920 ROBERT COLLETT, 



equally as distant from the nearest premolar. pi is also isolated (in 

 the feraale p^ is almost touching p^ on the one side). There is 

 otherwise nothing abnormal in the dentition. 



In the Upper jaw, the central incisor is considerably broader and 

 longer than the others, which are very small, and equal in size. 



The canines are small, in size about equal to * s . 



Of the premolars, ^i is also small, almost the smallest of the 

 teeth, inconsiderably smaller than the canines; thus the 2 posterior 

 incisors, the canine, and the 1*' premolar are all about equal in size, 

 and likewise small. ^2 is somewhat larger, has one large and one 

 indistinct cusp ; p^ is the largest. 



The molars are normal. 



In the lower jaw the canines in both specimens are quite rudi- 

 mentary ; in the mature female it is only present on one side, and is 

 here only visible under the lens; it has been entirely hidden in the 

 jaw in the living individual. In the young male its socket is still to 

 be Seen, but the teeth themselves have fallen out, 



Of the premolars , a rudimentary p 1 is present on one side in 

 both specimens ; and this also is not functional. p^ is in use , nar- 

 rower than the upper one, which is also the case with the molars. 



This species is easily distinguishable from Ps. caudivolvulus, not 

 only by its quite diflferent colouring, but also by its extremely short ears, 

 which are almost completely hidden in the für, whilst in the other 

 species they are large and prominent; their greatest breadth in Ps. 

 herbertensis is about 13 mm , while the breadth on an equally large 

 specimen of Ps. caudivolvulus (from S. Australia) is 26 mm. The 

 naked rhinarium is besides greater, and the hair covering of the tail 

 slightly wavy and prominent. The difference in the structure of the 

 Skulls is in several respects conspicuous, especially in the construction 

 of the nasalia, of the palate, of the bullae osseae, and of the inter- 

 maxillaria. 



43. JPseudochirus caudivolvulus (Kerr) 1792. 



Didelphis caudivolvula Kerr., Anim. Kingd. vol. I, p. 196 (1792). 

 Pseudochiriis caudivolvulus Jent. , in : Notes Leyden Mus. vol. VII, p. 2 1 



(1885). 



A, Coomooboolaroo, Febr. 1884 (skin with skull). 



It is not without interest, that this specimen originated from a 

 locality lying comparatively near the spot, from which Cook, in 1770, 



