NO. 1317. MAMMALS OF NORTHWEST SUMATRA— illLLER. 467 



rather closely resembles in color. In the tj^pe specimen there is an 

 almost naked area about 4 mm. wide and 70 mm. in length extending 

 along- median line of belly to posterior portion of chest. It has the 

 appearance of a normal character. 



Color. — Upper parts and outer surface of limbs ecru-drab, irregu- 

 larly tinged with l)roccoli-brown and clouded, particularly along middle 

 of back, by the blackish long hairs. Both under fur and long hairs 

 have a distinctly gloss}- texture, which causes much variation in the 

 exact shade as the skin is viewed in difi'erent lights. Cheeks light 

 broccoli-brown. Whiskers shining black. Underparts and inner sur- 

 face of limbs cream-buff, the line of demarcation between this color 

 mid that of sides fairly well detined. Feet dirty whitish, shaded with 

 ecru-drab, this color extending around heel. Ears blackish. Tail 

 blackish throughout basal fourth, the rest white. 



Tail. — The tail shows no peculiarities of importance. It is distinctly 

 and uniformly annulated, about 11 rings to the centimeter at middle. 

 The rings are not very clearly divided into scales except toward base. 

 Beyond middle the rings become much more closelv crowded, ])ut they 

 retain their distinctness to extreme tip. On basal fourth the hairs 

 which spring from between the rings are too minute to cause any con- 

 cealment of the annulation, but beyond this region they increase in 

 length and slightly obscure the outlines of the rings. At tip they are 

 about 5 mm. long. 



JEJars. — The ears are of moderate size and normal form. Laid for- 

 ward they extend about to eye. The surface of the ear is naked, 

 except for a sprinkling of minute blackish hairs. 



SkuN. — The skull is in size and general form not unlike that of a 

 large house rat. The brain case, however, is less deep, the audital 

 buUpe are much smaller, the incisive foramina are shorter, the nasals 

 flaro abruptly anteriorly, and the plate of the maxillary which forms 

 outer wall of antorbital foramen is not produced forward beyond 

 level of upper zygomatic root. The most striking differences are 

 found in the interorbital region. In general contour this region is 

 much as in 3fi/s norveglcus, but the supraorbital beads are developed 

 into upturned blade-like ledges between which the main surface of the 

 frontal lies at the bottom of a distinct trough. A similar condition is 

 suggested by some skulls of very aged members of the Mus surifer 

 group and by those of species of Tylomys. 



Teeth. — Incisors as in Muh narvegicus, except that those of the upper 

 jaw are a little less strongly curved. Molars (Plate XVIII, tigs. 4 and 5) 

 slightly larger than those of the house rat. Fh\st np2)er moJiir: The 

 anterio]- ridge contains three distinct cusps, the outermost of which is 

 nearly as large as the innermost and situated distinctl}' farther forward. 

 As a result, the outer side of the tooth appears longer than the inner — 

 the exact opposite to the condition in JIus. Between central and inner 



