EUPLOEINAE: ANOSIA PLEXIPPUS. 731 



had been introduced. We next find it 1857 as far away as the Island of 

 Ponape, one of the Caroline Islands in Micronesia, a distance of another two 

 thousand miles or so from the Hawaiian Islands. This fact we also owe to 

 Dr. Gulick's personal testimony. He was for some time a resident of 

 Ponape, and the butterfly was first seen by him in the year mentioned, 

 not long after he had discovered several young milk weeds which had 

 sprung up in earth in which various other plants had been brought 

 from the Hawaiian Islands in a Wardian case. The plants were brought 

 in a missionary vessel which sailed from Honolulu, and on its way to 

 Ponape touched only at Apaiang of the Gilbert Islands and Ebon of the 

 Marshall Group, both low coral atolls, and at Kusaie which is of basaltic 

 formation and richly clothed with verdure, but where the butterfly did not 

 then occur. It is evidently impossible that in a voyage consisting in the 

 whole of fifty-four days, the insect in any stage or stages could have been 

 transported in the Wardian case itself, for it easily undergoes all its trans- 

 formations in warm regions in a month or five weeks at most. If the but- 

 terflies were introduced at that time, as there is every reason to believe 

 from Dr. Gulick's accounts, there seems no other supposition possible than 

 that an impregnated female flew into the hold of the vessel wdiile lading at 

 Honolulu, and was carried perforce to Ponape ; or, possibly, a pair of but- 

 terflies. It would certainly be absurd to suppose that a gravid female 

 could have flown over two or three thousand miles of ocean, and in 

 addition have appeared in Ascension Island almost simultaneously with a 

 few plants of Asclepias. As the butterflies pass the entire winter in hiber- 

 nation and then lay eggs in the spring, there is nothing in any way really 

 surprising in Dr. Gulick's statements, unless it be impossible for an im- 

 pregnated female to live in enforced hibernation a couple of months with- 

 out laying ; when it w^ould be necessary to suppose a pair to have been 

 transported, which would of course be more extraordinary. 



Granting our explanation to be just, it is highly probable that it 

 was from this single ancestor, or pair, that the swarms which have 

 now spread over the entire South Seas, in many of which it is the 

 commonest butterfly known, have sprung. Our knowledge of the period 

 and extent of this later distribution we owe largely to Professor Semper, 

 wdio states that the butterfly was first seen in 1863 by Captain Rachan, 

 one of numerous collectors of the Museum Godefroy, on the islands of the 

 Tonga or Friendly group, again nearly another 2000 miles from Ponape. 

 The first specimen actually obtained was secured in 1866 on Niuafau, one 

 of the islands of this group, and in the same year larvae were discovered 

 on Asclepias curassavica, a plant now spread quite as far as the Anosia. 

 We now begin to be able to record in part the rapidity of its spread ; for 

 it was first seen in Tutuilla, one of the islands of the neighboring Samoan 

 group, in 1867, but upon Upolu and Savaii, islands of the same Samoan 



