MAMMALS OF THE MEXICAN BOUNDARY. 



351 



when compared with the beaver of Ajizona and Sonora. There being 

 at present no i'orest connection between the habitats of Castor fiber 

 and C. canadensis in their respective geographic ranges, and conse- 

 quently no continuity of habitat, there can be no question as to their 



specific distinctness. The skull <>t' C. canadensis frondator ( fig. 57) 

 differs from that of typical 0. canadensis in being much larger, with 

 more spreading zygomata. 



Fig ... i vstor canadensis frondator. (Type, Cat. No. 35883, U.S. N M Dorsal view; 6, 



Ventral view; c, Lateral View. 



Variation*. -Inthe v:\,i 1885 I purchased from a professional trap- 

 per I" heaver skins, taken on the Verde River during the winter of 

 L884-85. i lies skins were dried in oval shapes on looped sticksin 



