404 MURID^— EVOTOMYS 



the mountains of North Carolina and Colorado, with the sea- 

 coasts of New Jersey and Northern Carolina ; and in Europe 

 to the Pyrenees {not in Iberia), the mountains of southern Italy, 

 Rumania, and Trebizond. In Asia, it reaches the Thian-Shan 

 and Kinghan Mountains of Mongolia ; Pekin and the Shansi 

 Mountains (8000 feet) of North China ; Korea, Sakhalin, and 

 Japan, from Hokkaido (Yezo), to Kiushiu. 



Its southern habitats are usually in mountains (as E. nageri 

 hallucalis of southern Italy and E. brevicaudus of Black Hills, 

 S. Dakota), where they may be quite isolated ; and in 

 North America these detached colonies have been found 

 in what are practically cool faunal islands surrounded by 

 warmer zones far south of the ordinary range of their species 

 (see Miller, Science, 4th November 1898, 615-616). 



E. smithii is remarkable because, although a member of 

 an hypothetically " arctic " genus, abundant in the British 

 Pleistocene, and at Ightham accompanying such nominally 

 " arctic " forms as Lemmus and Dicrostonyx, it is common 

 in the two semi-tropical islands of Shikoku and Kiushiu, 

 Japan (Thomas, Proc. Zool. Soc, London, 1905, ii., 355). 

 Thus, in Evotomys, as in true Lepus, the various species may 

 be found in very different climates, so that the occurrence 

 of a member of the genus in any particular geological deposit 

 cannot in itself be regarded as evidence of climate. 



Distribution in time : — The earliest remains of the genus yet 

 discovered are those from the late pliocene Forest Bed of 

 Norfolk. Others are known from the High and earlier 

 Middle Terrace deposits of the Thames valley (lower and 

 middle Pleistocene), but all are too fragmentary for specific 

 determination. 



Origin:— As a circumpolar genus, Evotomys may be com- 

 pared with (restricted) Lepus, especially in its isolated southern 

 colonies, its absence from North Africa and presence in Japan, 

 but in the latter country it ranges much farther south than 

 Lepus. Unlike Lepus, it is a generalised type, which no doubt 

 largely accounts for its survival against the competition of 

 modern forms. Like Lepus, its more specialised representa- 

 tives have now become restricted to inhospitable arctic regions, 

 mountains or islands. Like Lepus, it is older than the separa- 



