376 A NATURALIST IN THE PACIFIC chap. 



Kleinhovia, Melochia, and Commersonia, that are represented in 

 P'iji but not in Hawaii, cannot be discussed together. With 

 Sterculia is concerned the dispersal by birds of large seeds, an inch 

 in length, not particularly well protected, the genus being confined 

 to Fiji alone of all the oceanic Pacific groups. Heritiera is only 

 represented by a littoral species, the large fruits of which are 

 carried great distances by the currents ; and no other agency 

 of dispersal is here possible. The last three genera are distributed 

 over the South Pacific, their relatively small seeds being probably 

 in the main dispersed by granivorous birds; whilst the setose fruits 

 of Commersonia may have been at times transported in birds' 

 plumage. 



It is more legitimate, perhaps, to speak collectively of the 

 orders Meliaceee and Melastomaceje as absent from Hawaii ; but 

 even here the issue raised is one concerned rather with oppor- 

 tunities than with capacities for dispersal. Several years ago, 

 M. Casimir de Candolle remarked that " it is hardly credible 

 that the Meliacefe should be entirely absent from the Sandwich 

 archipelago" {Trans. Linn. Soc. Bot., vol. i. 1880). Yet it can 

 scarcely be said that this is a matter connected with means of 

 dispersal. Amongst the Meliaceous genera represented in Fiji, 

 Vavaea and Aglaia have a berry, Melia has a drupe, and Dysoxy- 

 lum has a capsule. So again with the Melastomaceae ; it possesses 

 at least six genera in Fiji, two in Tahiti, and none in Hawaii. 

 Whilst the genera Melastoma and Medinilla have baccate fruits 

 with minute seeds, Astronia has a capsule with similar seeds, and 

 Memecylon has a single-seeded berry. Since, however, minute 

 seeds are most typical of the order, those of Melastoma denti- 

 culatum being about one-fiftieth of an inch or '5 mm. in size, 

 it would seem that this character has not aided its dispersal in the 

 Pacific so far as Hawaii is concerned. F"rom the circumstance that 

 berries, drupes, and capsules are represented in these two Fijian 

 orders we may form the opinion that their non-occurrence in 

 Hawaii is due not so much to lack of capacities for dispersal as to 

 failure of opportunities. 



This opinion is much strengthened when we come to deal with 

 the individual genera, where the predominant cause of the absence 

 of so many Fijian genera from Hawaii is concerned with the 

 failure of the agencies of dispersal. It is not a question of a 

 difference in size between the groups, since, although the surface- 

 area is approximately the same in both groups, Hawaii possesses 

 only two-thirds of the number of genera occurring in Fiji. It is not 



