480 MR. O. THOMAS ON THE MAMMALS [DeC. 4, 



length 24, greatest breadth 8*2; interorbital breadth 1 1-1; uiter- 

 parietal, length 68, breadth 125 ; depth of anterior zygoma-rO)t 

 /•8 ; palate, length 36-3, breadth outside m." 13-1, inside m/ 5-6 ; 

 length of palatal foramina 7"0; length of upper molar series 12"0. 



The most remarkable thing about this Rat is its gigantic size, 

 there being only two Rodents at all alhed to it, viz. Nesokia bandicota 

 and Cricetomys yamhianus, which equal it in this respect. Its 

 relations to its only really close ally, Mus rex, are noted below. 



Its habits, according to Mr. Woodford, are entirely terrestrial. 



19. Mus REX, Thos. (Plate XXII. figs. 4, 5.) 



Mus rex, Thos. I. c. 



a-d. 2 d and 2 ? . [7.] 



Size very large, although markedly less than in the last species. 

 Colour, character of fur, lengths of ears, proportions of toes, and 

 number of mammae all quite as in that species. Sole-pads (Plate XXII. 

 fig. 5), however, much larger and broader, less sharply defined. Tail 

 exceedingly long, longer than the head and body combined, naked, 

 scaly, the scales not overlapping, but forming prominent projections, 

 which give to the whole tail an extraordinary roughened rasp-like 

 character, most marked, however, on the underside, and gradually 

 fading off towards the tip. These projecting scales are arranged in 

 rings, which average from 7 to 9 to the centimetre. The base of 

 the tail is hairy like the body for about one inch. 



Skull (Plate XXII. fig. 4) strong and stout, the zygomata propor- 

 tionally more expanded than in M. imperator . Tips of nasals not 

 projecting in front beyond the level of the front of the incisors. 

 Frontal processes of premaxillsB scarcely extending backwards beyond 

 the nasals. Supraorbital edges square and sharp, not beaded. Inter- 

 parietal bone absolutely, as well as relatively, larger than in M. impe- 

 rator. Outer plate of anterior zygoma-root markedly projecting 

 forwards. Palatal foramina and bullae as in the last species. 



Teeth as in Mus imperator, but the last upper molar rather larger 

 in proportion. 



Dimensions (in spirit) : — 



Heel to front Last 

 Head and Tail. Hind foot. Ear. Forearm of last foot-pad, 

 body. and hand, foot-pad. length. 



6 {type) 290 296 55 18 76 30-2 16-3 



6 280 300 57 16 76 30-5 16-5 



2 270 285 54 16 73 29-5 15 



2 255 277 54 14 73 30 16 



Skull ( J ) : — Basal length 54 millim.,- greatest breadth 33 ; nasals, 

 length 20, greatest breadth 6'8; interorbital breadth 9; interparietal, 

 length 7"0, breadth 13"2 ; depth of anterior zygoma-root 7'0 ; 

 palate, length 33, breadth outside m.^ 11-3, inside m.^ 5'0 ; length of 

 palatal foramen 6'8 ; length of upper molar-series 1 1'l. 



Habits entirely arboreal {fide Woodford). 



I am quite unable to say to which of the known species of Mus these 

 two large Rats are most nearly allied. While clearly differing from 



