condition of dentition, the functional teeth being reduced to one 

 pair of large cutting incisors situated close to the median line, and 

 one great, trenchant, compressed premolar, on each side above and 



below. It was first 

 described as a car- 

 nivorous Marsupial, 

 and named, in ac- 

 cordance with its 

 presumed habits, 

 " as one of the fel- 

 lest and most de- 

 structive of preda- 

 tory beasts " ; but, 

 as its affinities are 

 certainly with the 

 Phalangeridce and 

 Macropodidce, and 

 its dentition com- 

 pletely unlike that 

 of any known pre- 

 daceous animal, this 

 view has been called 

 in question. 



The dentition is 

 nearer to that of the 



PIG. 51. Front view of skull of Thylacoleo carnifex, restored. 

 J natural size. From Quart. Journ. Geol. Soc. vol. xxiv. p. 312. 



existing Phalangeridce than to that of the Macropodidce, and the 

 genus may be provisionally regarded as the type of a distinct 

 subfamily of 'the former. 



Family MACROPODID^E. 



Dentition i -, c ^ ~~ , p ~, m - Incisors sharp and cutting, 



those of the lower jaw frequently having a scissor -like action 

 against one another ; upper canine, if present, small. Penultimate 

 premolar shed with the fourth milk-molar, which is molariform and 

 long persistent. Molars wide, and either transversely ridged or 

 bluntly tuberculate. Premolars and molars moving forwards in the 

 skull as the age of the animal increases, this being most marked in 

 the larger species. Masseteric fossa of mandible hollowed out 

 below into a deep cavity walled in externally by a plate of bone, 

 and communicating with the inferior dental canal by a large 

 foramen. Hind limbs usually larger than the anterior ones, and 

 progression generally saltatorial. Fore feet with five digits ; hind 

 feet syndactylous, the fourth digit being very large and strongly 

 clawed ; hallux usually absent. Tail generally long and hairy, 



