68 EXTINCT. AND VANISHING MAMMALS 



These southern beavers attain a large size; Howell speaks of 

 one killed on Pintlala Creek that weighed 65 pounds. Another 

 from Catoma Creek weighed 38.5 pounds and measured 1,035 

 mm. in total length; tail, 290 by 163; hind foot, 170. Compared 

 with a specimen of the typical race from Canada, its skull is 

 shorter and relatively broader, with wider brain case and 

 interorbital region. 



In Kentucky, which should come within the western range of 

 this race, Funkhouser (1925) writes: "We can find no record 

 of its having been seen . . . within the past twenty 

 years." In earlier times it was occasionally mentioned by the 

 pioneers, but "was probably never very abundant in Ken- 

 tucky." 



COLORADO BEAVER 



CASTOR CANADENSIS CONCISOR Warren and Hall 



Castor canadensis concisor Warren and Hall, Journ. Mamm., vol. 20, p. 358, Aug. 14, 

 1939 ("Monument Creek, southwest of Monument, El Paso County, Colorado"). 

 FIGS.: Warren, 1910, p. 141, figs. 46-48 (photographs; skull). 



Until recently the beaver of Colorado was believed to be the 

 same as the race frondator, typical on the Mexican boundary of 

 Sonora. Now, however, the above authors, after a minute 

 study of a series of skulls, believe that it represents a recog- 

 nizable subspecies, of dark color, but with a skull resembling 

 that of mexicanus, yet on the average differing in the size and 

 shape of the angular process of the mandible, which is longer 

 and more produced posteriorly and sharp-pointed rather than 

 short and posteriorly rounded. Other slight differences seem 

 to separate the Colorado beavers from adjacent races. Greatest 

 occipitonasal length of skull, to 145.2 mm.; length of nasals, 

 50-54.4. 



Warren (1910) writes that although the beaver "was no 

 doubt at one time found in every county in Colorado which 

 contained streams with sufficient water for its needs, and to- 

 day, in spite of the persecution to which it was at one time 

 subjected from the trappers, nearly resulting in its extinction, 

 it is found over a large area of the State, and thanks to the 

 protection accorded it by law, is on the increase. We have 

 records of it from Larimer, Weld, Morgan, Grand, Routt, 

 Arapahoe, Gunnison, Delta, Garfield, Eagle, El Paso, Teller, 

 and Mineral counties," thus covering much of the west-central 



