1916] Taylor: Beavers of Western North America 437 



Comparisons op Certain American Beavers 

 castor canadensis phaeus heller, from admiralty island, 



ALASKA 



Six specimens of Castor canadensis phaeus, skins with skulls, 

 all in collection of Museum of Vertebrate Zoology : Hasselborg 

 Lake, Admiralty Island, Alaska, 4 (nos. 129, 185, 210, 211) ; Mole 

 Harbor, Admiralty Island, Alaska, 1 (no. 128) ; Pleasant Bay, 

 Admiralty Island, Alaska, 1 (no. 209). 



Three specimens of Castor canadensis canadensis, all from col- 

 lection of Smithsonian Institution, United States National Museum : 

 Nepisiquit River, New Brunswick, 2 (nos. 174525, 174526, skins with 

 skulls) ; Moose River, Ontario, 1 (no. 4358, skin with cranium 

 inside). 



Comparison With Castor canadensis canadensis Kuhl, from Eastern 

 Canada 



General external characters. — Specimens compared: Castor cana- 

 densis phaeus, nos. 128 S , 129 $ , 185 $ , 209 $ , 210 $ , aud 211 $ , 

 Mus. Vert. Zool., from three localities on Admiralty Island, 

 Alaska. May 16 to June 1, 1907 ; and Castor canadensis canadensis, 

 no. 4358 $ , May 21, 1860, and nos. 174525 S , 174526 9 , Septem- 

 ber 25, 1911 ; all U. S. National Museum coll. from eastern Canada. 



In coloration the Admiralty Island skins as a series resemble 

 tin two specimens from New Brunswick, although the type of the 

 Admiralty Island v ace (no. 209) is darker than either. No. 210 is 

 a lighter example than the rest of the series of phaeus, with more 

 cinnamon to sayal brown coloration dorsally. Canadensis no. 4358 

 is paler than the other specimens representing the same subspecies 

 (nos. 174525, 174526). 



The ratio of width of tail to its length in the two examples of 

 phaeus (nos. 209, 210) is greater, as shown below, even than it is 

 in the specimen of frondator at hand (no. 20751, U. S. Nat. Mus.), 

 attaining 54.1 percent in no. 209. The widest part of the tail, how- 

 ever, is located more proximally in phaeus than it is in frondator. 



For comparison of external characters, see table VII, opposite 

 p. 432. 



