296 



ORDERS OF MAMMALIA. 



chisel-shaped. The incisors differ from those of the Kan- 

 garoos, and agree with those of the Wombats, in growing 

 from persistent pulps ; there are no canines ; there is a single 



Fig. GOS.— Skull of Diprotodon Anstralis. (After Owen.) Post-Tertiary, Australia. 



small premolar, which is lost in aged animals ; and there 

 are four grinding molars on each side of each jaw. The 

 dental formula is — 



0—0 



1 — 1 



1—1 



0- 



; 2ym 



-0 1—1 



m 



4—4 

 4—4 



28. 



The fore-limbs appear to have been about equal in size to 

 the hind-limbs, and the mode of progression must have been 

 quite unlike that which obtains in the Kangaroos. In size, 

 also, Dqyrotodon must have many times exceeded the largest 

 of the living Kangaroos, since the skull measures three feet 

 in length. 



Notothcriuni ( = Zygomaturus) resembles Diprotodon in some 

 respects ; but the lower incisors are diminutive, and all the 

 front teeth are rooted. 



Lastly, there is a group of Diprotodonts in which we have 

 only the singular extinct genus Thylacoleo (fig. 609), in 

 which the most prominent feature of the dentition is tlie 



