XX THE AGE OF FERNS 229 



in the development of new specific and generic types, tiie Hawaiian 

 vascular cryptogams are far exceeded by the flowering plants where 

 the proportion of endemic species amounts to 80 per cent. We have 

 no reason to believe that the winds, to which the ferns and lycopods 

 chiefly owe their dispersal, are less effective now in carrying their 

 spores than they were in the earliest era of the floral history of 

 Hawaii or in the intervening periods. In the course of ages the 

 winds have been more uniform in their action as plant-dispersers 

 even than the currents, and certainly far more than birds. 



On the other hand, in the case of the Hawaiian flowering plants 

 that depend on the varying influence of the migrant bird, the 

 agency of dispersal has often been suspended altogether, and far 

 greater differentiation or departure from the original type has 

 resulted, the amount of change often reaching to the value of 

 a generic distinction. It is a question, however, whether the 

 isolation of the Hawaiian Islands is to be entirely connected with 

 their mid-oceanic position. It will be shown in Chapter XXXIII. 

 that effects almost as great have been produced in continental 

 regions and in continental islands, and that the isolated situation of 

 Hawaii has not induced but has intensified these results. In the 

 later eras of plant-life a process of segregation has been ever active 

 throughout the tropical world whether in the case of an elevated 

 oceanic island or of a mid-continental mountain. 



The following are some of the principal points that have been 

 emphasised in the foregoing discussion of the ferns and lycopods of 

 the Hawaiian, Fijian, and Tahitian Islands : — 



(a) In all three groups the vascular cryptogams (ferns and 

 lycopods) have been largely supplied from the warmer regions 

 of the Old World. But whilst in the South Pacific the migration 

 has been mainly from Fiji eastward to Tahiti, it is probable 

 that Hawaii in the North Pacific has been in part independently 

 stocked. 



{b) Whilst in Hawaii many peculiar species of ferns and 

 lycopods have been developed, in Fiji and Tahiti there have been 

 comparatively few. 



(c) Whilst there has been more or less free immigration into 

 Fiji and Tahiti there has been comparative isolation in Hawaii. 

 Though the areas of the Fijian and Hawaiian archipelagoes are 

 about the same, Fiji possesses at least half as many species 

 again as Hawaii ; but Hawaii owns three or four times the number 

 of peculiar species. 



(d) Though the land-area of the Tahitian region does not 



