CHAP. XV THE SANDWICH ISLANDS 329 



period spread over Polynesia. The extreme remoteness 

 of the islands, and the probability that they have always 

 been more isolated than those of the Central Pacific, 

 would also necessarily result in an imperfect and frag- 

 mentary representation of the flora of surrounding lands. 



Concluding Observations on the Fauna and Flora of the 

 Sandwich Islands. — The indications thus afforded by a 

 study of the flora seem to accord well with what we know 

 of the fauna of the islands. Plants having so much 

 greater facilities for dispersal than animals, and also having 

 greater specific longevity and greater powers of endurance 

 under adverse conditions, exhibit in a considerable degree 

 the influence of the primitive state of the islands and their 

 surroundings, and the same is the case with the birds ; 

 while other members of the animal world, passing across 

 the sea with greater difficulty and subject to extermination 

 by a variety of adverse conditions, retain more of the im- 

 press of a recent state of things, with here and there, 

 especially in the birds, an indication of that ancient 

 communication with America so clearly shown in the Com- 

 positse and some other portions of the flora. 



General Remarks on Oceanic Islands. 



We have now reviewed the main features presented by 

 the assemblages of organic forms which characterise the 

 more important and best known of the Oceanic Islands. 

 They all agree in the total absence of indigenous mam- 

 malia and amphibia, while their reptiles, when they possess 

 any, do not exhibit indications of extreme isolation and 

 antiquity. Their birds and insects present just that 

 amount of specialisation and diversity from continental 

 forms which may be well explained by the known means 

 of dispersal acting througlx long periods ; their land 

 shells indicate greater isolation, owing to their admittedly 

 less effective means of conveyance across the ocean ; while 

 their plants show most clearly the effects of those changes 

 of conditions which we have reason to believe have 

 occurred during the Tertiary epoch, and preserve to us in 

 highly specialised and archaic forms some record of the 

 primeval immigration by which the islands were originally 



