Miller Mammals from Lankawi and Butang Islands. 189 



Mus surifer flavidulus subsp. nov. 



Tint?. Adult female (skin and skull), No. 104,330 United States Na 

 tional Museum. Collected on Pulo Lankawi, December 4, 1890. Origi 

 nal number 109. 



Characters. Smaller than Mus surifer surifer from Trong, Lower Siam; 

 tail usually a little shorter than head and body; ground color of sides 

 and upper parts yellower (less tawney) than in the mainland form, and 

 dark shading less conspicuous; belly cream-buff instead of white: skull 

 smaller than that of the typical race, the braincase smaller and less 

 ridged. 



Color. The color is as in true Mus surifer except that throughout the 

 pelage there is a stronger tendency to yellowish tints. Ground color 

 of sides and back light orange-buff, rarely as deep as in the Trong 

 animal, which often approaches tawny-ochraceous. Underparts pale 

 cream-buff or yellowish white. The dark brown hairs of the upper- 

 parts are distributed as in Mus surifer surifer; but they appear to be 

 fewer in number. Feet and tail as in the mainland animal, the latter 

 sharply bicolor nearly to tip, its distal extremity whitish above and 

 below. 



tfkull <ntd teeth. Skull distinctly smaller than that of Mus surifer, and 

 in general of much the same form. The braincase is, however, broader 

 in proportion to the length of the skull, and the supraorbital ridges are 

 less conspicuously developed. The interparietal is similar to that of the 

 mainland animal and does not approach the peculiar triangular form 

 found in the representative of the species occurring on the Butang 

 Islands. 



Teeth as in typical Mus surifer. 



Measurements, External measurements of type: total length, 355; 

 head and body, 197; tail vertebrae, 158; hind foot, 37.6: hind foot with 

 out claws, 36. Average of ten specimens including the type: total 

 length, 335 (305-369); head and body, 175 (159-197); tail vertebra?, 160 

 (14(5-172); hind foot, 39 (37-42): hind foot without claws, 37 (36-40). 



Cranial measurements of type: greatest length, 44; basal length, 37; 

 basilar length, 34.8; palatal length, 18; least width of palate between 

 anterior molars, 5; diastema, 12.6; length of incisive foramen, 6.4; com 

 bined breadth of incisive foramina, 3.6; length of nasals, 17; combined 

 breadth of nasals, 5; zygomatic breadth, 20; interorbital breadth, 7; 

 mastoid breadth, 15; breadth of braincase above roots of zygomata, 17; 

 depth of braincase at front of basioccipital, 11; frontopalatal depth at 

 posterior extremity of nasals, 10; least depth of rostrum immediately 

 behind incisors, 7.8; maxillary toothrow (alveoli), 6.8; width of front 

 upper molar, 2.2; mandible, 23.6; mandibular molar series (alveoli), 6.6. 



Speciwi'iix examined. Thirteen skins, twenty skulls, and one specimen 

 in alcohol, all from Pulo Lankawi. 



Remarks. By its small size and yellowish color this race is readily 

 distinguishable from that of the mainland as well as from that of the 

 nearby Butang Islands. 



