CHAPTER XVII 



HISTORY OF THE MARSUPIALIA 



The marsupials are a group of more primitive structtire 

 and greater antiquity than any which we have yet considered, 

 so primitive, indeed, that they are referred to a separate 

 infraclass, the Didelphia or Metatheria. The order is one of 

 very great variety in size, form, appearance, diet and habits, 

 and mimics several of the higher orders in quite remarkable 

 fashion. Herbivorous, insectivorous and carnivorous forms 

 are all numerous, as well as arboreal, terrestrial, cursorial, 

 leaping and burrowing genera. Some are like hoofed mammals 

 in appearance and the Rodentia, Caj-nivora and Insectivora 

 are also closely imitated in externals. With all this diversity, 

 most luiusual within the limits of a single order, there is such 

 a unity of structure, that a division of the group into two or 

 more orders is impracticable. 



At the present time, marsupials are very largely confined 

 to AustraUa and adjoining islands, where they constitute nearly 

 the whole mammahan fauna, and it is in the Australian region 

 that the remarkable diversity already mentioned is to be ob- 

 served. There are found the phalangers, kangaroos, bandi- 

 coots, Tasmanian "devil" and "wolf," and banded anteaters, 

 not to mention many other curious creatures. In the western 

 hemisphere only the opossums {Didelphis, Chironectes) and 

 one very interesting relic of a long vanished assemblage, 

 Ccenolestes of Ecuador and Colombia, are in existence to-day. 

 The opossums, of which some twenty-three species are recog- 

 nized, have their headquarters in South America, to which 



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