Ixvi 



Now we can hardly doubt that these same storms also bring 

 Coleoptera and other insects to the Azores, though it may be 

 more rarely and in smaller numbers than in the case of birds ; 

 and the large proportion of European species will then be very 

 intelligible. The same explanation is suggested by the propor- 

 tions of the most important groups, for while (after deducting all 

 those species believed to have been introduced by man) the 

 Geodephaga and Brachelytra are by far the most numerous, the 

 Rhynchophora and the Heteromera are exceedingly few, a dis- 

 tribution which corresponds with their respective powers of flight. 

 It is also a very important fact that only four non-introduced 

 species can be traced to an American origin, while more than a 

 hundred are European ; since it shows of how little importance 

 are ocean currents as a means of .conveying insects over a wide 

 extent of sea ; whereas the great mass of the non-introduced species 

 have evidentl}'- passed through the air, aided by their powers of 

 flight, for a distance of about a thousand miles from Europe. 

 The Azorean Elateridae form a curious feature of its fauna, con- 

 sidering that the whole family is almost absent from Madeira and 

 the Canaries. Of the six species two are European (one specially 

 Portuguese), so that they may have been introduced with living 

 plants. Two are common 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 Mada- 

 gascar, might ultimatel}' reach the Azores. That it should conve}^ 

 living larvae or pupse 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 convej'' 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 extra- 

 ordinary as that between a single insect of the Azores and those 



