234 MR. 0. THOMAS ON THE [Apr. 16, 
head 18, breadth 18; heel to front of last foot-pad 23; length of 
last foot-pad 7:0. 
Skull: tip of nasals to centre of fronto-parietal suture (“ bregma’’) 
36 millim.; nasals, length 21, greatest breadth 6:0; interorbital 
breadth 7:7 ; outer wall of infraorbital foramen, length 4-7 ; palate, 
length 26:5; length of palatal foramen 7:9; diastema 13:6; length 
of upper molar series 9:4. 
Dimensions of a fine female in spirit, preserved in the Museo 
Civico, Genoa :—Head and body 230; tail 393; hind foot 49; ear 
20; heel to front of last foot-pad 25 ; length of last foot-pad 8°8. 
This spirit-specimen was obtained by Signor Beccari at Sungei 
Bulu, W. Sumatra, thus affording another instance of the relationship 
between the mountain-faunas of Sumatra and Borneo. Its examin- 
ation, which I owe to the kindness of my friend the Marquis of 
Doria, has enabled me to add certain particulars, only observable in 
spirit-specimens, to the original description of this species. 
Mus sabanus belongs to a well-marked group of Rats which contains 
Mus jerdoni, Bly., M. niveiventer, Hodgs., M. coxingi, Swinh., M. ed- 
wardsi, Thos., M. heliwaldi, Jent., M. alticola, Thos., and others. 
These species are, however, all very much smaller than it is, with one 
exception, M. edwardsi, which is as much larger, and not one of 
them has a tail of anything like the extraordinary length of that of 
Mus sabanus. 
One species, indeed, also a native of Borneo, has a certain super- 
ficial resemblance to the present one, although belonging to quite a 
different group of Rats. This is WZ. muelleri, Jent., of about the same 
size, and with a nearly equally long tail; but it may be readily 
distinguished by its coarse Mus decumanus-like fur, yellowish instead 
of rufous coloration, the less sharply defined white underside, and 
by the quite uniformly brown-haired feet and tail. 
16. Mus LEprurus, Jent. 
a. Ad. 
b. Imm. 3000 feet. 24/3/88. 
Described by Dr. Jentink from Javan examples now in the Leyden 
Museum. ; 
17. Mus auticouta, Thos. Ann. Mag. N. H. (6) ii. p. 408 
(1888). 
a,b. § 2. 8600 feet. 24/2/88. 2. Type. 
Fur mixed with flexible spines both above and below. General 
colour above a peculiar bluish grey, not speckled or grizzled, darker 
along the median line. Dorsal hairs and spines creamy white 
basally, gradually darkening to grey terminally. Underside pale 
yellowish white, the hairs and spines uniformly of this colour to 
their bases , the line of demarcation on the sides not very sharply 
defined. Hands and feet white, the hairs short and fine, fifth hind 
toe (without claw) reaching nearly to the end of the first phalanx 
of the fourth. ‘Tail finely rmged, the rings averaging about 10 or 
