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tially spineless. Tail about as long as head and body, dark brown 

 throughout, its annulation more coarse that in M. bowersi. Ear short and 

 broad, its length. less than distance from eye to nostril. Skull and teeth 

 much heavier than in the Burmese species, the rostrum shorter, broader 

 and deeper, and supraorbital ridges remarkably heavy. Enamel pattern of 

 third upper molar essentially like that of second, and both with well developed an- 

 tero-external tubercle. 



Far. Although the fur is composed of the usual three kinds of hair 

 the bristles are so slender that to the unaided eye their true nature is not 

 apparent. They average about 30 mm. in length on the back, while the 

 terete hairs are little more than half as long. 



Color. Back and sides a fine grizzle of black and dull buff (slightly 

 browner than Ridgway, PI. V, No. 13), the two colors nearly equally 

 mixed on back, but the black hairs much less abundant on sides, where 

 the buff is somewhat dulled by the irregular appearance at the surface 

 of the gray (Ridgway, PI. II, No. 7) underfur. Underparts cream buff 

 to base of hairs, this color extending down inner surface of legs to wrists 

 and nearly to ankles. Feet scantily clothed with short sepia hairs. 

 Head like back, but the colors more closely blended. Cheeks like sides. 

 Muzzle hair brown. Ears and tail dark brown, the latter without trace 

 of paler tip. 



Tail The moderately long tail is coarsely conspicuous and uniformly 

 annulated. At middle there are about 9 rings to the centimeter. The 

 rings are noticeably divided by cross furrows into scales slightly longer 

 than broad, the distal edges of which are crenulate. Numerous stiff 

 black hairs spring from beneath the free edges of the rings, usually three 

 to each scale. In length the hairs about equal the width of the rings. 

 At tip of tail the rings become closer and the hairs longer and less stiff 

 but without forming a pencil. 



Skull. The skull of Mus validus (Pis. Ill and IV, Fig. 1) differs more 

 widely from that of M. bowersi (Pis. Ill and IV, Fig. 4) than could be an 

 ticipated from the external similarity of the two animals.* The latter 

 in fact bears a superficial resemblance to the skull of Mus vociferans, dif 

 fering chiefly in its more slender rostrum, larger audital bullre, more 

 convergent zygomata, and obsolete supraorbital ridges, characters all but 

 one of which are directly the opposite to those of Mus validus. Supra- 

 orbital ridges very prominent, and forming a distinct postorbital angle, 

 behind which they are continued backward along sides of braincase to 

 extremities of interparietal. The lower portion of the antorbital fora 

 men, widely open in Mus bowersi, is here reduced to a mere slit, partly 

 as the result of shortness of rostrum and consequent unusually close con 

 tiguity of root of incisor and anterior edge of outer wall of foramen. 

 The plate forming this outer wall is broad, its outer surface distinctly 

 concave. Anterior border strongly convex from a little below middle, 



*For the opportunity to examine a specimen of Mus bowersi collected 

 by Fea at Yado, Burmah, I am indebted to Dr. R. Gestro, of the Genoa 

 Museum. 



