1910.] NATURAL SCIENCES OF PHILADELPHIA, 139 
riss and Daniels); Nogales, S. Cruz Co. (Ashmun). New Mexico: 
- Valencia Co., along the Santa Fe R. R., at Grants (Ferriss and Pilsbry) 
and San Rafael (Ashmun); Mountain Station, Oscura Mountains, 
Socorro Co., and White Oaks, Lincoln Co., in Central New Mexico 
(Ashmun); Cook’s Peak (U.S. N. M.); Dripping Spring, Organ Moun- 
tains (Cockerell); Florida Mountains, Luna Co. (Ferriss and Pilsbry). 
B. ashmuni is distinguished by the strong development of the 
angulo-parietal lamella, which bends far to the right at its inner end, 
the very deep immersion of the lower palatal and basal folds, the 
continuation of the columellar lamella upon the parietal wall, alongside 
the parietal lamella, and the longer, usually more gibbous, “neck” of 
the last whorl. 
Fig. 31.—bifidaria ashmuni minor Sterki, Nogales, Arizona. 
B. ashmuni minor Sterki (fig. 31) is a small race, length about 1.6 
mm., with 4 to 44 whorls, found at Nogales, Arizona, and also on the 
Mexican side of the international boundary. The aperture is sub- 
stantially like that of ashmuni. 
Bifidaria cochisensis n. sp. Figs. 32, 33. 
The shell is slightly tapering cylindric, tike B. ashmuni, but the 
last whorl is less protracted and the crest or wave behind the aperture 
is very low, often not noticeable. The peristome is continuous as a 
slightly raised thread across the parietal wall (or in a less developed 
form it is rather widely interrupted above). Lamells weaker than in 
typical B. ashmuni, especially the angular lamella, which is straighter; 
parietal lamella less curved at its inner end. Columellar lamella wide 
and horizontal, not continued upon the parietal wall. Basal and lower 
palatal folds less deeply immersed than in B. ashmuni, readily visible 
in the mouth, the basal fold small. 
