1915 | NATURAL SCIENCES OF PHILADELPHIA. oll 
Sonorella apache n. sp. Pi. VIII, figs. 2, 2a, 2b. 
The shell is depressed, with low, conoidal spire, umbilicate (the 
width of umbilicus contained nearly 9 times in the diameter of the 
shell), extremely thin; mat isabella color above, paler below, glossy 
and diaphanous in the central half of the base, encircled by a narrow 
chestnut-brown band above the periphery. Whorls 44, the embryonic 
shell comprising 13; sculptured like that of S. dragoonensis. The 
neanic whorls are very minutely crinkled and closely set with short 
bristles in irregular oblique lines. About 110 of these bristles stand 
on one square millimeter, on the upper surface of the last whorl in 
front of the aperture. The bristles are rather delicate on the last 
whorl, and in cleaning the shell they are likely to be removed in 
large part. The last whorl is wide and descends rather deeply in 
front. The aperture is very oblique, subcircular. Peristome thin, 
the upper and outer margins very narrowly expanding, basal margin 
slightly recurved, columellar margin dilated, running forward. The 
ends of the peristome converge strongly, and are connected by a 
very thin, short, parietal film. 
Alt. 10.25, diam. 16.8, width of umbilicus 1.9, aperture 8.5 x 9.7 mm. 
eeLO fe Le nam, 
Genitalia (Pl. XI, figs. 5 to 5c).—The penis is short and very thick, 
cylindric, obtuse at the ends, much shorter than the vagina. It 
has very thin walls, and is filled by a thick, fleshy papilla (fig. 5a). 
This is thick-walled with a rather large cavity having plicate walls 
so that it is star-shaped in section (fig. 5b). At the upper end of 
its cavity there is a short, conic nipple (fig. 5c); at the distal end of 
the papilla the cavity opens by a transverse slit. The retractor 
muscle of the penis is inserted on the epiphallus near the penis. 
The epiphallus passes imperceptibly into the vas deferens. There 
is no flagellum. The lower end of the vagina is swollen, having 
thick, fleshy walls. The organs measure as follows: Penis 7, 
penis-papilla 5, retractor muscle 8, vagina 11 mm. 
Dragoon Mountains, the types from the southern or Cataract 
branch of Tweed Canyon, at Station 9, on the east side of the rocky 
bed near the foot of the “‘falls,’’ No. 111,529. Also found at Station 
1, a large slide of heavy, angular stone further north on the same 
branch, rather high on the west side of the ravine, under the great 
crag. A few dead shells were found at Station 27, in a gulch of the 
rugged south wall of Tweed Canyon, and at Station 10, on the 
eastern ridge of the amphitheatre of upper Tweed Canyon. 
