Chap. XII. OCEANIC ISLANDS. 389 



have selected as presenting the greatest amount of 

 difficulty, on the view that all the individuals both of 

 the same and of allied species have descended from a 

 single parent ; and therefore have all proceeded from a 

 common birthplace, notwithstanding that in the course 

 of time they have come to inhabit distant points of the 

 globe. I have already stated that I cannot honestly 

 admit Forbes's view on continental extensions, which, 

 if legitimately followed out, would lead to the belief 

 that within the recent period all existing islands have 

 been nearly or quite joined to some continent. This view 

 would remove many difficulties, but it would not, I 

 think, explain all the facts in regard to insular produc- 

 tions. In the following remarks I shall not confine 

 myself to the mere question of dispersal; but shall 

 consider some other facts, which bear on the truth of 

 the two theories of independent creation and of descent 

 with modification. 



The species of all kinds which inhabit oceanic islands 

 are few in number compared with those on equal con- 

 tinental areas : Alph. de Candolle admits this for plants, 

 and Wollaston for insects. If we look to the large 

 size and varied stations of New Zealand, extending over 

 780 miles of latitude, and compare its flowering plants, 

 only 750 in number, with those on an equal area at 

 the Cape of Good Hope or in Australia, we must, I 

 think, admit that something quite independently of 

 any difference in physical conditions has caused so great 

 a difference in number. Even the uniform county of 

 Cambridge has 847 plants, and the little island of 

 Anglesea 764, but a few ferns and a few introduced 

 plants are included in these numbers, and the com- 

 parison in some other respects is not quite fair. We 

 have evidence that the barren island of Ascension 

 aboriginally possessed under half-a-dozen flowering 



