XXXIV GENERAL ARGUMENT AND CONCLUSION 517 



Pacific islands here come into prominence. There is the Hawaiian 

 difficulty, where with genera containing both shore and inland 

 species only the last are found in Hawaii ; and although the shore- 

 plants are known to be dispersed by the current, the inland plants 

 display little or no capacity for this or any other mode of dispersal. 

 Here belong the Leguminous genera Canavalia, Erythrina, Mezo- 

 neuron, and Sophora, and the Apocynaceous genus Ochrosia ; and 

 it is assumed that the inland Hawaiian species are derived from a 

 current-dispersed shore-plant that has since disappeared from the 

 group. The Fijian difficulty is displayed in those genera where 

 both coast and inland species occur in the islands, but no known 

 existing means of dispersal across an ocean can be postulated for 

 the inland plants, though the shore species are distributed by the 

 currents. Of such genera Pandanus is the best example, and it is 

 pointed out that this genus presents the same difficulty in the 

 Mascarene Islands, in which case the agency of the extinct 

 Columbai is invoked. 



As illustrating the methods of observation and experiment 

 employed by the author, the Leguminous shore-plants Afzelia 

 bijuga, Cassalpinia bonducella, and Entada scandens are dis- 

 cussed at length ; and in the chapters on the enigmas of the 

 Leguminosse in the Pacific it is pointed out that the behaviour of 

 the plants of this order is a source of much perplexity, and that 

 they conform to no single rule of dispersal. 



Coming to the inland plants of this region, the Fijian, Tahitian, 

 and Hawaiian groups are taken as the chief centres of distribution 

 in the Pacific. After discussing the relative sizes, the altitudes, 

 and the climates of these three archipelagoes, it is shown that 

 Hawaii, on account of the far greater altitude of the islands, is 

 characterised by a special mountain flora, and that it is comparable 

 with Fiji, and to a great extent also with Tahiti, only as regarding 

 the plants of the levels below 4,000 or 5,000 feet. 



The first era of the plant-stocking is designated the Age of 

 Ferns, and it is observed that, whilst in Hawaii nearly half of the 

 ferns and lycopods are peculiar to that group, very few new species 

 have been developed in the Fijian and Tahitian regions. 



The next era in the floral history of these islands is represented 

 in the first era of the flowering plants. This is indicated by the 

 endemic genera, which are particularly numerous in Hawaii, 

 relatively scanty in Fiji, and very few in Tahiti. On account of 

 their preponderance, the era is designated the Age of Compositse 

 and Lobeliaceae. The genera of these two orders, though mainly 



