Fbbeuaey 28, 1896.] 



SGIENGE. 



313 



edge of the sea. They are provided with 

 small triangular vestigial wings and bal- 

 ancers." They cannot fly, but seem to use 

 the wings in jumping, which they do with 

 great activity, making it quite difficult to 

 catch them. They do not appear to jump 

 in any definite direction, but spring into the 

 air, buzzing the small winglets with great 

 activity, and seem to trust to chance for a 

 spot on which to alight, tumbling over and 

 over in the air. I never observed them 

 jumping when undisturbed. 



Dr. Kidder adds that ' the only flying in- 

 sect observed by me while on the island ' 

 (he apparently momentarily overlooked the 

 larger flying weevil) was a small gnat. Mr. 

 Eaton also describes a tipulid {Halyritm 

 amphihius) with imperfect or abortive wings. 



Of the exact relationship and origin of 

 this restricted island fauna, but little in the 

 present state of our knowledge can be said. 

 To which family the moth belongs I am at 

 present unable to state. As to the Diptera 

 they are mostly muscidae, and this family 

 is more largely represented in the Arctic re- 

 gions and on Alpine summits the world over 

 than any other group. But this is not the 

 case with the Coleoptera ; of this order the 

 Carabidae are most numerously represented 

 in Arctic and Alpine regions, and they are 

 common in Chili, while the weevils are the 

 least in number of species in Arctic regions. 

 And yet out of the eight species of beetles in- 

 habiting Kerguelen Island, six are weevils, 

 a group most numerously represented in 

 subtropical and tropical regions. This would 

 seem to indicate that this island was colo- 

 nized by waifs from the land to the westward, 

 whether from Australia, Africa or South 

 America, I should not dare to say. On the 

 other hand, the land plants and the marine 

 fauna appear to have elements more in com- 

 mon with Patagonia and Fuegia, and this 

 may be explained by the cold polar current 

 which is said to flow from the Antarctic re- 

 gion towards Cape Horn. 



Darwin has, in his Origin of Species, 

 called attention to a remarkable feature of 

 the Madeiran Coleoptera, i. e., the unusual 

 prevalence of apterous or wingless species. 

 ISTo less than twenty-two genera which are 

 usually or sometimes winged in Europe 

 having only wingless species in Madeira. 

 Mr. Wallaston discovered that 200 beetles 

 out of 550 species then known to inhabit 

 Madeira are so far deficient in wings that 

 they cannot fly. These facts led Darwin to 

 believe "that the wingless condition of so 

 many Madeira beetles is mainly due to the 

 action of natural selection, but combined 

 probably with disuse . For during many suc- 

 cessive generations each individual beetle 

 which flew least, either from its wings hav- 

 ing been ever so little less perfectly devel- 

 oped or from indolent habits, will have had 

 the best chance of surviving from not being 

 blown out to sea ; and, on the other hand, 

 those beetles which most readily took to 

 flight could oftenest have been blown to 

 sea and thus have been destroyed." On the 

 other hand, the wings of the flower-feeding 

 Coleoptera and Lepidoptera, which are hab- 

 itually on the wing, 'have, as Mr. Wallaston 

 suspects, their wings not at all reduced, 

 but even enlarged.' He adds that the pro- 

 portion of wingless beetles is larger on the 

 exposed island Desertas than in Madeira it- 

 self Mr. Wallace, in his great work, ' The 

 Greographical Distribution of Animals ' (ii., 

 pp. 211), cites the wingless insects of Ker- 

 guelen Island as a remarkable confirmation 

 of this theory. 



The poverty of the land fauna of Ker- 

 guelen Island, and the reduction in the 

 wings of the insects, are so intimately cor- 

 related with the extremely unfavorable cli- 

 matic condition under which these animals 

 exist that the loss or reduction in the size of 

 the wings may, we venture to suggest, be 

 explained as the result of the direct action 

 of some of the primary factors of organic 

 evolution. 



