86 



importation from the European continent, and as vet in 

 a transition state? an idea which the smallness of its 

 wings, as compared with those of its British analogues, 

 wonld seem rather to corroborate. 



But, if this slight increase of stature would appeal- 

 generally to accompany that gradual extinction of the 

 powers of flight which isolation is apt to induce, it 

 follows, on the other hand (as indeed I have lately 

 intimated), that where wings are so essential to the con- 

 tinuance of a species that they cannot, without its posi- 

 tive destruction, be taken from it, the primary effect of 

 isolation, namely a diminution of bulk, will for the 

 most part happen instead. As this fact, however, has 

 been already commented upon, we will not discuss it 

 afresh. 



AVhy it is, in the Insecta, that islands* should pre- 

 dispose to an apterous state more than continents, it is 

 not easy to speculate. Mr. Darwin has indeed suggested, 

 and with much apparent reason, that, were wings fully 

 developed, the indiscriminate use of them might lead to 

 unhappy results, by tempting the creatures to venture 

 too far from their native rocks ; and that, therefore, this 

 partial decay is, under such circumstances, a wise pro- 

 vision in their favour : whilst it has been urged, on the 

 other hand, that since insular species are at all times 

 liable during heaw scales to be blown out to sea, they 



4- O l 



* I am informed by Dr. Hooker, that the only two insects (belong- 

 ing respectively to the orders Coleoptera and Lepidoptera) which 

 he detected iu Kerguelen's Laud were wingless. 



