208 MOSTLY MAMMALS 



summer. Again, many mammals vary to a great extent 

 in coloration according to locality, so that there may be 

 dark-coloured and light-coloured races inhabiting different 

 localities. The most striking instance of this is, perhaps, 

 the big-horn wild sheep of North America, which in the 

 Rocky Mountains is a khaki-coloured animal with a white 

 rump, but in Alaska is nearly pure white all over through- 

 out the year. It is true, indeed, that American naturalists 

 prefer to regard the big-horns of the Rocky Mountains and 

 Alaska as distinct species rather than local races of a 

 single variable animal, but for our present purpose such 

 slight differences of opinion do not really affect the case 

 one way or the other. 



That white fox and blue fox skins are not (as was once 

 supposed to be the case by some naturalists) the summer 

 and winter coats of the same individual animals will be 

 apparent by a comparison of furs of the two descriptions 

 worn by our lady friends. Both descriptions have the 

 same long thick hair, with a woolly under-fur at the base, 

 and are evidently the winter coats of the animals to which 

 they respectively belong. Indeed, with all long-haired 

 animals of the northern parts of the Old World, with the 

 possible exception of the Polar bear, it is the winter coat 

 that is alone valued by the furrier. 



That blue and white foxes are not local races of the 

 same species (or distinct species) is evident from the fact 

 that in certain districts both occur together, although in 

 other localities (as in Iceland, where all the foxes are 

 blue) only one form may be met with. It is, indeed, 

 possible that in some cases blue and white cubs may appear 

 in the same litter. For instance, Prof. A. S. Packard, in 

 his work entitled " The Labrador Coast," states he was 

 informed by a native " that the white and blue fox littered 



