CHAP. XV OCEAXIC ISLANDS 329 



period spread over Polynesia. The extreme remoteness 

 of the islands, and the probability that they have always 

 heen more isolated than those of the Central Pacific, 

 Avould also necessarily result in an imperfect and frag- 

 mentary representation of the flora of surrounding lands. 



Goncluding Observations on the Fauna and Flora, of the 

 Sandiuich Islands. — The indications thus afforded by a 

 study of the flora seem to accord Avell 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 ; while members of the animal world, passing 

 across the sea with greater difficulty and subject to exter- 

 mination by a variety of adverse conditions, retain much 

 more of the impress of a recent state of things, with per- 

 haps here and there an indication of that ancient a23proach 

 to America so clearly shown in the Compositse and some 

 other portions of the flora. 



Genekal Remarks ox Oceaxic Islaxds. 



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 sjoecialisation and diversity from continental 

 forms which may be well explained by the known means 

 of dispersal acting through 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 



