290 PROCEEDINGS OF THE ACADEMY OF [Nov.—Dec., 
tained about 1.63 times in that of the shell, and in another locotype 
(pl. IV, figs. 3-3b) it is contained nearly 1.8 times. In the smaller 
mouthed individuals the umbilicus is somewhat larger and less 
covered, and the last whorl, viewed from above, is not so wide. We 
have tried in vain to use these characters for a separation of the 
series (some hundreds of shells); but while the extremes in size 
of aperture appear quite distinct, the distinction could not be carried 
through, as nearly every station supplied individuals with large, 
intermediate and small apertures. 
The specimens from low in Sabino canyon usually have more . 
solid, thicker shells than those from higher; but this is not always 
the. case. 
It is a species of the arid mountains, confined to lower elevations 
than S. marmorarius. 
Vig. 3.. Sonorella sabinoensis, Sabino Canyen, genitalia. a, b, No. 109,098; c¢, 
No. 109,097; d, No. 109,094. 
The smallest shells, diam. 19 mm., were found at Station 15, low 
in Sabino canyon (about 4,000 ft.); but others up to 25 mm. diam. 
occur in the same place. The largest, 27 mm. diam. are from 
Station 9, 1913, the bluffs opposite Station 15. One of this lot is 
figured, pl. IV, figs. 4-4b. 
The degree of depression is variable in the same lot. Specimens 
selected from a station on Vantana canyon measure: 
Alt. 14.5 diam. 26, mm. (largest)... 
eS Lee Ree ‘“ (most depressed). 
196A 8 O48 SCS elevated): 
pare 8 eae ae | ‘* (smallest). 
Figures 5 to 5d are depressed and elevated shells from Bear canyon. 
