478 ISLAND LIFE 



How far back in geological time these creatures or their 

 ancestral types lived in New Zealand we have as yet no 

 evidence to shoAv. Some specimens have been found under 

 a considerable depth of fluviatile deposits which may be of 

 Quaternary or even of Pliocene age ; but this evidently 

 affords us no approximation to the time required for the 

 origin and development of such highly peculiar insular 

 forms. 



Past Changes of New Zealand deduced from its Wingless 

 Birds. — It has been well observed by Captain Hutton, in 

 his interesting paper already referred to, that the occurrence 

 of such a number of species of Struthious birds living to- 

 gether in so small a country as New Zealand is altogether 

 unparalleled elsewhere on the globe. This is even more 

 remarkable when we consider that the species are not 

 equally divided between the two islands, for remains of no 

 less than ten out of the eleven known species of Dinornis 

 have been found in a single swamp in the South Island, 

 where also three of the species of Apteryx occur. The 

 New Zealand Struthiones, in fact, very nearly equal in 

 number those of all the rest of the world, and nowhere else 

 do more than three species occur in any one continent or 

 island, while no more than two ever occur in the same dis- 

 trict. Thus, there appear to be two closely allied species 

 of ostriches inhabiting Africa and South-western Asia re- 

 spectively. South America has three species of Rhea, each 

 in a separate district. Australia has an eastern and a 

 western variety of emu, and a cassowary in the north ; while 

 eight other cassowaries are known from the islands north 

 of Australia — one from Coram, two from the Aru Islands, 

 one from Jobie, one from New Britain, and three from New 

 Guinea — but of these last one is confined to the northern 

 and another to the southern part of the island. 



This law, of the distribution of allied species in separate 

 areas — which is found to apply more or less accurately to 

 all classes of animals — is so entirel}^ opposed to the crowding 

 together of no less that fifteen species of wingless birds in 

 the small area of New Zealand, that the idea is at once 

 suggested of great geographical changes. Captain Hutton 

 points out that if the islands from Ceram to New Britain 



