FLESH-EATING MAMMALS 19 



sheen, which explains the term "blue fox" so often met with in 

 accounts of polar voyages, while in winter it is of a snowy-white. 

 Desert animals make an approach to the desired end of invisi- 

 bility by means of a uniform fawn or buff colour, and this is the 

 case with the little Fennec {Cams zerda), a long-eared fox in- 

 habiting the Sahara (see vol. i, p. 93). 



Bear Family, &c. 



The last great section of the terrestrial Carnivora is the one 

 which includes Bears and many allied forms. Bears are for the 

 most part very mixed feeders, but the Polar Bear (Ursus arctos), 

 which is the largest of them, is essentially a flesh-eater, though it 

 devours vegetable matter to some extent, when such is available. 

 This huge creature is the biggest living Carnivore, and old males 

 have been known to attain a length of over 8 feet and a weight of 

 some 900 pounds. To maintain so vast a bulk means an enor- 

 mous quantity of food, regarding which Sergeant Francis Long 

 of the Greely Arctic Expedition remarks (in The Big Game of 

 North America): — "About four hours each day is the longest 

 time he allows himself for rest from his patient and persevering 

 search for food, for his cavernous maw and his voracious appetite 

 tax his skill and time to keep them supplied with fish and flesh. 

 In his hunt for game the night as well as day is favourable to 

 him, the reflection from the ice at night being sufficient light to 

 enable him to sight and steal upon his prey. The seal is the 

 chief source of food for the Polar Bear, though he also preys 

 upon the walrus and on various fishes." Unlike the Arctic Fox, 

 the Polar Bear is always white or yellowish white, and indeed a 

 change of colour is unnecessary, for he spends his whole time 

 surrounded by snow and ice. This must be looked upon as a 

 case of aggressive general coloration pure and simple, for, ex- 

 cepting man, this monarch of the Arctic regions has no enemies 

 capable of injuring him. In stalking such wary creatures as seals, 

 the inconspicuousness due to the white coloration is invaluable, 

 and the Bear is also greatly helped in this pursuit by the fact that 

 the under sides of his feet are thickly covered with fur, which not 

 only prevents slipping, but also conduces to noiselessness. Marked 

 powers of swimming and diving confer additional advantages. 

 Many accounts have been given of the cunning with which this 



