298 LEPORID^E— LEPUS 



high-crowned molars, straighter upper incisors, more powerful 

 masticatory muscles, and in the larger eyes, resulting in 

 heightened superciliary processes ^ and peculiar curvature of the 

 cranium. To the above features may be added the longer 

 limbs, the shorter tail, complicated system of juvenal and post- 

 juvenal pelages, and the greater number of mammae, resulting 

 in larger (in compensation for fewer) litters of young. There 

 are only three points in which the Brown Hare appears to be 

 the more specialised, namely, in its longer ears, more highly 

 developed olfactory organs, and stronger whiskers. But it has 

 been already suggested that this is only in compensation for its 

 poorer sight, a combination characteristic of a nocturnal animal. 

 Winge's suggestion that the short ears and shrunken nose 

 of true Lepus are a result of a cold climate has no weight in 

 the case of the Irish Hare, which has a southern habitat. 

 Having regard to the short ears of the Rabbit, this particular 

 feature is probably a survival of a primitive character. 



The work of differentiating the various members of the 

 group Lepus further shows that the southern forms, e.g., L. 

 hiberniciis, and, very markedly, the extinct pleistocene L. 

 anglicus, are distinctly more primitive than the more northern, 

 such as L. t. scoticus. Apart from their teeth, the 

 humerus and forearm are in the former of approximately 

 equal length, as seen also in O. cuniculus, whereas, in more 

 northern forms there obtains the specialised arrangement, 

 whereby, as in L. europceus, the radius is distinctly longer 

 than the humerus. 



The most specialised of all is Boreolepus groenlandicus, with 

 its always white woolly coat, short ears, strong nails, and 

 protruding incisors ; an animal which by no stretch of the 

 imagination could be regarded as ancestral to, or even older 

 than, the British varying hares, especially since, as shown 

 above, L. anglicus, the ancestor of the latter, is most nearly 

 allied to the modern hibernicus and not to grcenlandicus. 



There is no evidence to show how the ancestors of the 

 Greenland Hare reached their present habitat. They can 



' Note, however, that in this case the elevation of the roof of the orbit is in some 

 measure also due to mechanical raising by the longer roots of the more hypsodont 

 cheek-teeth. 



