298 ISLAND LIFE paet ii 



Insects — ColcG2:)tcra. — The total number of species of 

 beettes hitherto observed at St. Helena is 203, but of these 

 no less than seventy-four are common and wide-spread 

 insects, which have certainly, in Mr. Wollaston's opinion, 

 been introduced by human agency. There remain 129 

 which are believed to be truly aborigines, and of these all 

 but one are found nowhere else on the globe. But in 

 addition to this large amount of specific peculiarity (perhaps 

 unequalled anywhere else in the world) the beetles of this 

 island are equally remarkable for their generic isolation, 

 and for the altogether exceptional proportion in which the 

 great divisions of the order are represented. The species 

 belong to thirty -nine genera, of which no less than twenty- 

 five are peculiar to the island ; and many of these are 

 such isolated forms that it is impossible to find their allies 

 in any particular country. Still more remarkable is the 

 fact, that more than two-thirds of the whole number of 

 indigenous species are Rhyncophora or weevils, while more 

 than two-fifths (fifty-four species) belong to one family, the 

 Cossonidse. Now although the Rhyncophora are an 

 immensely numerous group and always form a large por- 

 tion of the insect population, they nowhere else apj^roach 

 such a proportion as this. For example, in Madeira they 

 form one-sixth of the whole of the indigenous Coleoi^tera, 

 in the Azores less than one-tenth, and in Britain one- 

 seventh. Even more interesting is the fact that the twenty 

 genera to which these insects belong are every one of 

 them peculiar to the island, and in many cases have no 

 near allies elsewhere, so that we cannot but look on this 

 group of beetles as forming the most characteristic portion 

 of the ancient insect fauna. Now, as the great majority 

 of these are wood borers, and all are closely attached to 

 vegetation and often to particular species of plants, we 

 might, as Mr. Wollaston well observes, deduce the former 

 luxuriant vegetation of the island from the great pre- 

 ponderance of this group, even had we not positive evidence 

 that it was at no distant epoch densely forest-clad. We 

 will now proceed briefly to indicate the numbers and 

 peculiarities of each of the families of beetles which 

 enter into the St. Helena fauna, taking them, not in 



