210 SOME CHINESE VERTEBRATES. 
M. cansus they differ in smaller size, and from the recently described M. rufes- 
cens in this and certain cranial characters as noted by Dr. J. A. Allen (1909). 
The measurements of the two specimens as taken by the collector are: — 
No. Sex. Total Length. Tail. Hind Fool. 
7130 2 193 38 31 
7131 rot 190 35 27 
The skulls show that the two specimens are nearly comparable in age, yet 
that of the female is the smaller. Thomas has pointed out the fact that the 
skulls of /. cansus show a sexual differentiation of a similar nature, those of the 
males being markedly the larger. The dimensions of the two skulls follow, 
those of the male in each case first: — greatest length, 39, 37; basal length, 
33.5, 31; palatal length, 21, 19.5; diastema, 11.3, 11.2; zygomatic breadth, 
26.5, 24.4; interorbital constriction, 8, 8;~mastoid breadth, 21.8, 18.5; median 
length of nasals, 14.4, 13.5; mandible from condyle to tip of incisor, 27.2, 25.8; 
upper molar row, 9.5, 8.4; lower.molar row, 10, 9. 
Microrus MANDARINUS (Milne Edwards). 
This rare mouse is represented by six skins and skulls, three from Ramala 
Pass (at 16,000 feet) and three from Shuowlow (13-15,000 feet), in western 
Szechwan on the border of Tibet. Milne Edwards described this field mouse 
from Chinese Mongolia where it was obtained by Pére David. His figure and 
description of the exterior (Recherches hist. nat. mammiféres, 1868-74, p. 129, 
pl. 12, fig. 4) probably refer to a highly colored specimen as none of the five 
studied is so brightly ochraceous as he indicates, though in other respects the 
agreement is close enough. In his figures of the teeth on plate 13, the figures 
4c and 4d are interchanged, being the lower and upper molar series respectively. 
All our specimens agree in color, having the dorsal surfaces a finely grizzled 
mixture of ochraceous and black-tipped hairs, the lower surfaces gray, with 
plumbeous bases to the hairs. The tail is short and bicolor like the body. 
The measurements in the flesh of five specimens are: — 
No. Length. Tail. Hind Foot. 
7793 ~ 120 28 17 
7794 123 23 16 
7795 119 23 16 
7796 125 24 16 
7797 134 27 17 
The skull of No. 7796 measures: — total length, 23 mm.; basal length, 21; 
palatal length, 13; zygomatic breadth, 13.6; interorbital constriction, 3.7; 
