GENERAL INTRODUCTION 31 



Mr. G. M. Thomson, and Mr. W. Botting Hemsley. It 

 is impossible to deal fully with the results of their work, but 

 an attempt will be made to give an intelligible, though 

 necessarily brief account of it. 



Of the 1,400 flowering plants which New Zealand contains, 

 some two-thirds are found nowhere else. A considerable pro- 

 portion of the remainder is confined to New Zealand and 

 Australia, or to New Zealand, Australia, and other southern 

 districts. A section of the New Zealand flora shows a most 

 striking South American afdnity. There are a few cosmopolitan 

 plants, and there is also an element usually termed Scandinavian, 

 which shows a relationship to a certain portion of the flora of 

 the Northern Hemisphere. As, however, the endemic species 

 constitute by far the greater portion of the flora, the foreign 

 affinities are best shown in the genera. Of these, 80 per cent, 

 are found in New Zealand, 10 per cent are endemic, and the 

 remaining 10 per cent are variously distributed. It is clear, 

 therefore, that the basis of the New Zealand flora has either 

 been derived from Australia, or that the element common to 

 both has come from the same source. As a matter of fact, the 

 latter hypothesis is best supported by the evidence. 

 Several lines of argument, as has already been stated, show 

 that at one time New Zealand was more extensive than it is 

 now. It then stretched to the northward, through Lord Howe 

 and Norfolk Island, to New Caledonia, and perhaps even 

 as far as the Solomons. Another continental arm connected 

 Queensland with New Caledonia. Through these northern 

 extensions there passed, though not necessarily at the 

 same time, southward to New Zealand, and westward 

 to Queensland, the ancestral forms of much of the 

 vegetation common to the two countries. In this migra- 

 tion we have an explanation of the sub - tropical fades 

 of the New Zealand forests, and also of the fact that nearly 

 ninety per cent of our forest flora has Melanesian affinities. 

 It is probable that this northern extension existed in Miocene 



