28 
FASCICULI MALATENSES 
The specimen of Mus pellax in the British Museum is practically a topo- 
type of M. jerdoni^ but, as I have stated elsewhere, until the skin and skull of 
Blyth’s M. jerdoni can be closely compared with specimens of M. pellax and 
M. bukit^ the matter cannot be definitely settled. The skulls, however, of 
these last two species being so distinct there should be no difficulty in deciding 
the question, even though the type is young. 
48. Mus rufescens, Gray. 
(Plate IV, fig. 3). 
Mus rufescens. Gray, Charlesw. Mag. Nat. Hist, i, p. 585 (1837) ; Bonhote^ 
P.Z.S. 1900, p. 878. 
Mus rattus, (Linn.), Flower., P.Z.S. 1900, p. 361. 
a, b. ^ , 9 ad. Biserat, Jalor. 4th July, 1901. 
In external appearance these specimens agree well with the most common 
form of the rattus group found in the Peninsula ; the skull, however, is 
distinguished by having very small teeth. As, however, I find a certain amount 
of variability in the size of the teeth in a series from Siam and the Peninsula, 
I presume it is merely a question of individual variation. 
49. Mus jalorensis, sp. nov. 
(Plate II, figs. I and 2, and Plate IV, fig. 4). 
A medium sized short tailed rat of the Mus rattus group. 
Fur moderately long and soft, thickly interspersed with very slender 
spines. General colour warm grizzled brown, becoming greyer on the flanks. 
Each hair is ashy-grey at the base with a broad brownish tip, the spines are whitish 
with a black tip, and there are also some long black hairs. Under parts pure 
white, sometimes with a slightly yellowish tinge, the line of demarcation between 
the upper and under parts being well marked. Feet, dark brown. The tail 
hardly exceeds the head and body in length, and is uniformly dark throughout, 
and scantily clothed with very short stiff hairs. 
Skull. Similar to that of Mus rufescens from the Malay Peninsula, but 
smaller and narrower. The nasals taper greatly towards their posterior end. 
The supraorbital ridges end altogether or become inconspicuous about the 
middle of the parietals. Viewed from below, except for being narrower and 
more slender, the skull does not offer any very striking points of difference. 
The bullae are rather more rounded and do not appear to stand out quite so 
much from the base of the skull. 
Dimensions of type (measured in the flesh : — Head and body, 144 mm. ; 
Tail, 177 mm. ; Hind foot, 31*5 mm. ; Ear, 19 mm. 
