264 



MAMMALIA. 



each with a single root. Then follows an enormous sectorial premolar 

 with two roots, but no heel. Finally, a very small ovoid tubercular molar, 

 with two roots, is closely pressed to the postero-internal angle of the 

 sectorial. The mandible has a relatively large coronoid process, and a 

 conspicuous inflection of the lower margin near the angle. The articular 

 condyle is transversely extended, and placed on the same level as the 

 dentition or even below it. There is a single pair of enlarged incisors at 

 the symphysis, pointed and laterally compressed. Next are two diminutive 



FIG. 155. 



Thylacoleo carnifex; right lateral aspect of skull and mandible, about one- 

 third nat. size. Pleistocene ; Queensland, c, canine ; i, incisors ; m, 

 molars ; pm., premolars. 



premolars, immediately followed by the great sectorial premolar, which 

 has two roots, the hinder the largest. The small first molar has two 

 roots, while the second molar is a mere tubercular rudiment with one 

 root, sometimes even absent. Limb-bones from the Wellington Caves, 

 New South Wales, referred with much probability of correctness to 

 Thylacoleo, denote a very nimble animal, and the innominate bone ex- 

 hibits a striking resemblance to that of Thyladnus. The typical species 

 is Thylacoleo carnifex, with skull about 0'26 m. in length, and probably all 

 the known remains are Pleistocene or of later date. 



A family of gigantic extinct herbivorous Diprotodonts, not 

 yet completely known, but apparently related both to the 

 phalangers and the kangaroos, is that of the Diprotodontidae, 

 with the type genus Diprotodon. Nototherium is a smaller 

 animal, either of this or a closely allied family. 



