MONOTREMATA AND MARSUPIALIA. 



295 



. 1—1 0—0 1—1 4—4 



I ; c ; ijm ; m = 24 



1—1 0—0 1—1 4-4 



A second great group of the Diprotodont Marsupials is 

 represented at the present day by the existing Kangaroos 

 {Macropus) and Kangaroo - rats {Hypsiprymnus). In this 

 group the hind-legs are longer than the fore-legs ; the lower 

 incisors are nearly horizontal, and are rooted (fig. 599, A, and 

 fig. 607) ; and there are no canines. 



Fig. (507.— Skull of the living Macropus Bennetti. (After Giebel.) 



The dental formula of the Kano-aroos is- 



. o- 

 ^ — 



1- 



0-0 1- 



; p7n — 



0—0 1- 



4—4 



m ^28 



4—4 



The living genus Macwpus is represented in the Post- 

 Tertiary deposits of Australia by species in all essential 

 respects agreeing with the recent forms but of gigantic size, 

 one species being as large as the Ehinoceros. The Stlicnums 

 and Protenmodon of the same deposits are related^ on the 

 other hand, to the Tree-kangaroos {Dendrolagus) of New 

 Guinea. Associated with these extinct types of Kangaroos, 

 we have also representatives of the smaller Kangaroo-rats 

 (^Hypsiprymnus and Bettongia). 



A third group of Diprotodonts is represented in the Post- 

 Tertiary of Australia by the extraordinary extinct types 

 Biprotodon and Nototherium, which were vegetable-feeders, 

 like the living Kangaroos, but present certain peculiarities of 

 their own. In Biprotodon (fig. 608) the two lower incisors 

 are round and tusk-like, and there are six upper incisors, of 

 which the two median ones are of large size, curved, and 



