158 MARSUPIALIA 
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 
Phalangeride and 
Macropodide, and 
its dentition com- 
pletely unlike that 
of any known pre- 
daceous animal, this 
view has been called 
——— in question. 
Fig. 51.—Front view of skull of Thylacoleo carnifee, restored. The dentition is 
3 natural size. From Quart. Journ. Geol. Soc. vol. xxiv. p. 312. nearer to that of the 
existing Phalangeride than to that of the Mfucropodide, and the 
genus may be provisionally regarded as the type of a distinct 
subfamily of the former. 
Family MAcRopopID&. 
ae 3 0—1 2 4 F 
Dentition 2 > ¢ ( 7 3 Prmy 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, antl 
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, 
