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1923] NATURAL SCIENCES OF PHILADELPHIA 85 
Sonorella binneyi imperialis n. subsp. Plate 2, fig. 12; pl. VII, fig. 1. 
Empire Range, Station 151 (1918); a few “bones” at Station 150. 
The shell is decidedly more depressed than S. binneyi, rather 
narrowly umbilicate (umbilicus about one-ninth to one-tenth the 
diameter), thin, dilute cinnamon above, shading into white be- 
neath, with a chestnut-brown band rather indistinctly whitish- 
bordered. There are some narrow whitish growth-arrest streaks. 
Surface glossy, with light, fine growth lines. Embryonic shell, 
after the smooth initial part, radially anastomosing-crinkled, then 
with slowly protractive threads over fine radial crinkling, and on 
the last part of the first whorl, retractive threads. The spire is 
small. The last whorl increases very rapidly and is unusually 
wide, as viewed from above. In front it descends a little and slowly. 
The aperture is large, its width decidedly more than half the 
diameter. Lip thin, very slightly expanded, outwardly and basally, 
dilated at the columellar insertion, partly covering the umbilicus. 
Height 11.3, diam. 19.5 mm.; 43 whorls. 
By its large aperture, texture, lip and apical sculpture this species 
resembles S. baboquivariensis P. & F., but in that species the 
aperture is even larger and the umbilicus more covered; moreover, 
the penis papilla is noticeably different, though otherwise the 
genitalia are rather similar. It differs from the typical Chirica- 
huan S. binneyi chiefly by being more depressed. The genitalia 
of this species show affinity to S. bowtensis and S. bartschi—species 
in which the umbilicus is decidedly larger. 
The few living ones and numerous ‘‘bones”’ show very little 
variation in size, nearly all being from 19 to 20 mm. in diameter. 
S. binney?, while it has a remarkably wide range for a Sonorella, 
appears everywhere to be very local. In the Chiricahuas it is 
known from a single canyon in the southern part of the range. 
The form we called franciscana has a very limited area, separated 
from the Chiricahuan locality by valleys and by ranges where we 
know that binneyi does not occur. S. b. franciscana differs from 
the original lot by having a somewhat longer epiphallus, a difference 
of no great weight, and perhaps it is not really distinguishable 
from typical S. binneyi. The Empire Range form, S. 6. imperialis, 
lives about 90 miles northwest of the type locality, several inter- 
vening ranges which we have explored being without the species. 
It has a more depressed shell than typical binneyi, and the penis- 
papilla is thicker. Finally in the Tucson Range, still further west, 
we have an allied form, S. baboquivariensis depressa, in which the 
penis-papilla is very slender. 
