NATURAL SCIENCES OF PHILADELPHIA. 363 
* “ MOLLUSCA OF THE SOUTHWESTERN STATES, VII: THE DRAGOON, MULE, 
“a SANTA RITA, BABOQUIVARI, AND TUCSON RANGES, ARIZONA. 
it 
‘ BY HENRY A. PILSBRY AND JAMES H. FERRISS. 
_ This paper and the preceding one (VI) contain the account of 
‘mollusks collected in course of our explorations in 1910, from the 
middle of August to the middle of October. The forms obtained 
in the Santa Catalina Mountains will be described in connection 
with the collections made there by one of us (Ferriss) in 1913. We 
were ably assisted in the field by Mr. L. E. Daniels.t_ Besides the 
ranges enumerated in the title, some account is given of several 
minor hill groups, all in the region south of the Southern Pacific 
Railroad. While this paper, with those already published on the 
Chiricahua and Huachuca Ranges, is monographic for the mollusks 
of Arizona south of the Southern Pacific, yet the field is far from 
exhausted. Our work is a reconnaissance rather than a complete 
malacological survey. Further species will reward search in the 
southwestern end and outliers of the Chiricahuas, the southern 
_ Dragoons, the Whetstone Range, and the mountains around and 
7 “south of Tombstone. Further west we have explored only small 
middle sections of the Santa Rita and Baboquivari Ranges. Many 
hill and mountain groups between Tucson and Nogales remain 
untouched, most of them doubtless inhabited by endemic species 
of Sonorella. In the nearly waterless region westward between 
the Baboquivari Range and the Colorado River, almost nothing 
has been done aside from some account of the snails of the Comobabi 
- Mountains, which we are now giving. 
_ Going westward in southern Arizona from the eastern limit of the 
State, the general level falls and the mountains become lower and 
smaller. There is a gradual elimination of snails requiring a reason- - 
able degree of humidity. Ashmunella and Oreohelix extend west to 
the Huachucas. Beyond that range they disappear. The small 
shells also abruptly diminish in number of genera and species, by 
i 1 We are indebted to Mr. J. C. Blumer, of Tucson, for several species from the 
a Comobabi and Cababi Mountains, which we did not visit. 
