DESCRIPTIONS OF NEW SPECIES OF MAMMALS. 789 



Characters.— A rat of somewhat leas bulk than Mus flehilis, but with 

 smaller hind foot and shorter tail, the length of latter considerably less than 

 that of head and body. Fur densely spinous, but the bristles even more 

 slender than in Mus flehilis. Colour brown throughout, the belly not distinctly 

 paler than sides, skull slender, with dorsal profile nearly straight from middle 

 of braincase to tip of nasals. Teeth small, normal. Mammae 8. 



Fur. — The fur is fine and close in texture, but on examination it is seen to 

 be densely beset with very slender spines. These spines are rather more 

 numerous than in Mus flehilis, but their width is distinctly less than in the 

 Andaman species. The fur of the back is sprinkled with a few long terete 

 hairs, but these are only evident on close inspection. On the belly the 

 bristles are reduced to mere rudiments scarcely to be distinguished from the 

 oridinary hairs. 



Colour. — Back and sides a fine grizzle of black and russet, the two colours in 

 about equal parts on the back, the russet in excess on the sides and outer 

 surface of legs, where it is faintly washed with wood brown. Belly and inner 

 side of legs drab, a little tinged with russet. Chin, middle of throat, axillary 

 region and area surrounding nipples white ; this colour perhaps abnormal. 

 Cheeks and muzzle like belly, but slightly more washed with russet. Top of 

 bead dark, grizzled hair brown. Feet scantily sprinkled with brownish and 

 whitish hairs. Ears and tail uniform dark brown. 



Tail. — The annulation of the tail is indistinct and somewhat irregular. 

 At middle there are eleven or twelve rings to the centimetre. From the 

 base of each scale spring two or three stiff hairs, the length of which scarcely 

 exceeds the width of the rings. The hairs are very inconspicuous, and more 

 apparent to the touch than to sight. At extreme tip the skin of the tail is 

 whitish, but this character may readily be abnormal. 



Mammce. — There are 8 mammae, 1 pectoral pair and 3 inguinal pairs. 

 Feet. — Relatively to the size of the animal, the feet are unusually small and 

 weak. Soles with the six pads rather indistinct in tbe dry specimen. 



Ears. — The ears are in no way peculiar. In length they are about equal to 

 distance between eye and muzzle. They are naked, except for a fine, almost 

 microscopic pubescence. 



Skull. — The skull of Mus pulUventer differs conspicuously from that of the 

 other Andaman and Nicobar rats in its flat dorsal outline. When viewed 

 from the side the profile is nearly straight from front of nasals to middle of 

 braincaae. The palatal profile shares the same peculiarity but to a less 

 degree. Except for its flatness the skull closely resembles that of Mus rattus. 

 The rostrum is, however, more elongate, and the audital bullse are smaller. 

 When viewed from above, the plate forming outer wall of antorbital foramen 

 scarcely extends in front of line of outer curve of zygomatic arch, while in 

 Mus rattus it projects conspicuously in front of this line. Viewed from the 

 side this plate is narrower and less concave than in Mus rattus, and its front 

 edge is nearly straight. 



