ISLAND LIFE. 



[part II. 



Concluding Observations on the Fauna and Flora of the Sand- 

 wich Islands. — The indications thus afforded by a study of the 

 flora seem to accord well v/ith 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 difiiculty and 

 subject to extermination by a variety of adverse conditions, 

 retain much more of the impress of a recent state of things, 

 with perhaps here and there an indication of that ancient 

 approach to America so clearly shown in the Compositae and 

 some other portions of the flora. 



Genei'al Eeniarhs 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 indi- 

 genous mammalia 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 best 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 ocea,n; 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 Vvliich the islands were originally 

 clothed with vegetation. But in every case the series of forms 

 of life in these islands is scanty and imperfect as compared with 

 far less favourable continental areas, and no one of them presents 

 such an assemblage of animals or plants as we always find in an 

 island which we know has once formed part of a continent. 



It is still more important to note that none of these oceanic 

 archipelagoes present us with a single type which we may 

 suppose to have been preserved from Mesozoic times ; and this 



