Distribution of Fauna and Flora. 301 



One hundred and eleven species of Dicotyledonous plants an^ 

 recorded, and of these ten only are referred to as new, but 

 a considerable number, while not epecifically distinct, differ 

 markedly from specimens from other localities, and may be 

 regarded as local varieties. In fact, as has been pointed out on 

 the authority of Professor Oliver, we are probably here dealing 

 with species in the making [6, 10]. Most of the other plants 

 either occur in the Indo-Malayan islands or are widely distributed 

 tropical forms. 



Of the Monocotyledons seven out of eighteen species are endemic, 

 the remainder being either Indo-Malayan or widely distributed. 



The single Gymnosperm, Cycas circinalis, is found both in the 

 Indo- and Austro-Malayan islands. The ferns are either Indo- 

 Malayan or common tropical forms : only two are described as 

 endemic. The remaining Cryptogams are all, with the exception 

 of one peculiar species of fungus, either Indo-Malayan or widely 

 distributed species. 



The causes which have been instrumental in the introduction 

 of the fauna and flora have been, as usual, the winds and ocean 

 currents, the work of the former being much the more important. 

 The prevailing wind is the south-east trade, which blows on an 

 average 300 days in the year. The nearest land in the direction 

 from which it comes is the north-west coast of Australia, about 900 

 miles away, so that, as might be supposed, the number of species 

 possibly introduced by this means is very small ; perhaps one or 

 two of the butterflies may have reached the island in this way. In 

 fact, as AVallace ^ long ago pointed out in the case of the Azores, the 

 introduction of plants and animals into remote islands is due not 

 so much to ordinary or normal as to extraordinary or exceptional 

 causes. These latter, in the case of Christmas Island, are the 

 storms which, during the rainy season, blow occasionally from the 

 northern quarter, and it is after these, or sometimes even after 

 a few days' steady breeze from this direction, that birds of passage, 

 dragon-flies, various moths and butterflies, and other insects 

 reach the island. It is no doubt, therefore, to these occasional 

 northern winds and storms, that by far the greater number of the 

 species of plants and animals owe their introduction, and, indeed, 

 considering that new arrivals were observed after nearly every gale, 

 it seems rather remarkable that a greater number of forms have 

 not gained a permanent footing. In the case of the birds most 

 of the newcomers were migrants coming south to avoid the 

 northern winter, and would not, in any case, be likely to remain 

 permanently ; the rails, of which at least two species were seen, 

 would probably find it impossible to breed in the island on account 

 of the rats. Several of the species recorded were only represented 



1 i( 



Island Life," 2nd ed., p. 2G1. 



