1916] Taylor: Beavers of Western North America 429 



to the lyrate condition of temporal ridges as a character of Castor 

 canadt nsis texi nsis. While it is probable that the character is of sub- 

 specific value in the Texan form of beaver, 

 the fact that the material on which the de- 

 scription was based was exceedingly limited 

 in amount emphasizes the alternative possi- 

 bility that it is a character due to age only. 

 Fig. E. Outline of fora- ,,. ' , . ,. . ,. . ,. „ ,. 



men magnum to Significant in this connection is the further 



show method of tak- fact that in the following forms the char- 

 ing measurements. acter ig Qne ^ coudition of whieh appar . 

 About one-half nat- 

 ural size. ently depends solely on age : Castor fiber, 



Castor canadensis phaeus, Castor canadensis 



belugae, Castor canadensis canadensis, Castor canadensis leucodonta, 



and Castor canadensis frondator. 



Description of a New Subspecies of Beaver from the Cook Inlet 

 Region, Alaska 



In the labor of allocation of specimens and determination of their 

 status it soon became apparent that the skulls from Cook Inlet were 

 somewhat different from those of any other race of beaver. Examina- 

 tion of additional comparable material confirms the differences first 

 observed. 



Castor canadensis belugae, new subspecies 



Type. — Skull only, 3 youngish adult, no. 4224, Mus. Vert. Zool. ; 

 Beluga River, Cook Inlet region. Alaska; ''1907"; collected by Jacob 

 Seminoff; orig. no. 2. 



Diagnostic characters. — Perhaps nearest Castor canadensis leuco- 

 donta Gray, but crania immediately distinguishable through the nar- 

 rower blades of the hamular processes of the pterygoids in Castor 

 canadi nsis belugae ; bony ridge laterally on rostrum less strongly 

 developed in belugae than in leucodonta; belugae with tendency for 

 maxillary tooth-row, and ratio of maxillary tooth-row to basilar 

 length, to be greater. 



Belugae is similar to Castor canadensis canadensis Kuhl, but with 

 nasals of different outline, the lateral swelling being more posteriorly 

 placed; maxillary tooth-row and ratio of maxillary tooth-row to 

 basilar length tending to be greater. 



External characters. — Only one skin of the new form (no. 4347, 



