212 SOME CHINESE VERTEBRATES. 
General Characters:— Larger than M. (Hothenomys) melanogaster, pelage 
long and soft, ears rather small. Color reddish brown above, and dark slate 
washed with brownish below. Skull large, with rather prominent postorbital 
shelf-like ridges; teeth essentially as in M. melanogaster, but the third upper molar 
longer and with a long, narrow external heel. 
Color:— Dorsal surface of body, forehead, and cheeks, nearly “‘tawny”’ 
of Ridgway, with peculiar bright yellow brassy reflections. The individual 
hairs are about 11 mm. long, dark slate-black except at the tips which are tawny 
to tawny-ochraceous; mixed with these hairs are others of the same fine texture 
but slaty black throughout, so that a general tawny appearance is produced in 
which the black is less conspicuous than in those species that have the black hairs 
longer than the general body hairs. The muzzle isa grizzled gray: without tawny. 
Sides of the body hardly lighter than the back, the color grading insensibly into 
that of the ventral surface which is gray washed conspicuously, except on the 
thighs and throat, with ochraceous buff. The slaty bases of the hairs show 
through everywhere so as to darken the grayish of the belly but not to such 
an extent as to produce the blackish seen in 
the ventral surfaces of M. melanogaster. 
Tail covered with short blackish hairs 
above, which become slightly grayish below, so 
that the tail is indistinctly bicolor. Feet with 
short brown hairs, nearly Prout’s brown, with 
grayish reflections. The short round ears are 
thinly covered with minute hairs of a similar 
color. 
Ve 
Skull:— Compared with that of M. melano- 
yaster, the skull is larger and heavier, with more 
prominent ridges and angles. The postorbital 
A) processes protrude as narrow shelf-like ridges, 
B 
A 
and the zygomata are stouter and more bowed. 
Microtus (Eothenomys) aurora. Type 5 i 
No. 7788. A, Enamel pattern of right Lhe palate is marked by two shallow longi- 
upper molars; B, Enamel pattern of t¢ydinal grooves that end posteriorly each in a 
right lower molars. 5 7 
deep pit or perforation of the palate. The 
hinder margin in the type is practically straight across, though in another speci- 
men it is slightly protuberant medially, yet not forming a spinous process. 
The enamel pattern of the first upper molar (Figs. A, B) consists of four 
closed triangles, succeeded by a fifth space in which the two folds of opposite 
