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 (zo¢ 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 Z. xagerz 
hallucalts of southern Italy and £. drevicaudus 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, Sczence, 4th November 1898, 615-616). 
£. smithit 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 Zvotomys, as in true Lefus, 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, Avotomys 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 Lefws, its more specialised representa- 
tives have now become restricted to inhospitable arctic regions, 
mountains or islands. Like Lefus, it is older than the separa- 
