70 PROCEEDINGS OF THE ACADEMY OF [Feb., 
for recognition, or at least that it is difficult to decide upon some 
specimens. Figures 1, 2, 3 represent specimens from Station 11, at 
the foot of Reed’s Mountain, Cave Creek Canyon. Figs. 4, 5 are from 
about two miles up the south fork of Cave Creek. All of these are of 
the form circumstriata. 
Fig. 6 is from Spring branch near Rucker Camp, head of Rucker 
Canyon. This shell, and others from the head of Rucker, has a broad 
conspicuous white border above the brown band, a narrower one 
below it; the brown band is broader than in Cave Creek shells. The 
spire, viewed from above, is narrower, the last whorl therefore 
wider, 
Specimens from further down Rucker have much less conspicuous 
white borders along the band, and are like the type of virilis. 
This species also occurs in Morse Canyon, tne foot of Bonito Canyon, 
and Shake Gulch, and in Horseshoe Canyon near the Red Box. 
In the Cave Creek Canyon Valley it may be found almost anywhere 
suitable rock cover exists, though there are large areas without it, 
where the slope is shght or with southern exposure. Rock “‘slides”’ 
or northern exposures with abundant rock are its chief haunts. It 
was taken at Stations 3, 4, 5, 11, 12, 18, 14, also near the branch leading 
toward Paradise, in the ravines west of Reed’s Mountain, and various 
places throughout the South Fork as far as explored—about two 
miles up. None were taken on the great ridge where Stations 6 and 7 
are situated, or on the ridge marked 10. The valley south of the 
stream from the falls has not been explored. The Sonorellas were 
also found in a great rock slide (trachyte?) on the south side of a peak 
near the sawmill, in Barfoot Park, Station 1, and in the head of the 
adjacent canyon running westward. See map on p. 107. 
S. virilis (circumstriata) was found also in Paradise Canyon about 
two miles below Paradise, and in Pine Canyon. 
Variation.—There is the usual variation in degree of elevation of 
the spire, and slight variation in ground color of the shell, in all of the 
lots examined, but various colonies differ in size, as may be seen by 
the table of measurements of specimens from four places. This size 
variation is not in the least correlated with elevation, but is invariably 
connected with the exposure to the sun. Thus it will be noted that 
at Stations 1 and 12 the mode is at 18 mm. diameter, the total range 
from 16 to 20 mm. Both of these stations are on sunny southern 
slopes, Station 1 being Barfoot Park at an elevation of over 8,000 feet, 
while Station 12 is only about 100 feet above the bottom of Cave 
