66 MARSUPIALIA. 



but, in the gentle curve by which the lower margin of the 

 jaw is continued along the line of the symphysis to the 

 anterior extremity of the jaw, the Phascolotherium re- 

 sembles Didelphys more than Dasyurus or Thylacinus. 



It is interesting to find that this analogy is associated 

 with a correspondence in the condition of the teeth at the 

 anterior part of the jaw. In examining the fossil we can 

 scarcely refuse our assent to Mr. Broderip's opinion, that 

 there were originally four incisors in each ramus of the jaw 

 of Phascolotherium., as in Didelphys. Of the three incisors 

 which are actually present in the fossil, only the internal 

 and posterior surfaces are displayed, and not the whole 

 breadth of the tooth ; so that in the enlarged figure of the 

 jaw detached from its matrix, the incisors appear both nar- 

 rower and further apart than they really are. The incisors 

 in the Thylacinus are of a prismatic form ; and the surface, 

 corresponding to that which is exposed on the fossil, forms 

 one of the angles, from which the tooth increases in breadth 

 to its anterior part, which forms one of the three facets. 



Allowing for this circumstance, which must be borne in 

 mind in an endeavour to arrive at the true affinities of the 

 Phascolothere, the incisors in that fossil are evidently 

 separated by wider intervals than in Thylacinus, Dasyurus, 

 or Didelphys ; and the Phascolothere resembles, in this 

 respect, as in the smaller proportions of its canine, the 

 genus Myrmecobius. 



In the proportions of the grinders to each other, espe- 

 cially the small size of the hindmost molar, the Phascolo- 

 there resembles the Myrmecolius more than it does the 

 Opossum, the Dasyure, or the Thylacine ; but in the form 

 of the crown it resembles the Thylacine more closely than 

 any other genus of Marsupials. In the number of molar 

 teeth the Phascolothere differs both from the Amphithere 



