214 SOME CHINESE VERTEBRATES. 
Zappey did not find any representative of the subgenus Caryomys (Thomas, 
1911, p. 175), four species of which are now known, alcinous, inez, nux, and eva. 
Microtus (HEoTHENOMYS) MUCRONATUS, Sp. NOV. 
Type:— Skin and skull No. 7789 M. C. Z., female adult, from Tachiao, 
western Szechwan, at an altitude of 12,000 feet. August 11, 1908, Walter R. 
Zappey. 
General Characters:— A large Eothenomys, with larger ear and hind foot, 
browner color, longer and fuller pelage than M. melanogaster. Skull larger 
than that of M. aurora with distinctly bowed zygomata, broader muzzle, and 
with deeper palatal grooves and a prominent median spine at the posterior edge 
of the bony palate. Third upper molar with but six prominent angles and its 
posterior heel nearly bilaterally symmetrical. 
Color: — Entire upper surface of the body a fine grizzle of blackish hairs 
and hairs with cinnamon-rufous tips, producing a general ‘‘mummy brown” 
tone. The bases of the hairs are dark slaty black, with the cinnamon-rufous 
confined to a space of a millimeter or two at the tip. Under a lens, many of these 
rusty-tipped hairs are seen to have a very fine darker point. The lower surfaces, 
including the upper lips and base of the nose are dark slate color with a very 
slight buffy wash between the fore legs. Feet and tail covered with short hair- 
brown hairs, those of the latter slightly paler ventrally. 
Skull: — In general appearance the skull is like that of a large M. melano- 
gaster but the zygomata are more bowed. The palatal region shows several 
striking peculiarities. The palatal grooves, which in melanogaster are so shallow 
as to be scarcely appreciable, in mucronatus are deep and conspicuous, running 
one from each of the incisive foramina to near the posterior edge of the palate, 
where in both species they end in two pit-like perforations. The bony palate 
instead of ending in an evenly truncated shelf, has a prominent median spine 
as in M. chinensis of the related subgenus Anteliomys. The lower jaw is very 
massive and strikingly broad in side view as compared with M. aurora and M. 
melanogaster. 
The teeth are essentially as in the latter species, but much heavier through- 
out (Figs.C,D). The first upper molar shows the usual large anterior transverse 
prism succeeded by three closed triangles and a posterior enamel space which is 
formed by the confluence of two small folds of opposite sides, the outer of which 
is slightly in advance of the inner. There are thus three external and four 
Om 
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