390 A NATURALIST IN THE PACIFIC chap. 



which are often quite as well fitted for over-sea transport as are 

 several of the plants already established there. But it should be 

 remembered that crowding out would often come into play in such 

 a contracted region. The area, however, has been very generously 

 dealt with as regards plant genera. Though the total land-surface 

 cannot be more than one-fourth or one-third that of Fiji or Hawaii^ 

 it possesses more than half the number of genera found in Fiji, and 

 four-fifths of the number found in Hawaii. 



Fiji 



The Fijian Genera not found in either the Tahitian or 

 Hawaiian Regions 



We have already in some degree dealt with Fiji in so far as the 

 partial dispersal of genera over the Pacific islands is concerned. 

 We have seen that it possesses very i&w genera (not a score in all) 

 in common with Hawaii that are not found in the Tahitian region, 

 and it is assumed that in most cases such genera reached Hawaii 

 independently and not through the South Pacific. On the other 

 hand, excluding the grasses, sedges, and vascular cryptogams, Fiji 

 owns in common with Tahiti between sixty and seventy genera 

 that do not occur in Hawaii. This shows unmistakably the trend 

 of plant migration in the Pacific islands. Several interesting 

 features in plant-distribution have been already brought out, and 

 notably the fact that Indo-Malayan genera with large seeds or 

 " stones " an inch in size have been arrested in the Fijian region 

 in their passage into the South Pacific. Thus Canarium, 

 Dracontomelon, Myristica, and Sterculia have not extended east- 

 ward of the Fijian area. 



Yet a very large proportion of the Fijian genera, quite half of 

 the total number, are not represented either in the Tahitian or in the 

 Hawaiian region ; and of many of them it is obvious that they are 

 as well fitted to be carried over the Pacific as are those that have 

 actually reached Tahiti and Hawaii. Take, for instance. Begonia, 

 which has not extended east of Fiji, though Hillebrandia, a genus 

 of the order, is peculiar to Hawaii. Nor can we explain why with 

 three genera like Geissois, Dolicholobium, and Alstonia, possessing 

 seeds dispersed by the winds, only the last-named has passed 

 beyond Fiji. However, as before remarked, it is probable that lack 

 of opportunity rather than capacity for dispersal has determined the 

 matter, and we must, therefore, assume that many of the genera have 



