254 ISLAND LIFE part ii 



Elaterid^. 



Heteroderes azoriciis Allied to a Brazilian species. 



Elastrus dolosus Belongs to a peculiar Madagascar genus ! 



Melyrid^. 

 Attains miniaticollis Allied to a Canarian species. 



Rhyncophora. 



Phloeophagus variabilis ...Allied to European and Atlantic species. 



Acalles droueti A Mediterranean e nd Atlantic genus. 



Laparoccrus azoricus Allied to Madeiran species. 



Asynonychun godmansi ...A ■peculiar genus, allied to Brachyderes, oi the 



south of Europe. 

 Neocnemis occidentalis ... A peculiar genus, allied to the European genus 

 StropJiosomus. 



Heteromera. 

 Helops azoricus Allied to H. mdcaniis of Madeira. 



Staphylinid^. 

 Xenomma melanocephala.. Allied to X. filiforme from the Canaries. 



This greater amount of speciality in the beetles than in 

 the birds may be due to two causes. In the first place 

 many of these small insects have no doubt survived the 

 glacial epoch, and may, in that case, represent very ancient 

 forms which have 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 



