1916 J Taylor: Beavers of Western North America 421 



No differences in relative amounts of underfill' and overhair can be 

 clearly correlated with age. No individual out of four juvenals at 

 hand (nos. 12109, 12110, 12106. and 12105, taken June 20 to 27) 

 has the overhair so worn as it is in certain adults (as nos. 12108 and 

 12107, taken June 25). 



The coloration of the underfur changes little with age, varying 

 above, in both old and young, from fuscous and fuscous-black to 

 benzo and hair brown, and varying beneath about light drab and 

 light cinnamon-drab. One adult specimen (no. 12101) has the under- 

 fur above an almost uniform drab. 



Two very young juvenals, loaned by the Biological Survey (nos. 

 71S30, 71833) are very similar to the juvenals mentioned above. 

 Being younger, the hair of nos. 71830 and 71833 is noticeably shorter, 

 softer, and fluffier. The only difference in coloration is a slightly 

 darker general effect dorsally. 



Dorsal coloration. — There is in the older animals a distinct dark- 

 ening in dorsal appearance, the color varying from cinnamon to chest- 

 nut. This darkening is partly the result of darker coloration of 

 individual hairs, and partly the result of the showing through to a 

 greater degree of the dark underfur. The juvenals are pinkish 

 cinnamon to cinnamon, sometimes a little darker dorsally. 



The forefeet are near warm sepia or mars brown in the young, 

 while in the older ones they have a deeper shade and exhibit some- 

 thing of a luster. 



The hind feet of the young are near mars brown, although it is 

 very difficult to fix the tone, while those of the adults are browner, 

 varying from near carob brown to near hazel. 



Ventral coloration. — The juvenals have more of a golden luster 

 ventrally along the sides of the belly than the adults. The coloration 

 mid-ventrally varies about drab in the juvenals, with a tendency to 

 be darker in the adults. The area just anterior of the tail ventrally 

 varies in the adult between cinnamon-brown and chestnut or bay, 

 while in the juvenals it varies between walnut brown and cinnamon- 

 buff. 



Molt and range of individual variation. — Adequate material for 

 the study of the molting process in beavers is lacking. It seems 

 probable that the molt is not regional, as it is in chipmunks and 

 gophers, but general, the hair being renewed gradually all over the 

 body. 



