60 EXTINCT AND VANISHING MAMMALS 



WARREN, E. R. 



1926. A study of the beaver in the Yancey region of Yellowstone National 

 Park. Roosevelt Wild Life Annals, vol. 1, pp. 13-191, illustr., maps. 



1926. Notes on the beaver colonies in the Longs Peak region of Estes Park, 

 Colorado. Roosevelt Wild Life Annals, vol. 1, pp. 193-234, illustr. 



1927. The beaver: Its work and its ways. Amer. Soc. Mammal. Monogr. 2, 

 177 pp., illustr. Baltimore. 



BAILEY'S BEAVER 

 CASTOR CANADENSIS BAILEYI Nelson 



Castor canadensis baileyi Nelson, Proc. Biol. Soc. Washington, vol. 40, p. 125, Sept. 26, 

 1927 (Humboldt River, 4 miles above Winnemucca, Nevada). 



This race of the beaver is darker than frondator and has a 

 slenderer skull. From C. c. pacificus from the Columbia River 

 drainage in eastern Washington and Oregon it differs in its 

 distinctly paler color and slenderer skull. The narrow skull 

 and especially the rostrum of the Humboldt River beaver 

 contrast strongly with the massive skull and broad heavy 

 rostrum of subauratus (Nelson, loc. cit.). The upper parts 

 are described as "dull rusty chestnut, brightest on crown 

 with a dull yellowish shade on the cheeks; ears dark brown; 

 base of tail all around uniform with adjacent parts of body; 

 tops of hind feet dark chestnut; underparts of body dull drab 

 brown." Total length of type, 1,064 mm.; tail, 254 by 135; 

 hind foot, 183. 



Concerning this race of the beaver little seems to be in 

 print. Dr. Nelson had specimens from Winnemucca, Iron 

 Point, Golconda, and Deeth in Nevada. It is presumably con- 

 fined to the region of the Humboldt River Basin of Nevada. 

 Borell and Ellis (1934) wrote of it a few years ago: "Beavers 

 are found in limited numbers along the main branches of the 

 Humboldt River, but have been almost completely extermi- 

 nated along the smaller streams which flow out of the Ruby 

 Mountains. Mr. August Rohwer and Mr. William Toyn re- 

 ported that there were still a few beaver in one or two of the 

 canyons on the west slope of the Ruby Mountains. Character- 

 istic beaver gnawings found by us on some partly decayed aspen 

 stumps at about 7,000 feet altitude along Toyn Creek, near the 

 summit of Harrison Pass, indicated the former presence of 

 beaver there." 



Still more recently, Vernon Bailey (1936) has reported that 

 "these desert-valley beavers are still found in the Great Basin 



