SOME ANIMALS OF YUKON TERRITORY 319 



Kamschatka, Ovis nivicola, suggests that all sheep from 

 north-eastern Asia, and north-western America north of 

 latitude 55 degrees, descended from the same parent 

 type. Whether in past geologic ages sheep of a uniform 

 dark color were separated by topographic and climatic 

 barriers long enough to cause a differentiation in color; 

 whether such a separation occurred before or after the 

 migration; whether in later ages the barriers were lifted 

 and a reversion in color progressed, or the sheep gradu- 

 ally intermingled all such theories are in the field of 

 speculation. 



From my point of view, however, the facts indicate, 

 during the present age, a gradual intermingling and inter- 

 breeding between the dark and white sheep, resulting in 

 the variations in color. After studying for several years 

 the nature and habits of these sheep, I am convinced that 

 among all the color varieties there is no racial antagonism 

 to interbreeding. Whenever, during the rut, a dark ram 

 has strayed from its range and joined the white ewes, it 

 has impregnated some of them. Likewise, white rams 

 have impregnated dark ewes, and ewes straying among 

 rams of a different color have been impregnated. 



The colors are most variable where the routes of travel 

 are interrupted by unfavorable topographical conditions 

 between the Pelly River and Ogilvie Rockies, and be- 

 tween Sheslay River district and Lewes River. In those 

 regions limited bands of white and dark sheep met, inter- 

 bred, and scattered throughout those sections of the 

 country. Their offspring were of mixed colors, and they 

 were continually receiving new accessions both from the 



