chap, x.] THE PALM ARCTIC REGION. 211 



Mr. Wollaston ; that those species which possess wings in 

 Madeira, often have them rather larger than their allies in 

 Europe. These two facts were connected by Mr. Darwin, who 

 suggested that flying insects are much more exposed to be 

 blown out to sea and lost, than those which do not fly (and Mr- 

 Wollaston had himself supposed that the " stormy atmosphere ' 

 of Madeira had something to do with the matter) ; so that the 

 most frequent fliers would be continually weeded out, while the 

 more sluggish individuals, who either could not or would not 

 fly, remained to continue the race ; and this process going on from 

 generation to generation, would, on the well-ascertained princi- 

 ples of selection and abortion by disuse, in time lead to the 

 entire loss of wings by those insects to whom wings were not a 

 necessity. But those whose wings were essential to their exist- 

 ence would be acted upon in another way. All these must fly 

 to obtain their food or provide for their offspring, and those that 

 flew best would be best able to battle with the storms, and keep 

 themselves safe, and thus those with the longest and most 

 powerful wings would be preserved. If however all the indi- 

 viduals of the species were too weak on the wing to resist the 

 storms, they would soon become extinct. 1 



Now this explanation of the facts is not only simple and 

 probable in itself, but it also serves to explain in a remarkable 

 manner some of the peculiarities and deficiencies of the Madeiran 

 insect fauna, in harmony with the view (supported by the distri- 

 bution of the birds and land shells, and in particular by the 

 immigrant birds and insects of the Azores) that all the insects 

 have been derived from the continent or from other islands, by 



1 A remarkable confirmation of this theory, is furnished in the Report to 

 the Royal Society of the naturalist to the Kerguelen Island, " Transit Expe- 

 dition " — the Rev. A. E. Eaton. Insects were assiduously collected, and it 

 was found that almost all were either completely apterous, or had greatly 

 abbreviated wings. The only moth found, several flies, and numerous beetles, 

 were alike incapable of flight. As this island is subject to violent, and 

 almost perpetual gales, even in the finest season, the meaning of the extra- 

 ordinary loss of wings in almost all the insects, can, in this case, hardly be 

 misunderstood. 



