398 Mr. 0. Thomas on a second 



crown slaty grey at tlieir bases, those of the muzzle, chin, 

 chest, belly, limbs, and tail pure white or yellowish white to 

 their roots. Naked rhinarium small, not running back along 

 the top of the muzzle, as in P. lagotts. Ears, as usual, enor- 

 mously long, laid forward they reach beyond the muzzle ; 

 evenly thinly clothed with very fine short silvery hairs, which 

 form a delicate fringe round their edges ; their substance 

 yellowish flesh-colour, except for their posterior half ter- 

 minally, where it is slaty grey. Fore limbs pure white, 

 thickly hairy everywhere, except along the underside of the 

 fingers ; thumb and fifth finger clawlcss, as usual ; second and 

 third fingers subequal, fourth reaching to the middle of the 

 terminal phalanx of the third, fifth reaching just beyond, and 

 thumb just to the level of, the base of the fourth ; a small 

 round naked pad at the base of each of the digits except the 

 thumb, much more distinctly defined than in P. lagotis. 

 Hind limbs also pure white, without any black hairs along 

 the sole ; the latter completely hairy, except on the compound 

 terminal projection, on which there are two small but distinct 

 pads ; fifth toe reaching to the end of the first phalanx of the 

 fourth ; united second and third to the base of the fourth. 

 Tail thin and slender, loholly ichite-haired, the hairs quite 

 short on the sides and below, but above forming a beautiful 

 prominent white crest, increasing in length to the tip, where 

 the hairs are more than 30 millim. in length. 



Skull, so far as can be judged from so young a specimen, 

 with all the essential characters of that of P. lagotis^ except 

 that the bulla3 are more evenly hemispherical in their shape 

 and not so prominently bulbous postero- externally. 



Teeth very much smaller than those of P. lagotis (see 

 dimensions), and showing that P. leucura, when full-grown, 

 cannot be more than two thirds the size of P. lagotis. Upper 

 incisors quite similar in shape to those of that animal ; canines 

 much straighter and slenderer, their antero-posterior diameter 

 at 3 millim. from their tip only 1"6 millim. as compared to 2*3 

 in an immature specimen of P. lagotis with unworn teeth. 

 Pm.^ and pm.^ * shaped as in P. lagotis ; milk premolar 

 (m. pm.^) much smaller than in that species, its transverse 

 diameter equal to, instead of only about half, its longitudinal 

 diameter. Molars differing strikingly from those of P. lagotis^ 

 and showing a distinct approximation to those of Perameles 



* It lias been shown elsewhere that the two anterior premolars of the 

 DaRymid^e, and therefore probably of the other Polyprotodout Marsu- 

 pials, are homologous with the first and third of the placental premolars, 

 and should therefore be called pm.^ and pm.^ (Proc. Roy. Soc. 1887). 



