158 Bulletin American Museum of Natural History. [Vol. XVI. 



darker than the males, especially on the neck and shoulders, but 

 have the grayish white areas of the males replaced by nearly pure 

 white. 



Rangtfer montanus, in late September pelage, may be de- 

 scribed in general terms as a black Caribou, with the neck and 

 shoulders, especially in the males, much lighter than the body 

 and limbs; while R. osborni, in corresponding pelage, is a 

 brown Caribou, with much more white on the rump and pos- 

 terior ventral surface, and the whole neck and shoulders, as 

 well as the back and limbs, much lighter than in R. montanus. 



The specimens of R. montanus are without measurements, 

 but the species is apparently about the same size as R. osborni, 

 as shown by the measurements of the skull given above. 



In addition to the marked contrast in color, there are strik- 

 ing differences in the size and form of the antlers in the two 

 forms, the antlers of R. montanus being of the typical Wood- 

 land Caribou type, and in their relative shortness and much 

 branched character recall strongly the antlers of R. terrcenovce, 

 but they are much lighter and more slender than in that spe- 

 cies. They have the same abrupt upward curvature of the 

 main beam, in contrast with the much longer and heavier and 

 more depressed backward-sweeping main beam seen in R. 

 osborni. 



The nearest known relative of R. osborni is R. stonei from 

 the Kenai Peninsula, which, however, is a differently colored 

 animal, with the rostral portion of the skull much shorter and 

 broader, and other important cranial differences. The antlers 

 also differ greatly in the two species, the antlers of R. stonei 

 more resembling those of the Barren Ground and Greenland 

 species. 



