SOME ANIMALS OF YUKON TERRITORY 301 



horns, and their body measurements do not differ materi- 

 ally. It remains to examine their skulls and to study their 

 variations in color. 



Difference in skull characters have been detected 

 among sheep in three widely separate areas: the Stikine 

 River region, the east slope of the Mackenzie Rockies, the 

 whole of the areas inhabited by sheep elsewhere; but as 

 yet no satisfactory study has been made, since the avail- 

 able series of adult skulls from each locality have not been 

 brought together for careful comparison. Such a com- 

 parison may result in the elimination of most of the sup- 

 posed differences, and under any circumstances, by skull 

 characters alone, the sheep could only be separated into 

 weak subspecies. At the present time only one positive 

 statement can be made. The differences in skull char- 

 acters are slight. 



The northern sheep do not undergo seasonal changes 

 in color, but they do present marked individual and local 

 color variations, the study of which is beset by perplexing 

 problems. In this connection a few words on the distri- 

 bution of sheep in the Yukon Territory will be helpful. 

 A detailed description of distribution cannot be given 

 in the space of this chapter, and besides, the exact topog- 

 raphy in many areas and the occurrence of sheep in each 

 are not known. Nevertheless, facts sufficient for a few 

 generalizations have come under my observation. 



Except within the humid belt of the Coast Ranges, 

 sheep exist on nearly all the mountains which rise rough 

 and rocky, well above timber-line. Sheep do not live on 

 lower mountains, the areas of which above timber-line 



