MAMMALS OP THE MKXICAN BOUNDARY. 



351 



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

 at present no forest connection between the habitats of Oastor fiher 

 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 of C. canadensis frondator (fig. 57) 

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

 more spreading zygomata. 



Tig. 57.— Castor canadensis fkondatok. (Type, Oat. No. 36883, U.S.N.M.) m, Doksal view; 6 

 Ventkal view; c, Lateral View. 



Variations. — In the year 1885 I purchased from a professional trap- 

 per 17 beaver skins, taken on the Verde River during the winter of 

 1884-85. Theso skins wero dried in oval shapes on looped sticks in 



