246 
ISLAND LIFE. 
[part II. 
become extinct in their native country ; and in the second place, 
insects have many more chances of reaching remote islands than 
birds, for not only may they be carried by gales of wind, but 
sometimes, in the egg or larva state or even as perfect insects, 
they may be drifted safely for weeks over the ocean, buried in 
the light stems of plants or in the solid wood of trees in which 
many of them undergo their transformations. Thus we may 
explain the presence of three common South American species 
(two elaters and a longicorn), all wood-eaters, and therefore 
liable to be occasionally brought in floating timber by the Gulf 
Stream. But insects are also immensely more numerous in 
species than are land-birds, and their transmission would be in 
most cases quite involuntary, and not dependent on their own 
powers of flight as with birds; and thus the chances against the 
same species being frequently carried to the same island would 
be considerable. If we add to this the dependence of so many 
insects on local conditions of climate and vegetation, and their 
liability to be destroyed by insectivorous birds, we shall see that, 
although there may be a greater probability of insects as a whole 
reaching the islands, the chance against any particular insect 
arriving there, or against the same species arriving frequently, 
is much greater than in the case of birds. The result is, that 
(as compared with Britain for example) the birds are, pro- 
portionately, much more numerous than the beetles, while the 
peculiar species of beetles are much more numerous than among 
birds, both facts being quite in accordance with what we know 
of the habits of the two groups. We may also remark, that the 
small size and obscure characters of many of the beetles renders 
it probable that species now supposed to be peculiar, really 
inhabit some parts of Europe or North Africa. 
It is interesting to note that the two families which are pre- 
eminently wood, root, or seed eaters, are those which present the 
greatest amount of speciality. The two Elateridse alone exhibit 
remote affinities, the one with a Brazilian the other with a 
Madagascar group ; while the only peculiar genera belong to the 
Rhyncophora, but are allied to European forms. These last 
almost certainly form a portion of the more ancient fauna of the 
islands which migrated to them in pre-glacial times, while the 
