CHAP. XXI NEW ZEALAND 485 



the Bampton shoal west of New Caledonia, and Lord 

 Howe's Island further south, formed the western limits 

 of that extensive land in which the great wingless birds 

 and other isolated members of the New Zealand fauna 

 were developed. Whether this early land extended east- 

 ward to the Chatham Islands and southward to the 

 Macquaries we have no means of ascertaining, but as the 

 intervening sea appears to be not more than about 1,500 

 fathoms deep it is quite possible that such an amount of 

 subsidence may have occurred. It is possible, too, that 

 there may have been an extension northward to the 

 Kermadec Islands, and even further to the Tonga and 

 Fiji Islands, though this is hardly probable, or we should 

 find more community between their productions and those 

 of New Zealand. 



A southern extension towards the Antarctic continent 

 at a somewhat later period seems more probable, as 

 affording an easy passage for the numerous species of 

 South American and Antarctic plants, and also for the 

 identical and closely allied fresh-water fishes of these 

 countries. 



The subsequent breaking up of this extensive land 

 into a number of separate islands in which the distinct 

 species of moa and kiwi were developed — their union 

 at a later period, and the final submergence of all but 

 the existing islands, is a pure hypothesis, which seems 

 necessary to explain the occurrence of so many species 

 of these birds in a small area but of which we have no 

 independent proof. There are, however, some other facts 

 which would be explained by it, as the presence of three 

 peculiar but allied genera of starlings, the three species of 

 parrots of the genus Nestor, and the six distinct rails of 

 the genus Ocydromus, as well as the numerous species in 

 some of the peculiar New Zealand genera of plants, which 

 seem less likely to have been developed in a single area 

 than when isolated, and thus preserved from the counter- 

 acting influence of intercrossing. 



In the present state of our knowledge these seem all 

 the conclusions we can arrive at from a study of the New 

 Zealand fauna ; but as we fortunately possess a tolerably 



K K 



