CHAP. x;i 



THE AZORES 



255 



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 proba- 

 bility of insects as a whole reaching the islands, the chance 

 against any particular species 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, proportionately, 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 

 Brazilian elater appears to be the solitary example of a 

 living insect brought by the Gulf Stream to these remote 

 shores. The elater, having its nearest living ally in 

 Madagascar (Mastrus dolosus), cannot be held to indicate 

 any independent communication between these distant 

 islands ; but is more probably a relic of a once more wide- 

 spread type which has only been able to maintain itself in 

 these localities. Mr. Crotch states that there are some 

 species of beetles common to Madagascar and the Canary 

 Islands, while there are several genera, common to Mada- 

 gascar and South America, and some to Madagascar and 

 Australia. The clue to these apparent anomalies is found 

 in other genera being common to Madagascar, Africa, and 

 South America, while others are Asiatic or Australian. 

 Madagascar, in fact, has insect relations with every part of 



