346 



ISLAND LIFE. 



[part II. 



never been found on the continent. We have also the curious 

 fact of our outlying islands, such as the Shetland Isles, the Isle 

 of Man, and the little Lundy Island, possessing each some 

 peculiar forms which, certainly, do not exist on our principal 

 island which has been so very thoroughly worked. Analogy, 

 therefore, would lead us to conclude that many other species 

 would exist on our islands and not on the continent ; and when 

 we find that a very large number (150) in three orders only, are 

 so recorded, we may I think be sure that a considerable portion 

 of these (though how many we cannot say) are really endemic 

 British species. 



The general laws of distribution also lead us to expect such 

 phenomena. Very rare and very local species are such as are 

 becoming extinct ; ?jid it is among insects, which are so ex- 

 cessively varied and abundant, which present so many isolated 

 forms, and which, even on continents, afford numerous examples 

 of very rare species confined to restricted areas, that we should 

 have the best chance of meeting with every degree of rarity 

 down to the point of almost complete extinction. But we 

 know that in all parts of the world islands are the refuge of 

 species or groups which have become extinct elsewhere; and it 

 is therefore in the highest degree probable that some species 

 which have ceased to exist on the continent should be preserved 

 in some part or other of our islands, especially as these present 

 favourable climatic conditions such as do not exist elsewhere. 



There is therefore a considerable amount of harmony in the 

 various facts adduced in this chapter, as well as a complete 

 accordance with what the laws of distribution in islands would 

 lead us to expect. In proportion to the species of birds and 

 fresh-water fishes, the number of insect-forms is enormously 

 great, so that the numerous species here recorded as not yet 

 known on the continent are not to be wondered at ; while it 

 would, I think, be almost an anomaly if, with peculiar birds 

 and fishes there were not a fair proportion of peculiar insects. 

 Our entomologists should, therefore, give up the assumption 

 that all our insects do exist on the continent, and will sometime 

 or other be found there, as not in accordance with the evidence ; 

 and when this is done, and the interesting peculiarities of some 



