DESCRIPTIONS OF NEW SPECIES OF MAMMALS. 793 



Mus BURKDLUS, new species. 



Tijpe.—hdvAt male (skin and skull), No. 111817, U. S. N. M. Collected on 

 (Jar Nicobar, January 25, 1901, by Dr. W. L. Abbott, Original number, 865. 



Characters, — Similar to Mus burrus, but much smaller ; hind foot, 38 ; 

 greatest length of skull, 41. 



Colour. — The colour and other external characters so closely resemble those 

 of Mus burrus as to need no detailed description. 



Skull. — The skull though diifering from that of Mus burrus chiefly in its 

 smaller size is also distinguishable by its much more slender rostrum, a cha- 

 racter which is in no way due to differences of age. The outer margin of the 

 nasal is straight, as in the larger animal. 



Teeth. — The teeth are similar to those of Mus burrus, though perceptibly 

 smaller throughout. 



Measurements. — External measurements of type : Total length 357 mm. • 

 head and body, 174 ; tail, 183 ; hind foot, 38 ; ear from meatus, 19 ; ear 

 from crown, 15 ; width of ear, 15. 



Cranial measurements of type : Greatest length, 41 mm. ; basal lenoth 

 37'4 ; basilar length, 34'8 ; length of nasals, 15 ; combined breadth of nasals 

 4 ; zygomatic breadth, 19'8 ; interorbital constriction, 6*8 ; maxillary toothrow 

 (alveoli), 7, 



Specimens examined. — One, the type. 



Remarks. — Although represented by only one specimen, the rat of isolated 

 Car Nicobar is evidently distinct from those of the larger southern islands. 

 That its small size is not due to immaturity is shown by the fact that the 

 type is fully adult, with distinctly worn teeth, a much older individual than 

 several of the specimens of Mus burrus. 



Mus BURRESCENS, new species. 



Type.— Mult female (skin and skull). No. 111789, U.S.N.M. Collection 

 on Great Nicobar Island, March 12, 1901, by Dr. W, L, Abbott, Original 

 number, 926, 



C^arac^ers.— Externally similar to Mus burrus, but red of upper parts a little 

 more intense. Skull distinguishable from that of the related species by the 

 form of the nasal bones, which are strongly contracted a little in front of 

 middle. 



Colour. — The upper parts are slightly more red than in Mus burrus, and 

 the grizzle produced by the black hair-tips is less coarse, differences easily 

 appreciable on comparison. Otherwise the two animals are entirely similar 

 so far as external characters are concerned. 



Skull. — The skull is like that of Mus burrus, except in the form of the nasal 

 bones. The outer margin of each nasal, straight or nearly so in Mus burrus 

 is here abruptly concave at middle. The result is a spatulate outline of the 

 two nasals together, quite different from the regular cuneate form character* 

 istic of Mus burrus and Mus burrulus. 

 Teeth. — Teeth as in Mus burrus. 



