144 PROCEEDINGS OF THE ACADEMY OF [March, 



the High Bridge, all in Val Verde county. Arizona: Benson. New 

 Mexico: Drift of Pecos river at Pecos (Ckll). 



It varies somewhat widely in size, and is found in great quantity 

 in drift debris along all the Texan rivers explored. 

 Bifidaria pellucida parvidens (Sterki). 



Drift debris of Pecos river at Pecos, New Mexico (Ckll.). This sub- 

 species has not before been reported from so far east. 

 Bifidaria procera (Gld.). 



Texas : Drift of Sinking Spring, San Marcos ; Hondo river drift, two 

 miles north of Hondo, Medina county. 



The var. cristata Pils. and Van. was found copiously in the drift of 

 Guadalupe river, Comal county; near Del Rio; Devil's river; and Pecos 

 river near the High Bridge, Val Verde county. Also Benson, Arizona. 

 Bifidaria contracta (Say). 



Texas: San Marcos; Guadalupe river drift, near New Braunfels; 

 Hondo river, near Hondo; Rio San Filipe near Del Rio; Devil's river; 

 Pecos river near High Bridge. Rather abundant in the river debris 

 except on the Pecos, where but three shells were found. In 1885 

 Pilsbry took specimens at Galveston. 

 Bifidaria armifera (Say). 



Texas: Drift of Guadalupe river four miles above New Braunfels, 

 Comal county; Pecos river near High Bridge. New Mexico: Pecos, on 

 the Pecos river, collected by T. D. A. Cockerell. 

 Bifidaria pentodon (Say). 



Texas: Sinking Spring, San Marcos, Hays county; Hondo river, 

 Medina county. 



Vanatta has figured one of the specimens from San Marcos. Nau- 

 tilus, XIX, pi. 6, fig. 11. 

 Bifidaria tappaniana (C. B. Ad.) 



Pupa pentodon of authors, not of Sav. 



Texas: Guadalupe river about four miles above New Braunfels, 

 Comal county (figured by Vanatta, Nautilus, XIX, pi. 6, fig. 12) ; 

 Hondo river, Medina county; Devil's river, Val Verde county. 

 Bifidaria perversa Sterki. 



Drift debris of the San Pedro river at Benson, Arizona (Ferriss, 

 1904). Hitherto known from Nogales, Arizona. (E. H. Ashmun.) 



Bifidaria ashmuni Sterki. 



Huachuca mountains, Cochise county, Arizona (J. H. Ferriss.) 

 Also from the following places, collected by E. H. Ashmun. Arizona: 



