Mr. 0. Thomas on new Tasmanian Muridw. 415 



Mus iieluttnuSj sp. n. 



Fur excessively long, soft, and velvety, almost like that of 

 a Chinchilla in texture. General colour above a peculiar 

 yellowish olivaceous gvey, the hairs, which are nearly 1 inch 

 long, being dark slaty grey for nine tenths of their length, 

 with their extreme tips yellow. There are also many longer 

 black hairs intermixed with the others. Belly bluish grey, 

 the bases of the hairs light slate-colour and the tips dirty 

 white. Ears, feet, and tail uniformly dark brown. 



Skull rather light and slender, with well-marked supra- 

 orbital ridges. Front edge of the anterior zygoma-root slanting 

 in all three specimens, thus differing from all other Australian 

 rats, in which it either projects forward above or is strongly 

 concave below (see woodcut, fig. 4). 



Of this species two skins and a skeleton were presented to 

 the Museum in 1877 by Mr. A. Simson. 



Dimensions. 



Mastaeomys ficscus, 

 2 in alcoliol. 



in. 



Head and body 5 -GO 



Tail 3-70 



Hind foot 1-22 



Forearm and hand 1'55 



Ear-couch, length 'OS 



Muzzle to ear 1*30 



Skulls. 



Mastaeomys fuscus, Mus velutinus. 



type. Skull of ft. Oftheskeletou. 



Greatest length 1-42 1-34 1-30 



Breadth across zygomata . . -84 -71 -OS 



Length of lower jaw .... -98 -SB -80 



Nasal bones -51 -52 -46 



Breadth between orbits . . -17 -20 -21 



Anterior palatine foramina. "30 '25 '25 



Incisors to first upper molars "35 -37 -36 



Upper molar series "39 -30 -29 



Besides these two species, the British Museum possesses 

 specimens of two other rats from Tasmania, namely Mus fus- 

 cijjesy Waterh., and a species closely allied to, if not identical 

 with, Mus lineolatus, Gould. All four are long-haired rats of 

 about the same size and proportions, with very similarly 

 coloured fur ; but they are all readily distinguishable by the 



29* 



