CH. IV] CASSOWARIES AND MOAS. 211 



part of Captain Hutton as explanatory of the Moas of 

 New Zealand. These recently vanished birds are re- 

 presented by a large number of different species which 

 are now placed in more than one genus. The area upon 

 which they lived is small, and accordingly the number of 

 species is rather remarkable. In the Australian region 

 there are nearly as many Cassowaries as there are Moas. 

 Now these Cassowaries are spread over a considerable 

 number of islands; they are not limited to the con- 

 tinent of Australia but occur also in Ceram, New 

 Britain, New Ireland, &c. On these various islands and 

 continent are different species. This suggests that 

 isolation and the absence of opportunity for retaining the 

 type by crossing with the parent stock was responsible 

 for the great variety of Cassowaries. If New Zealand 

 had been at one time a mass of not very distantly 

 separated islands, each inhabited by its own particular 

 species of Moa, a state of affairs very like that now 

 existing among the islands lying to the north of Australia 

 would result ; this is precisely what Mr Hutton in effect 

 suggests. Mr Wallace regards the suggestion as a rea- 

 sonable one, and it is impossible to follow a better opinion. 

 If there has been this oscillation of New Zealand, whereby 

 a continent (comparatively speaking) has been broken up 

 into an archipelago, and reconstructed into a continent 

 again, it may be that we have a clue to the existence of 

 the large, clumsy, and flightless birds such as the 

 Cnemiornis and the Notornis. Their case might well be 

 analogous to that of the Galapagan and Aldabran tort- 

 oises ; or perhaps also to that of the flightless beetles of 



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