Iviii FAUNA HAWAIIENSIS 



explanation above mentioned. The fact of a few species of Compositae having reached 

 Hawaii in early times would account for what we now see. The Hawaiian Com- 

 positae are admittedly of American origin and it is natural that the Hawaiian group 

 and Tahiti, being nearest to the American continent, should have received thence 

 immigrants which much more distant groups of islands have not received. Nor need 

 we suppose that there has been any ' suspension ' of the means of dispersal of Com- 

 positae to Hawaii since, subsequent to the first few earliest immigrants, it must have 

 received the progenitors of Tetramalopiuni, Lipochaeta and Carnpylotheca, and probably 

 much later still, Artemisia. 



Of the age of arborescent Lobelias and their absence from the western groups, 

 the explanation is similar to that given to account for the Compositae. They also 

 are said to be of American origin, and the island groups in which they occur are just 

 those which are nearest to the American continent. We may note that the Galapagos 

 Islands, less distant from the South American coast, also have their own endemic Com- 

 positae. Birds which are supposed to have been efficient in stocking the islands with 

 plants, still annually migrate in numbers (of many species) from the American coast. 



It may be advisable to consider further and in some detail the endemic Ha.waiian 

 Compositae and Lobeliaceae, it being interesting to compare the facts in connection 

 with them with those that concern various elements of the fauna. It should be under- 

 stood that the Hawaiian Compositae as a whole (endemic and foreign) are to be 

 compared, not with a compact tribe such as the Anchomenine Carabidae, above 

 mentioned, but rather with the Hawaiian Carabidae as a whole. 



The four genera Reniya, Wilkesia, Argyroxipliiimt and Hesperomannia are supposed 

 by botanists to be extremely ancient forms in the flora, and, on account of their having 

 only two^ species each, to be in a decadent stage and becoming extinct. Their antiquity 

 as elements of the Hawaiian flora is, I suppose, mainly based on their structural isola- 

 tion, as compared with foreign forms, but it is said to be also shown by the paucity 

 of the existing species and their restricted range in the islands. Although a limited 

 number of species in an endemic genus is sometimes found, where we suspect that 

 genus to be an ancient component of the flora or fauna, yet more often the oldest 

 elements of the flora are certainly those genera (or groups of allied genera) with the 

 most numerous species and the widest distribution, as is also the case in the fauna. 

 Therefore the primary consideration must be the structural peculiarity of the plants 

 themselves. But we must not altogether overlook the possibility of the discovery of 

 forms in America, more closely allied to these isolated Hawaiian species than those 

 yet known. Besides these supposedly ancient genera, we have Raillardia and Dubantia, 

 together comprising about a score of species, the genera being related to one another 

 and also allied to the genus Raillardella of the Sierra Nevada. Consequently these 

 genera and their species may well be supposed to have originated from an anciently 

 ' According to Hillebrand's Flora of the Hawaiian Islands. 



