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 ; and it is among insects, which are so ex- 
cessively varied and abundant, wdiich 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 
