HuTTON. — On the Geographical Relations of the N.Z. Fauna. 233 



species living on so small an island is very remarkable when contrasted with 

 other parts of the world. The continent of Africa, including Arabia, contains 

 but one, or according to some naturalists two, species of ostrich. South 

 America, from Patagonia to Peru, has but three sj^ecies of rhea, each inhabit- 

 ing a separate district. Australia possesses two species of emu, one on the 

 eastern and the other on the western side, and one species of cassowary 

 on the northern, while five other species of cassowary inhabit other detached 

 islands, from New Britain and New Guinea to the Molucca Islands. I 

 believe that outside of New Zealand no two species of Struthious bird are 

 found living in the same district, while here we have now four species of kiwi 

 and not long ago had at least half-a-dozen species of moa as well. How can 

 this be accounted for % The solution is readily found by examining the 

 distribution of the cassowaries. Here we have six species inhabiting six 

 isolated localities. If now this region of the earth were to be elevated these 

 six species might mingle, and if it were subsequently to sink again, all six 

 species would undoubtedly be driven to the higher lands, and we should have 

 in this supposed island a representation of New Zealand inhabited by six 

 species of Struthious bird. 



In order, therefore, to account for the numerous species of Dinornis we 

 must suppose an ancient continent, inhabited by one or two species, to sink, 

 and the birds to take refuge on the different mountain ranges left as islands 

 above the water. We must suppose that they remained thus isolated from 

 one another for a sufficiently long period to allow of specific changes being 

 brought about ; that then, by an elevation of the land they once more mingled 

 together, and that, on subsidence again taking place. New Zealand as the 

 central mountain chain formed a harbour of refuge for them all. 



Whether this isolation of species points to some cause as yet unrecognized, 

 by which in the struggle for life no two species of Struthious bird can live in 

 close proximity I will not venture to give an opinion, but it is a fair subject 

 for inquiry, and one on which the careful study of the relative ages of moa 

 bones might throw considerable light, and enable us perhaps to understand the 

 great mortality that must have taken place amongst the moas when confined 

 to these small islands long before man set his foot here. 



The distribution, therefore, of the Struthious birds in the Southern 

 Hemisphere points to a lai'ge Antarctic Continent stretching from Australia 

 through New Zealand to South America, and perhaps on to South Africa. 

 This continent must have sunk, and Australia, New Zealand, South America 

 and South Africa must have remained isolated from one another long enough 

 to allow of the great differences observable between the birds of each country 

 being brought about. Subsequently New Zealand must have formed part of 

 a smaller continent, not connected either with Australia or South America, 



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