108 PROCEEDINGS OF THE ACADEMY OF [Feb. 
The specimens figured (topotypes) measure: Alt. 6, diam. 13 mm., 
whorls 63; alt. 6, diam. 12.2 mm., whorls 64. The smallest specimen 
seen is from Rucker Canyon, 7,000 feet, measuring alt. 4.9, diam. 
10.5 mm., whorls 54. 
A. duplicidens stands very close to A. fissidens, but it differs by the 
more obtuse, though bluntly angular, last whorl, and by the young 
shells, which form only a very thin, narrow rib within the lip in resting 
stages, while in fissidens a very strong and heavy callus is deposited. 
The basal teeth are more united than in typical fisszdens. 
A. duplicidens, fissidens and proxima are terms of one series of 
forms differing chiefly, so far as the adult shells are concerned, in the 
degree of separation of the basal tooth, which in duplicidens is a single 
more or less bifid prominence, while in proxima there are two distinct 
teeth. When the canyons opening westward, between Rucker and 
Ft. Bowie, have supplied series of shells as copious as those we have 
obtained in the eastward canyons, another chapter may be added to 
the history of this group. 
Ashmunella angulata Pils. 
Proc. A. N.S. Phila., 1905, p. 244. 
In the south fork of Cave Creek we found this species abundantly. 
This is the type locality and here it attains the largest size. A few 
dead ones were picked up on a mountain-side southeast of Paradise, 
towards Cave Creek, and at Station 12, in Cave Creek. It reappears 
at the head of the canyon at the Falls, and at Stations 3 and 4 and 
in the head of Turkey Creek. At these places the shells are smaller. 
In 1907 Ferriss and Daniels took some specimens in Barfoot Park, 
Station la. They are much less angular at the periphery than the 
Cave Creek form. In 1908 it was taken in Horseshoe Canyon at the 
“Red Box’ (10 miles up the canyon) and at ‘5-mile camp’’; also 
in Rock Creek, at the head of Raspberry Gulch and in the Spring 
Branch of Rucker Canyon. These localities greatly extend the range 
of the species. The compressed outer basal tooth and less convex 
whorls readily separate A. angulata from A. proxima. Young shells 
deposit a lip-callus at resting periods. It is thick in the middle, 
tapering at the ends, as figured in our former paper, pl. XI, fig. 11. 
Our former figure of the genitalia of A. angulata (1905, pl. 21, fig. 26) 
is not satisfactory in one point, the slight enlargement marking the 
upper end of the penis being omitted. This enlargement is rather 
small yet distinct in the individual figured, which has been re-examined, 
and is present in all the specimens opened (seven) from several stations. 
