. binneyi. 



a 1 . — Penis very large, its length exceeding the diameter of the shell, 



and not differing much from the length of spermatheca and 



duct; penis-papilla and vagina veiy long (Group of S. virilis). 



b. — Shell moderately solid, larger. 



c. — Diameter of shell 16 to 21 mm S. virilis. 



c 1 . — Diameter of shell 18 to 25 mm. ; more depressed. S. v. leucura. 

 b l . — Shell thin, smaller, diameter 12 to 15 mm S. micra. 



Group of Sonorella hachitana. 



Sonorella bicipitis n. sp. PI. I, figs. 1-5. 



Shell of the group of S. hachitana, the umbilicus about one-seventh 

 the total diameter, and one-third covered by the dilated columellar 

 lip; brown, fading to white around the umbilicus, encircled above the 

 periphery with a dark chestnut band bordered above and below with 

 white bands of about the same width ; the brown band visible on about 

 two whorls of the spire, the upper white band visible also on the 

 penultimate whorl. Whorls 4f to 5, rather slowly increasing at first, 

 the penultimate and last whorls rapidly widening. Surface nearly 

 smooth to the eye, glossy. Embryonic shell consisting of H whorls. 

 The first half whorl has distinct radial ripples; the next whorl has 

 close, fine wrinkles in the direction of growth-lines, and interrupted 

 by delicate, spirally descending threads. The third whorl shows 

 some very, sparse punctation. Later whorls are marked with fine 

 growth-ripples, and visually show, under a strong lens, some exces- 

 sively faint spiral lines above the periphery. The last whorl descends 



