8G EXTINCT ND VANISHING MAMMALS 



SNAKE RIVER BEAVER 



CASTOR CANADENSIS TAYLORI Davis 



Castor canadensis taylori Davis, The Recent Mammals of Idaho, p. 273, Apr. 5, 1939 

 ("Big Wood River, near Belle vue, Blaine County, Idaho"). 



The beaver of the Snake River drainage basin in southern 

 Idaho and northern Nevada has lately been distinguished on 

 the ground of its "averaging darker" than the race bailey i; 

 "nasals long and narrow (breadth averaging 46 percent of 

 their length); anterolateral rim of orbit narrow (near 7.0 mm.); 

 occiput nearly vertical." 



No details are at hand concerning the past or present status 

 of this beaver. Davis based his description on 11 specimens 

 from Ada, Lemhi, Blaine, -and Bannock Counties in Idaho and 

 four from Goose Creek, Elko County, Nev. 



TEXAS BEAVER 



CASTOR CANADENSIS TEXENSIS Bailey 



Castor canadensis texensis Bailey, North Amer. Fauna, no. 25, p. 122, Oct. 24, 1905 



("Cummings Creek, Colorado County, Texas"). 

 FIGS.: Davis, 1940, pp. 85-86, figs. 1, A, and 2, D. 



This seems to be a slightly marked form, described as re- 

 sembling frondator in its pallid coloring, but distinguished by 

 the skull, in which the sagittal crest is short and the lateral 

 ridges lyrate or spreading even in old age; supraoccipital crest 

 doubly curved, nasals long, spatulate, and tapering to a 

 narrow point posteriorly. These characters shown in the three 

 specimens studied by the describer "are so well marked and 

 uniform as to justify describing the subspecies, even on so 

 scanty material." The localities given are on the Colorado 

 River of east-central Texas, but "whether the beaver of other 

 streams north and south" of this valley are the same "can be 

 settled only by specimens." More recently the matter was 

 reviewed by Dr. W. B. Davis (1940) with additional specimens, 

 and he concludes that the distinctive characters of texensis 

 are its "relatively darker color; posteriorly pointed nasals, 

 with an expanded area near middle of rostrum; dorsal outline 

 of skull nearly flat, except for the distal portion of the rostrum 

 which is abruptly depressed; tail relatively long and narrow, 

 ratio of width to length, 48 (39-55)" as compared with the 



