274 ISLAND LIFE 



groups — wrens, tits, creepers, and nuthatches — are absent ; 

 while the number of annual visitors is greater in propor- 

 tion as the migratory habits and prevalence of storms 

 afford more efficient means for their introduction. 



We find also, that these great distances do not prevent 

 the immigration of some insects of most of the orders, 

 and especially of a considerable number and variety of 

 beetles ; while even land-shells are fairly represented in 

 both islands, the large proportion of peculiar species 

 clearly indicating that, as we might expect, individuals of 

 this group of organisms arrive only at long and irregular 

 intervals. 



Plants are represented by a considerable variety of orders 

 and genera, most of which show some special adaptation 

 for dispersal by wind or w^ater, or through the medium of 

 birds ; and there is no reason to doubt that besides the 

 species that have actually established themselves, many 

 others must have reached the islands, but were either not 

 suited to the climate and other physical conditions, or did 

 not find the insects necessary to their fertilisation, and 

 were therefore unable to maintain themselves. 



If now we consider the extreme remoteness and isolation 

 of these islands, their small area and comparatively recent 

 origin, and that, notwithstanding all these disadvantages, 

 they have acquired a very considerable and varied flora 

 and fauna, we shall, I think, be convinced, that with a 

 larger area and greater antiquity, mere separation from a 

 continent by many hundred miles of sea would not prevent 

 a country from acquiring a very luxuriant and varied flora, 

 and a fauna also rich and peculiar as regards all classes 

 except terrestrial mammals, amphibia, and some groups of 

 reptiles. This conclusion will be of great importance in 

 those cases where the evidence as to the exact origin of 

 the fauna and flora of an island is less clear and satisfactory 

 than in the case of the Azores and Bermuda. 



