248 A NATURALIST IN THE PACIFIC chap. 



(2) This great preponderance of peculiar species and genera in 

 Hawaii is not to be connected with the relative antiquity of the 

 group but with its degree of isolation. 



(3) The earliest stage of the flowering plants of the islands 

 of Hawaii and of Eastern Polynesia (the Tahitian region) is 

 indicated by the endemic genera, particularly those of the 

 Compositae and Lobeliaceae. Such genera are numerous in 

 Hawaii, and occur also in the Tahitian region, as in Tahiti and 

 Rarotonga ; but do not exist in the groups of the Fijian region 

 (Fiji, Tonga, and Samoa). 



(4) The endemic genera of the Hawaiian Compositae are 

 mainly American in their affinities. The relationship of the 

 solitary Tahitian genus (Fitchia) is still a subject of discussion. 



(5) In the Hawaiian Islands, as well as in Tahiti and Raro- 

 tonga, the plants of the endemic genera of Compositae are, as a rule, 

 arborescent or shrubby ; and in the first two localities they arc 

 mainly restricted to the higher levels. 



(6) In discussing the mode of dispersal of the achenes of the 

 original genera we have also to explain why the process of dis- 

 persal has been in the main suspended. 



(7) It is shown that the achenes of these early Compositae were 

 in all probability suited for dispersal in birds' plumage. 



(8) Yet the isolating influence that cut off these genera from 

 the outside world has, in later ages, been active within the limits 

 of the Hawaiian archipelago, with the result that half the species 

 are not found in more than a single island. Inter-island dispersal 

 has, therefore, been also largely suspended. 



(9) The absence of endemic genera of Compositae from Fiji, 

 Tonga, and Samoa cannot be attributed to unsuitable climatic 

 conditions connected with the relatively low elevation of those 

 islands as contrasted with those of Hawaii, since a species of 

 Fitchia abounds in Rarotonga, which is not far over 2,000 feet 

 in elevation. Shrubby and arborescent Compositae of peculiar 

 types also occur in the Galapagos and other tropical islands 

 not more elevated than the Fijis. 



(10) These endemic genera are the remains of an ancient 

 Composite flora in the islands of the tropical Pacific, and ages 

 have elapsed since the severance of their connections with regions 

 outside. 



(n) According to Mr. Bentham the Compositae were distributed 

 over Africa, West America, and possibly Australia, at an early 

 period, but subsequent to the differentiation of the tribes of 



