THE GREATER KANGAROO. 277 



munication between the northern shores of Australia and the 

 continent of India, these animals possess no organic type among 

 the mammals of the Old World ; and those, on the other hand, 

 have but few representatives within the boundaries of New 

 Holland and its dependencies. The little which we know of 

 its geology warrants us in concluding that Australia, like other 

 parts of our globe, has had its changes and revolutions -, the 

 osseous caves and breccia of Wellington Valley, contain frag- 

 ments of the bones of mammals in great abundance and 

 perfection ; and these remains, sufficiently important in other 

 respects, acquaint us with the singular and interesting fact, 

 that, even at that early period, before the operation of those 

 causes which swept them off from the surface of the earth, the 

 mammals of Australia were, generally speaking, of the marsupial 

 order, of which, I believe, only a single undoubted species has 

 been hitherto discovered among fossil remains in the Old 

 World. 



" Another remarkable circumstance, connected with this 

 singular tribe of animals, is the very limited number of species 

 which have been hitherto discovered, considering the vast extent 

 of the continent over which they are dispersed, and the con- 

 sequent variety of soil and climate to which they are exposed. 

 The genera to which they belong are also comparatively few 

 in number ; all the marsupials hitherto discovered upon the 

 continent of Australia and its neighbouring isles, present only 

 eleven really distinct and well denned types of organic structure, 

 or genera ; being on an average not quite one genus to every 

 three known species. This extreme paucity both in the number 

 and variety of its mammals, supposing it to be really the case, 

 becomes the more surprising when we consider that the con- 

 tinent of Australia alone, without reckoning the large islands 

 of New Guinea, New Zealand, and Van Dieman's Land, and 

 the numerous smaller groups, its natural dependencies, embraces 

 an extent of nearly thirty degrees of latitude by forty degrees 

 of longitude, and ranges throughout an almost infinite variety 

 of climate, from the parched and barren sands which border 



