TWO FASHIONABLE FURS ait 
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 Canzs 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 
