140 PROCEEDINGS OF THE ACADEMY OF [Feb., 
ree ag cian a Wee: i Cotypes, Tanner Canyon, fig. 32. 
99 15, a Sante. Rita Mountames, tgs so, 
Southeastern Arizona: Chiricahua Mountains, White Tail Canyon; 
Summit of Cross J Mountain, Big Emigrant Canyon (Ferriss and 
Pilsbry). Huachuca Mountains, Tanner Canyon, 6,000 feet (Ferriss,. 
type loc.). Santa Rita Mountains (Ashmun). 
Fig. 32.—Bifidaria cochisensis P.and F. Types from Tanner Canyon, Huachuca 
Mountains. 
The absence of a forward continuation of the columellar lamella 
on the parietal wall, between the parietal lamella and the columellar 
wall, is the most prominent feature of this species, though it has several 
other constant, if less conspicuous, differential characters. It is de- 
cidedly less aberrant than B. ashmuni, the lamelle and folds, as well 
as the less protracted last whorl, approaching the normal Bifidaria 
type. 
A modification of B. cochisensis also occurs in the Huachueas at 
Tanner Canyon and in the Chiricahua range on Limestone Mountain. 
The shell is smaller than usual in cochisensis, about 1.9 or 2 mm. long. 
The teeth are much weaker, especially the angular lamella. The 
inner end of the parietal lamella is not much curved and is readily 
visible in an obliquely basal view in the aperture. The basal and 
palatal folds are less deeply placed, the lower palatal being visible 
below the apex of the parietal barrier,in a front view. The basal 
