432 





PALAEONTOLOGY. 



development of the tympanic bulla in the alisphenoid, by the 

 very small relative size of the brain, and by other characters 

 detailed in the " Philosophical Transactions "* for 1859. The 

 carnassial tooth (p) is 2 inches 3 lines in longitudinal extent, 

 or nearly double the size of that in the lion. The upper 

 tubercular tooth (in, i) resembles in its smallness and position 

 that in the placental Felines. But in the lower jaw the car- 



Fig. 173. 



Skull of a large extinct Marsupial Carnivore ( Thylacoleo carnifex), 



Pleistocene, Australia. 



nassial (p) is succeeded by two very small tubercular teeth 

 (ra i and 2), as in Plagiaulax (fig. 93, p. 332) ; and there is a 

 socket close to the symphysis of the lower jaw of Thylacoleo 

 which indicates that the canine may have terminated the 



* " On the Fossil Mammals of Australia. Part I. Description of the 

 Thylacoleo carnifex" By Prof. Owen, etc. 



