568 



THE CARNIVORES 



increase in number, at the same time as the tips of the other hairs become white, 

 until the whole length of each hair is of that color. The animal is then completely 

 clad in white, the naked tip of the nose being, however, black, while in certain cases 

 the extremity of the tail may also be black. A specimen in the pure white winter 

 dress is represented in the foreground of our second illustration. This winter 

 change of color is, however, by no means of constant occurrence ; gray hairs some- 

 times largely mingling with the white, while at other times the prevalent hue of the 

 fur is a uniform bluish gray, as shown in the upper figure of our second illustration. 

 Moreover, occasionally, pure white foxes are to be met with in summer. In Ice- 

 land, where the winter is less severe than in the more northerly regions, the winter 



ARCTIC FOX IN SUMMER DRESS. 

 (One-eighth natural size.) 



dress of the Arctic fox is nearly similar to the summer one, so that these animals 

 are ' ' blue ' ' at all seasons. 



The assumption of a white dress in winter is in order to assimilate the color of 

 the animal to that of the snow-fields among which it dwells, and it is somewhat diffi- 

 cult to understand why the change does not invariably take place in the more north- 

 ern regions. The hair clothing the soles of the feet is to aid the creature in obtain- 

 ing a sure foothold on frozen snow and ice. 



According to Richardson, Arctic foxes, which were formerly abundant on the 

 shores of Hudson's Bay, dwelt there in small colonies of from twenty to thirty bur- 

 rows each. During the autumn and winter such of these foxes as inhabit the more 

 northern districts of Arctic America undertake a southerly migration, keeping as 

 much as possible to the coasts, and the length of the migration depending to a con- 

 siderable extent whether the line of the coast coincides with the line of march 



