INTRODUCTION Ivii 



affinities of species to species, and genus to genus, in the groups of allied forms, has led 

 me to believe in the extreme rarity of a successful immigration from outside. The 

 extraordinary gaps in the fauna of whole families of wide distribution and containing 

 countless species, many of which no doubt would, and some of which, after introduction 

 by man, are known to thrive in the islands, show clearly how hardly and rarely have 

 immigrants reached them from without. A limited number of birds and insects, species 

 of well-known migratory habits, for which no seas are impassable, doubtless, arrive 

 continually, but these, only in the event of such migration ceasing, are likely to produce 

 new and endemic forms. 



The phenomena exhibited by the Flora, appear to me to be extremely similar to 

 those of the Fauna. There may be seen the same notable absences of forms widely 

 distributed elsewhere, the same multiplication of allied species of many of the genera 

 that are present, the same groups of allied genera embracing many species. I believe 

 that the explanation of these facts is quite in accordance with that which I think to be 

 true of the Fauna, as above stated. Dr H. B. Guppy, who has paid much attention to 

 the flora of the Pacific islands and the dispersal of plants, as I understand his book, 

 takes a different view of these allied genera and species, and would consider them the 

 result of numerous immigrants. 



He considers that there existed an ancient age of Conifers in the Pacific, thereby 

 accounting for the three genera Dammara, Dacrydiuvi and Podocarpus in the Western 

 islands. These three genera are entirely absent from Tahiti and the neighbouring 

 islands, and from the Hawaiian group, the explanation being that at the time these 

 conifers reached the islands of the Western Pacific, the Hawaiian and Society groups 

 did not exist. Later, he tells us, there was an age of Compositae and arborescent 

 Lobeliaceae, during which nine endemic genera of the former reached the Hawaiian 

 group, and one other (Fitchia) became established in Tahiti. There is no trace of this 

 era of Compositae in the Western groups (Fiji, Samoa) owing to the submergence of 

 the Western islands during Tertiary times, the supposition being that during the time, 

 when Hawaii and Tahiti were receiving their Compositae from America, the Western 

 islands existed above water at most as small islets formed by their highest mountain 

 peaks. 



Two of the coniferous plants are said to possess seeds that could be carried across 

 wide oceans by the aid of birds, even to the Hawaiian group, and yet during the whole 

 period between the time when the Hawaiian group and Tahiti came into existence, and 

 the present, it does not appear that these have even reached the Samoan group, so 

 comparatively near to Fiji. One would rather suppose that the presence of the conifers 

 in Fiji, like its Cicindelid beetles and some other animals, is due to the continental 

 character of the group. 



As to the era of Compositae in the Pacific, the presence of these in the Hawaiian 

 islands and their absence from the western groups does not seem to require the geological 

 F. H. I. h 



