XII THE COLEOPTERA OF MADEIRA 265 



South American species, probably introduced in the 

 floating timber, though they may also have come with 

 living plants, which are often brought from Bahia. Two 

 species, however, are peculiar, and one is closely allied to a 

 Brazilian species, so that it must have been introduced by 

 natural agencies before the settlement of the island ; the 

 other is of a genus confined to Madagascar. 



Now it is a suggestive fact that the Mozambique 

 current, bending round the Cape of Good Hope to the 

 Equator, is one of the sources of the Gulf-stream ; so that 

 it is not impossible that a tree, carried down by a flooded 

 river on the west coast of Madagascar, might ultimately 

 reach the Azores. That it should convey living larvae or 

 pupa3 of Elaters may also not be impossible ; and if such 

 a log reached the Azores but once in ten thousand years, 

 and but one log in a thousand should convey living Elaters, 

 we should still, if the calculations of geologists have any 

 approximate value whatever, be far within the epoch of 

 existing genera, and even of most existing species. A 

 relation so isolated and extraordinary as that between a 

 single insect of the Azores and those of Madagascar, may 

 well be due to a concurrence of events as rare and 

 improbable as this seems to be. 



The Azores, and in a less degree the Madeiras, appear 

 to me to teach us this important lesson in the laws of 

 distribution of birds and insects, — that it has been de- 

 termined neither by the direction of ocean currents nor by 

 that of the most prevalent winds, but almost wholly by more 

 exceptional causes such as storms and hurricanes, which 

 still continue to bring immigrants from the nearest lands. 



Mr. Murray's argument for a land-connection between 

 the various Atlantic islands, from the Azores to the Cape 

 de Verdes, and even to St. Helena, has perhaps more to 

 be said for it ; but I do not think that the facts require 

 anything beyond the extension of each group into one or 

 more considerable islands. Such an extension is perhaps 

 indicated by the comparatively elevated submarine bank 

 on which each group stands ; and it is evident that more 

 extended land-surfaces would not only bring the groups 

 nearer to each other, but, by offering a much greater length 



