74 PROCEEDINGS OF THE ACADEMY OF [Vol. LXXV 
fresh specimens have been dissected. It must be remembered that 
all of the figures and descriptions are from alcoholic preparations. 
Besides the typical form of S. ambigua, from the southern hills 
of the Cababi group, we recognize this species in various forms 
from the Roskruge and Coyote Ranges, their outliers, and several 
ranges westward. 
Roskruck Rance Forms.—The shell characters vary from 
typical to forms with stronger parietal callus. The penis-papilla, 
while typical in shape, is not much wrinkled, generally showing some 
longitudinal or irregular and but slightly raised wrinkles towards 
the distal end (Plate V, figs. 5-7). Measurements of the organs 
follow: 
Museum No. 118081 118077 118079 118078 
Length of penis 11 14 10.5 14 14.5 
ry “* papilla Srey 9 1g ls 10 
“© epiphallus Og ow 11.5 8 12 
es * vagina 9 acre 7 10.5 
Spermatheca and duct 20 .. areas tk ge 
Station 99 100 101 106 
Plate V, fig. 7 5 6 
Bobb’s Butte, at the south end of the range, north of the Ajo 
road, different places in a malpais slide on the east side, Stations 
106-109 (1918). The size is more variable than in the Cababi 
Hills, 19.5 to 25 mm. diam. in one lot, Station 107. Some ex- 
amples are quite typical in form, but there is often a tendency 
towards depression of the spire, which is sometimes nearly flat. 
The parietal callus is generally thicker than in the typical locality, 
often with a thickened edge. 
The genitalia of a specimen from Station 106 (Plate V, fig. 4) are 
are as in ambigua except that the penis-papilla shows only a few 
pale, slightly raised wrinkles near the distal end. 
East side of the Roskruge Range in the neighborhood of Little 
Robles Ranch, Stations 96-102. The species was taken in abun- 
dance at some stations, such as 99 and 102. The specimens vary 
from completely typical in shell characters to forms with a moderate 
or heavy parietal callus, as noted above for Bobb’s Butte. Size 
variable, the largest and smallest in several lots measuring :— 
Height 15.3, diam. 25.5 mm. Station 98. 
cc 1/33 cc Dies ce as 
at 7st OB hes ny 40D. 
lis Wi Mia tr gg 
