182 Mr. O. Tliomas on Three new African Muridse. 



Mus Burtoni, sp. n. 



Size rather small, form slender and delicate. General 

 colour a soft g'reyisli rufous, smooth, scarcely grizzled^ darker 

 along the middle of the back, paler on the sides, tlie general 

 tone not unlike tliat of Mus sylvaticus. Belly-hairs grey 

 basally, pure white terminally, the line of demarcation on the 

 sides not sharply marked. Ears rounded, laid forward they 

 reach just beyond the centre of the eye ; slaty grey in colour, 

 thinly clothed with very sparse fine hairs, so minute that the 

 ear as a whole looks quite naked. Hands and feet whitish, 

 tlie dark colour of tlie body not encroaching on the meta- 

 podials ; pads as usual 5-Q, smooth, rounded, well defined. ; 

 palms and soles quite naked, the skin perfectly smooth 

 between the pads ; pads at bases of first and fifth hind digits 

 each with a small supplementary external pad. Hallux 

 reaching to the base of the second digit, fifth toe to the distal 

 end of the first phalanx of the fourth. Tail longer than head 

 and body, very slender, pale si ate- coloured above, scarcely 

 lighter below, thinly haired, the hairs not hiding the scales; 

 scales very small, the rings numbering about seventeen to the 

 centimetre. Mammae 1 — 2 = 6. 



ShuJL — Upper profile evenly but decidedly convex. Inter- 

 orbital region broad and smooth, its edges sharply square, 

 but without upwardly projecting ridges ; posterior part of 

 frontal embraced laterally by two slender arms of the parietals, 

 which run forwards close to the supraorbital edges. Inter- 

 parietal large, its antero-posterior diameter fully or slightly 

 more than half its transverse diameter. Anterior zygoma- 

 root short, its anterior edge evenly convex forward. Diastema 

 very long, owing to the small size of the molars. Anterior 

 palatine foramina ending just in front of the level of the root 

 of 5^^ Bullaj small, little swollen. 



Teeth. — Incisors orange above, rather paler below. Molars 

 excessively small, their combined length less than half the 

 diastema ; their surfaces too much worn in the type for 

 description, but their structure is apparently similar to that 

 found in the small-toothed African species, such as M. albipes 

 ox M. concha; ^li with the usual antero-internal but noantero- 

 external secondary cusp. 



Dimensions of the type (an adult or even aged female in 

 alcohol) : — 



Head and body 108 millim. ; tail 133 ; hind foot 22 ; heel 

 to front of last foot-pad 10 ; ear, above crown, 13'5. 



Skull : nasal tip to back of interparietal 32*3 ; greatest 

 breadth 15; nasals, length 12*2, breadth 4; interorbital 



