1915.] NATURAL SCIENCES OF PHILADELPHIA. 407 



Sonorella sitiens n. sp. PI. VIII, figs. 5 to 5c. 



The shell is depressed, umbilicate (the width of umbilicus con- 

 tained nine to ten times in the diameter of the shell), rather thin, 

 cinnamon colored (varying in tone), paler around the umbilicus, 

 encircled by a chestnut-brown band at the shoulder, bordered with 

 a white band above and below. Surface somewhat glossy. The 

 initial fourth of a whorl is smooth; the rest of the embryonic shell 

 has very fine, anastomosing and interrupted radial wrinkles, and on 

 some specimens there are the faintest traces of spiral threads. The 

 neanic and last whorls are marked with delicate growth lines. Spire 

 low; whorls 4|, convex, the last slowly descending in front. Aper- 

 ture oblique, rounded oval. Peristome thin, the upper margin hardly 

 expanded, outer and basal margin, a little expandmg. 

 Alt. 11, cUam. 20 mm.; aperture, alt. 10, diam. 12 mm. 

 The back, top and sides of head are slate colored, the tail and a 

 wide band above the foot edges whitish. 



Genitalia (PL XIII, fig. 3). — The penis is swollen distally, becoming 

 narrow in its basal half, which is enveloped in a muscular sheath, 

 the outer edge of which is attached to the end of the epiphallus. 

 The penis-papilla is extremely short and wide, cylindric, with a few 

 annular corrugations and a shortly "conic end. The epiphallus is 

 slender, swollen at" its distal end, without trace of a flagellum. The 

 lower part of the vagina is very stout. Other organs as usual. 

 Jaw (PI. XIII, fig. 7) has 8 strong, narrow ribs. 

 Northwestern end of Las Gijas above Las Gijas Mine, Pima Co., 

 Arizona. Types No. 112,158, A. N. S. P., taken by Ferriss and 

 Pilsbry, September 27, 1910. 



The shell is less solid than S. eremita, the aperture decidedly larger, 

 the umbilicus smaller. The color also is darker. It differs from 

 eremita conspicuously in the genitalia, the penis of S. sitiens being 

 provided with a sheath of half its length, and the papilla being 

 extremely short and stout, while in S. eremita the sheath is repre- 

 sented only by a few loose muscular fibres at the base, and the 

 papilla is very slender and comparatively long. No other Sonorella 

 known has a penis-papilla like that of S. sitiens. Several specimens 

 dissected are entirely similar in genitalia. 



The spire is very low in most of the specimens, but in one (PI. 

 VIII, fig. 5c) it is more conic. In this shell the white borders of the 

 shoulder band are very narrow. It measures, alt. 12, diam. 18.5 

 mm., aperture 9.5 mm. high, 10.8 wide. 

 Five other adult shells measure: 



