( 93 ) 



VIII. The Geographical Distribution of Danais Ar- 

 chippus. By W. L. Distant. 



[Read 7th March, 1877.] 



With the exception of Pijravieis Cordui, Danais ArcJiip- 

 jms seems soon likely to become the most cosmopolitan of 

 butterflies. It occurs in the New World from Canada to 

 Bolivia and has spread over some of the islands of the 

 Pacific to Queensland and New Guinea. But the great 

 interest which attaches to this insect is, that its dispersion 

 is now taking place over wide areas, almost, we may say, 

 before our eyes; and thus we may not only, by the strict 

 logic of analogy, understand some of the processes by Avhich 

 other butterflies have acquired a wide distribution, but 

 also in this case have an opportunity of Avatching for local 

 modifications of form and colour, without the species proves 

 to have a more rigid adherence to original type under 

 different conditions than seems to have been the case with 

 other species of the genus. Species to which it is con- 

 colorous, as Plexippus, CJirjjsipjnis and Gilippus, have 

 allied to them a number of forms, which, though locally 

 constant, are called by some Entomologists species, and by 

 others considered only as varieties, whilst amongst other 

 species of the genus Avhich are associated by a different 

 shade of coloration the same thing equally applies to a 

 number of distinct and equally constant local forms or 

 species approximating more or less to Aglea and Limniace. 

 Its sudden appearance in Queensland for the first time 

 and in large numbers was recorded by Mr. Miskin a few 

 years ago,* and we can now also add it to our own fauna, 

 two specimens on good authority having been taken in this 

 coimtry in the autumn of last year — the fii'st on the 

 6th September, at Neath, S. AVales,f the second at Hay- 

 ward's Heath on the 17th October,:!: and as we can scarcely 

 believe that English Entomologists are perfectly ubiquitous 



* Ent. Mo. Map;, vol. viii. p. 17, 1871. 

 + Ih. vol. xiii. p. 107. 



X Entonioldfjist, vol. ix. p. 26.5. Since this was written a third cxnniplc 

 has been recorded as taken in Sussex in September hist. 



TRANS. ENT. POC. 1S77. TAUT II. C.TL'Ni:.) 



