LEPUS 299 



hardly have crossed over from Europe, since, as shown above, 

 the Greenland Hare is not at all closely allied to any Old 

 World species. It stands by geographical position farthest 

 away from the centre of distribution of the whole family, 

 and exhibits the highest expression of that specialisation 

 which has its beginning in L. hibernicus and L. anglicus. 



The origin of the varying hares of Britain, and the bearing 

 of their present distribution upon former land connections, has 

 engaged a considerable amount of attention. Most writers 

 regard them as animals of northern origin which were driven 

 south by the rigour of the glacial period. They suppose that, 

 when the cold passed away, and their southern habitat became 

 once more temperate, the hares returned north to their original 

 home. A few isolated colonies remained behind ; in mountain- 

 ous regions, the severer climate of which is presumed to have 

 suited them, and in Ireland, which is considered to have 

 become an island before the close of the glacial period, thus 

 cutting off their retreat. The above view is so plausible and 

 at first sight explains so many of the facts, that it was until 

 recent years very widely accepted ; but latterly it has been 

 subjected to considerable criticism. Thus Scharff {Proc. Roy. 

 Irish Acad., ser. III., iv., 3, 1897, 470-71 ; European Fauna, 

 i899> 315 ; European Animals, 1907, 39), while accepting their 

 northern origin, which he further supports in Distribution and 

 Origin of Life in America (191 1, 10), pointed out that the 

 hypothetical objection of the varying hares to a temperate 

 climate cannot be the cause of their supposed preference for 

 arctic and mountainous regions, since their Irish representative 

 flourishes in a country of mild temperature and comparative 

 absence of snow.^ Accordingly he suggested that the Brown 

 and Blue Hares are mutually antagonistic animals, the former 

 and stronger of which has prevailed over the weaker. This is, 

 so far as it goes, a reasonable hypothesis, and explains to a 

 certain extent the distribution of the two groups, as it existed 

 before man's interference. 



It is no doubt correct to say that the varying hares of 

 Europe and Asia form an ancient group not necessarily of 



' Hinton {Proc. Geol. Assoc, xx., 1907, 39, etc.) drew attention to a similar 

 instance in the case of one of the snow-mice, Microtus lebrunii of Crespon. 



