TWO FASHIONABLE FURS 211 



though they had been cropped), moderately sharp muzzle, 

 very long and bushy tail, and the coat of hair on the 

 soles of the feet. From this latter feature the species 

 takes its name of Canis lagopus; the object of the hairy 

 soles being, of course, to afford the animal a firm foothold 

 on the ice and frozen snow on which it passes so much 

 of its time. In having two distinct colour-phases at all 

 seasons of the year, which may be met with in the same 

 locality, the Arctic fox stands practically unique among 

 mammals. It is true that black-maned and yellow-maned 

 lions may be occasionally met with in the same litter, 

 while black leopards and black jaguars occur now and then 

 among litters of cubs of the ordinary colour. But neither 

 of these instances is exactly on all fours with the case 

 of the Arctic fox. With regard to the lion, it has now 

 been ascertained that the black-maned and tawny-maned 

 specimens belong, in most cases at any rate, to distinct 

 local races; and it is most probable that when light- and 

 dark-maned cubs are met with in the same litter, it is due 

 to crossing between two of these races. Black or melanistic 

 leopards and jaguars, on the other hand, are more analogous 

 to albinoes, and generally occur in hot and damp climates. 

 The black phase of the common water-vole, found high up 

 in many British valleys, is an instance somewhat analogous 

 to that of black leopards, being apparently due to climatic 

 conditions, and therefore not strictly comparable with the 

 case of the Arctic fox. 



Many invertebrate animals exhibit two or more distinct 

 phases — generally differing to a certain extent from each 

 other in details of form or structure — and to such the 

 name of dimorphic animals is technically applied. Natural- 

 ists have agreed to designate the Arctic fox by the same 

 title, although, were it not that it might be taken to 



