October, 1914.] 233 



saw plexippus at sea flying at a very considerable height, and observed 

 that it could settle on the surface of the water with the wings ex- 

 panded and rise again without difficulty into the air," would suggest 

 that not only is it quite able to do so with safety in calm weather, but 

 that it might even be able thus to obtain a certain amount of needful 

 rest. It is evident that a rest of this kind might be of material 

 assistance to a migrating butterfly in effecting a long sea passage. 



Dr. Scudder is not disposed, however, to admit of the butterfly 

 being able, by its unaided flight, to cross more than a moderate extent 

 of ocean. I give here his views in full (I.e. pp. 733, et seq.) : — 



" I have spoken of the extension of its natural region as one due 

 to commercial agencies, because it would seem that the distance to 

 which the insect has been carried must be due to something more than 

 its very remarkable powers of flight. The fact that the butterfly has 

 been seen flying at sea five hundred miles from land is a sufficient 

 proof of the latter, and we should be far from questioning its power 

 to compass with no very great difficulty one-half the extreme distances 

 to which we know it has been carried without power of alighting. 

 But that this should occur with a female heavy with eggs (and no 

 other supposition would permit us to understand its subsequent 

 propagation in the regions visited) is past credence ; more especially 

 as we have in the instance of its transport from the Hawaiian Islands 

 to the Caroline group an almost certain proof of the method of its 

 transport, through artificial aid. The alighting of one of these 

 butterflies laden with fertile eggs, upon some part of a vessel or within 

 its hold would by no means be a strange occurrence, and this is all 

 that is necessary to explain its transport over the wider regions. That 

 having once established itself in the Micronesian Islands it could 

 easily spread over the whole of Polynesia through the insect's ordinary 

 powers of flight, will not be questioned. But that this has taken 

 place not only within historic times, but within the last twenty or 

 thirty years, as has been shown by Semper, is an almost direct proof 

 that its first introduction to the South Seas was by artificial means ; 

 for if it could be brought about solely by the power of flight of the 

 insect, aided by the natural currents of the air, it would have happened 

 long ago, and the fact that the insect has been able to establish itself 

 wherever it chose when it got a foot-hold, and that it has not until a 

 recent period established itself, are sufficient proofs that commercial 

 agencies, so much more abundant in later times than formerly, have 

 been the great means of introducing these butterflies to the islands of 



