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Show 34() ISLAND LIFK (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 (1.50) in three orders only, arc 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 arc such as arc becoming extinct; and it is among insects, which arc so excessively 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; aml it is therefore in the highest degree probable that some species which have ceased to exist on the continent should be preservcrl in some part or other of our islands, especially as these prescut favourable climatic conditions such as do not exist elsewhere. There is therefore a considerable amount of harmony in tho 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 ~nAP. xvr.] THE BRITISH ISLES. 347 of our smaller islands are remembered, the study of our native animals and plants, in relation to those of other countries, will acquire a new interest. The British Isles are said to consist of more than a thousand islands and islets. How many of these have ever been searched for insects? With the case of Lundy Island before us, who shall say that there is not yet scope for extensive and interesting investigations into the British fauna and flora? |