182 Messrs. O. Thomas and M, A. C. Hinton on the 
for another place, it may be mentioned that the features 
common to the three genera just named suggest, for each of 
them, descent—in directions more or less divergent—from 
the remarkable late Pliocene Kuropean genus Jdimomys ; 
and no character-in any one of the other three living genera 
seems to be incompatible with such a view of their origin. 
Voles of the genus Phaiomys are confined to the highlands 
of Central Asia, where they are widely distributed, occurring 
always at high altitudes and most frequently in close associa- 
tion with the banks of streams. ‘The species show two well- 
marked types of coloration—some, like P. lewcurus, being 
pallid and sandy, others, like P. waltoni, darker and greyer. 
With regard to the material collected by the Expedition, 
we are, at present, unable to find any reliable character which 
will serve to distinguish the specimens from Tinki Dzong 
and Tingri from 2. leucurus, which was originally described 
from the mountains above 'T'so-Moriri, Ladak. It is, how- 
ever, quite possible that the Tibetan animal will prove to be 
distinet from true lewewrus. The series from Tingri, long as 
it is, is insufficient for the purpose, owing to the fact that so 
many of the skulls collected have been smashed by the traps. 
It may be recorded that the mammary formula in the two 
females is 2—2=8, and that the pelage of the young 
approaches that of the adults of the next species in colour, 
being far darker and less sandy than in adult leucurus. 
“ Hound in colonies in sand.”—A. I’. 2. W. 
6. Phaiomys everesti, sp. n. 
gd. 61; 9. 49. East Everest, 17,000’, 9th and 18th 
September, 
A “‘orey” species, closely related to P. wal/on?, but con- 
siderably smaller. 
Size small (hind foot to 18, condylo-basal length not much 
exceeding 27 mm.). 
External characters and colour as in P. waltoni, but tail 
light above and below, instead of being more or less 
bicolored ; upper parts of a rather dark earthy grey, very 
different from the sandy tints of P, leucurus. Mamme 
2—2=8 
Skull and teeth essentially as in other species of the 
genus, Skull rather lightly and delicately built with small 
flattened bulle ; the latter rather smaller than in waltoni, 
and differing conspicuously from the large and inflated bullee 
of leucurus. 
. 
