1906.]/ NATURAL SCIENCES OF PHILADELPHIA. 145 
Near Jerome at Mescal Gulch, Walnut Gulch, Page’s ranch, Kirwagen’s 
ranch, and drift of Verde river; Navajo Springs; Santa Rita mountains; 
Oak Creek at Owensby’s; drift of Little Colorado river at Holbrook; 
Nogales, both north and south of the international boundary. New 
Mexico: Mountain station, Oscura mountains, Socorro county; San 
Rafael, Valencia county; White Oaks, Lincoln county. 
Subgenus CHANAXIS nov. 
The shell has a large hollow axis, open below, and about one-third 
the total diameter of the shell, the structure otherwise being like 
Bifidaria s. str.; peristome continuous and free. Type, B. tuba. 
The Bolivian Infundibularia infundibuliformis (Orb.)® resembles B. 
tuba in having a very large umbilicus, and we at first thought to asso- 
ciate the Arizonian species with it; but Infundibularia differs by the 
strictly conic shell, and in the aperture, which shows but one lamella, 
a very large angulo-parietal. Other lamelle or plice, if they exist, 
must be very deeply immersed, as in the group Immersidens. 
The type of d’Orbigny’s species has been lost, and its internal 
structure is unknown. It was found with Bifidaria nodosaria (Orb.), 
a minute species, imperfectly described and figured, but probably not 
distinct from B. pellucida (Pfr.). 
Bifidaria tuba n.sp. Fig. 6. 
Shell cylindric with a short apical cone, openly umbilicate, the um- 
bilicus nearly one-third the diameter of the shell, penetrating well- 
like to the apex. Pale brown, smooth, with light growth-lines only. 
Whorls 53, convex, the apex obtuse; last three whorls forming the 
cylindrical part of the shell. The last whorl is compressed around the 
umbilicus, and scarcely straightened in front. The aperture is short- 
oval, the peristome continuous, thin and well expanded. The angular 
and parietal lamellz are combined into one long lamella, notched on 
the summit; where the two join, the inner end of the angular projects 
a little on the right side. The columellar lamella is massive, slightly 
bifid, deeply placed, and enters about as deeply as the parietal. 
There are small, short, upper and lower palatal and basal folds, in the 
typical positions, a short distance within the lip, usually with a minute 
denticle between them, and another at the base. 
Length 3, diam. 1.5 mm. 
Drift débris of the San Pedro river, Benson, Cochise county, Arizona. 
Types No. 87,062 A. N.S. Phila.; cotypes in Ferriss collection. A 
*Voyage dans l’ Amérique Méridionale, Mollusques, p. 323, pl. 41 bis, fig. 7-10. 
