INTRODUCTION. x 



therium should have migrated from opposite extremes, 

 and have met in the temperate latitudes of North Ame- 

 rica, where, however, their remains are much more scanty 

 than in their own proper provinces. 



Australia in like manner, yields evidence of an analogous 

 correspondence between its last extinct and its present 

 aboriginal Mammalian Fauna, which is the more inte- 

 resting on account of the very peculiar organization of 

 most of the native quadrupeds of that division of the 

 globe. That the Marsupialia form one great natural 

 group, is now generally admitted by zoologists ; the re- 

 presentatives in that group of many of the orders of 

 the more extensive placental sub-class of the Mam- 

 malia of the larger continents have .also been recog- 

 nised in the existing genera and species : the Dasyures, 

 for example, play the parts of the Carnivora, the Bandi- 

 coots of the Insectivora, the Phalangers of the Quadru- 

 mana, the Wombat of the Rodentia, and the Kangaroos, 

 in a remoter degree, that of the Ruminantia. The first 

 collection of Mammalian Fossils from the ossiferous caves 

 of Australia brought to light the former existence on that 

 continent of larger species of the same peculiar marsu- 

 pial genera : some, as the Tliylacine, and the Dasyurine 

 sub-genus represented by the Das. ursinus, are now ex- 

 tinct on the Australian continent, but one species of each 

 still exists on the adjacent island of Tasmania; the rest 

 were extinct Wombats, Phalangers, Potoroos and Kanga- 

 roos, some of the latter being of gigantic stature. Sub- 

 sequently, and after a brief interval, we obtain a know- 

 ledge of the former existence in Australia of a type of 

 the marsupial group, exemplified by the genera Diprotodon 

 and Nototheriuni* which represented the Pachyderms of 



* See " Catalogue of Fossils in the Museum of the College of Surgeons," 4to., 

 1845, pp. 291, 336, pis. vi, x. 



