PHASCOLOTHERIUM. 67 



and the Myrmecolius, and resembles the Opossum and 

 Thylacine, having three false and four true molars, or 

 seven grinders altogether, in each maxillary ramus. The 

 distinction between the false and true molars is however 

 much less strongly marked, both in the Phascolothere 

 and Thylacine, than in the Opossum. The difference be- 

 tween the false and true molars in the Opossum is chiefly 

 indicated by the addition, in the true molars, of a pointed 

 tubercle on the inner side of the middle large tubercle, and 

 in the same transverse line with it ; but in the Phascolo- 

 there, as in the Thylacine, there is no corresponding tuber- 

 cle on the inner side of the large, middle, pointed cusp ; 

 its place is occupied in the Phascolotherium by a ridge, 

 which extends along the inner side of the base of the crown 

 of the true molars, and, projecting a little beyond both the 

 anterior and posterior smaller cusps, gives the quinquecus- 

 pid appearance to the crown of the tooth, as represented 

 by Dr. Buckland in his magnified view of the antepenulti- 

 mate grinder of the Phascolotherium, given in the 2nd 

 Plate of the illustrations of the Bridgewater Treatise. In 

 the Thylacine the internal ridge is not continued across the 

 base of the large middle cusp, but it extends along and 

 beyond each of the lateral cusps, so as to give the tooth a 

 similar quinquecuspid form to that which characterizes the 

 true molars of the Phascolothere. Connecting the close 

 resemblance which the molar teeth of the Phascolothere 

 bear to those of the Thylacine with the similarities which 

 have been already shown to exist in the several character- 

 istic features of the ascending ramus of the jaw, I am of 

 opinion that the marsupial extinct genus, indicated by the 

 Stonesfield fossil here described, was nearly allied to 

 Tkyladnus, and that its position in the marsupial series is 

 between Thylacinus and Didelphys. 



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