252 MAMMALS. 



The latter extends over the -svhole north of Europe and Asia to the Arctic Sea. It is sometimes 

 found in the south of Scotland, and even in Cumberland, and is common in the Highlands. It 

 is this species which inhabits Norway, Sweden, and the north of Russia. Nilsson has proposed 

 to divide it into other species, L. canescens and L. bokealis, both found in the south of Sweden ; but 

 the more general opinion is that these are only varieties. It stretches away thence north of 55° 

 on to Kamtschatka. Schrenck says that it is very common in Amourland and Saghalien.* 



It is also found in the AIjds in Switzerland, and in the Pyrenees, the higher parts of 

 Bavaria, and the Caucasus ; but is not found in any of the low groimds or plains between these 

 mountainous regions. This is one of the very few instances amongst Mammals of a phenomenon of 

 distribution exceedingly common among plants, — viz., of Arctic species being found on the tops of 

 high isolated moimtains or ranges of mountains, far distant from their normal boreal habitat, — a cir- 

 cumstance undoubtedly due in the case of plants to the glacial epoch. As at its recess the heat gra- 

 dually returned, and gained upon the cold, it di'ove the general army of temperate and boreal species 

 of plants and animals which had been developed under the influence of the cold, slowlj^ northwards, 

 and they, as they passed on their way, left detachments like garrisons to hold the difierent lofty 

 fastnesses through which the host retreated. These have done their duty faithfullj', — they have set 

 an example to all garrisons. Well provisioned with a constantly self-renewing store, they have held 

 each their castle through countless ages, ajsparently hopelessly cut off from the main armj', girdled 

 in on every side by an impenetrable blockade across which no straggler or emissary can hope to 

 pass, which none could enter and live. 



I believe that their enemy (heat) is slowly and gradually drawing his circum.vallation closer 

 and closer round their holds, imperceptibly straitening their communications, and if no change 

 come, wiU end in scaling the heights and exterminating the garrison, destroying aU, both old and 

 young, ruthlessly and without distinction. Ere then the war between cold and heat may undergo 

 a change. The allies of heat may desert its cause, and allow the Arctic species to recover their lost 

 ground, and liberate their long-besieged brigades. 



If tliis should ever happen, would the species, if endowed with consciousness, recognise one another 

 again when they met ? Or if they have changed, which will have changed most — whether will the 

 Polar form, which has gone on with the main body, or those left behind on moimtain-tops, be nearest 

 the tj-pical form which the common ancestor of both bore at the time thej' parted ? Probably those 

 left behind, cooped into narrower limits, and more exposed to changes, must have been most trans- 

 formed. As yet the Varying or Variable Hare, in this respect ill-named, has nothing varied. The 

 species from the North Cape, and that from Switzerland, may be laid side by side, and no differ- 

 ence be perceptible. 



The European form in winter becomes, practically, f wholly white except the tips of the ears. It 

 is the same with the Polar Hare of America ; but the black tip of the ears in winter is as absolute 

 a specific character as the black tail of the Ermine, or the black shaft of the feathers of the White 

 Willow Grouse. J 



* Schrenck, von Leopold, " Reisen uuJ For- and feathers in auimals exposed to cold. Watcr- 



schungen in Amurlaud." 1858. house ascribes the blanching of the fur to the extreme 



+ There is a slight freckling of black and yellow on cold. " I am strongly inclined to believe," says he, " that 



the bands of the ears, and the nose is yellowish. the extreme cold in such cases as the jiresent, by checking 



X It is not known what is the cause of this singular the plasmatic circulation, not only bleaches but ultimately 



exception to the effect of cold upon the colour of the fur destroys the vitality of the hairs, and that this is the 



