OF THE AUSTRALIAX MAKSUPIALIA. 



201 



Avitli that genus, because iliere Avas proljubly, in the phalangerine ancestors of both 

 forms, as in the existing Phalangcridsp, several types of dentition, but only one general 

 type of pes. Fotorous has retained a fairly i)riniitive type of pes on account of its more 

 fossorial and less saltatorial habit. 



The connections of the Eettongiinte with the Phalangeridae are doubtful, but the 

 characters of the sectorials afford a slight suggestion of a common origin of three lines 

 ending in the present division, in Burnimijs, and in FhalaiKjer. Iliipsipriimnodoii is 

 closely allied to, if not itself the actual ancestor of Bettongia. The aunectant species is 

 B. 'penicillcda. Bettongia is further the prototype both in dentition and foot-structure 

 of JEpi/pri/mnus. 



3Iacropus 

 (Kangaroos). 



j\liici-opus 

 (Large Wallabies). 



Macro p us 

 (Small Wallabies). 



/S'eio?i?/.i'. 



Dorcopsii. 



JSpyprymnus, 



Diii'lrokii/us. 



Cahjiri/ mints. 



llypsiprymnodon. 



Primitive PlialanKcrina:. 



In the Potoroina', a common stem-form, not far removed from Petaunis or, better, 

 Gi/mnobelidetis, has given rise to Potorons platyops as a short-limbed fossorial form and 

 to Catoprymniis as a free plains living cursorial form. The former a})pears to have 

 spread from West Australia eastward to Tasmania, giving rise to the remaining species. 

 Caloprymnus shows the closest ajiproach of all the Potorointo and Bcttongiinie to the 

 Macropodinae. 



In the brachyodont section of the Macropodinaj we liavc first the genus Bendrolagns, 

 representing an arboreal derivative of some primitive form rather than a specialized one 

 such as Ilacropiis. Lorcopsis represents a secondarily terrestrial deiivative of Bciuho- 

 lagus, which begins to parallel Macropus. The sequence of modifications of the sectorial 

 premolars and the retention of certain primitive characters in the general dentition 

 preclude the possibility of a derivation of Bendrolagus from Macropus tlirough 



