242 A NATURALIST IN THE PACIFIC chap. 



and also high up in Tahiti (Moseley), its agency is not unlikely. 

 I am inclined to think, however, that birds like the petrels and 

 puffins, that in nesting burrow in the ground, choosing places where 

 the vegetation is thickest, and where they would be likely to get 

 seeds on their feathers, would be more efficient agents. This is 

 the view expressed by Prof. Moseley in Wallace's Island Life, 

 p. 250. He considered that albatrosses, petrels, and puffins have 

 played a great part in the distribution of plants, and to some 

 degree especially account for the otherwise difficult fact that widely 

 distant islands in tropical seas have similar mountain plants. 

 Birds, he says, that in high latitudes, as at Tristan da Cunha and 

 Kerguelen, often burrow near the sea-level, in the tropics choose 

 the mountains for their nesting-place ; and he refers to a puffin 

 that nests on the top of one of the high mountains of Viti Levu at 

 an altitude of 4,000 feet, to a petrel nesting among ferns at Tahiti 

 at an elevation of 4,400 feet, and to another petrel breeding in like 

 manner in the high mountains of Jamaica at a height of several 

 thousand feet above the sea. He gives point to these interesting 

 remarks, which might be supplemented by data from other parts of 

 the world, by observing that it is not necessary that the same 

 species should now cover the range of the plants concerned. The 

 ancestor of the species might have carried the seeds, and the 

 range of the genus is alone sufficient. It may be added that, as I 

 have shown in Chapter XXXIII., sea-birds have been far more 

 active agents in the distribution of plants than many people might 

 imagine. The more recent observations of Ekstam in Spitzbergen 

 have thrown considerable light on this subject. 



Having in the first place formed the opinion that the achenes 

 of the early Hawaiian Compositae are suited for dispersal by birds, 

 and then shown that sea-birds were probably the principal agents, 

 we are met with the curious difficulty that in the case of the early 

 Hawaiian genera of Compositae the complete suspension for ages 

 of the means of dispersal is involved in the circumstances that 

 these genera are confined to the Hawaiian group. We can attri- 

 bute to the agency of existing sea-birds the occurrence of the 

 genus Lagenophora in the uplands of Hawaii, on the mountain- 

 tops of Fiji, and in Australia and New Zealand ; but the agency of 

 birds as at present in operation does not assist us except indirectly 

 in the case of the genera restricted to Hawaii or to Tahiti. Is it 

 possible, we may inquire, to penetrate this mystery } Why, we 

 may ask with Mr. Hemsle}^ has the agency ceased acting, and why 

 have its operations been confined to the conveyance of seeds to 



