16 L. cle Niceville — Butterflies of the subgenus Tronga. [Ko. 1, 



Certainly no such seasonal forms are found in the genus Euploea occur- 

 ring in those regions. 



I have long lield the opinion, gained by an extensive knowledge of 

 the genus Euplcea in life, that in nearly all cases it is highly improbable 

 that any one spot will contain two really distinct species of one group 

 of the genus. Dr. Moore in his most valuable monograph of the genus 

 Euploea written in 1883 evidently had no such suspicion, never having 

 seen a live Euploea, nor an opportunity of examining hundreds of speci- 

 mens from a single locality as I have frequently done, as, for instance, 

 he gave six (one with a query) species of Tronga from Borneo ; six of 

 Pa6?emma from Assam, and probably several others, as he records four 

 other species from E. and N.-E. Bengal, and another with a query, which 

 probably mean Assam; four of Isamia from South China and three from 

 Cochin China ; and four of Stictoploea from Assam. While working up the 

 Bornean Trongas, I thought it would be well to verify as far as I could this 

 general opinion of mine that it is exceptional for two distinct species 

 of one group to really occur in any one given locality, and taking up only 

 India and those regions lying adjacent thereto and Southern China, 

 regions that I am more or less well acquainted with from visiting many 

 of them for the purpose of collecting butterflies, I find on the whole 

 that my conjectures are likely to prove correct, though in two or three 

 groups, subgenera or genera (it is immaterial for our purpose how we 

 terra them, though I prefer subgenera in our present ignorance of the 

 transformations of most of the species), this is certainly not the case, 

 as in Penoa we have a brilliantly blue-glossed species {deione, Westwood) 

 and a non-blue-glossed species {douhledayl, Felder) occurring together 

 in Sikkim, Assam and Burma ; while two quite distinct non-glossed 

 species, differing entirely in size and male sexual brands, gardhieri, 

 Fruhstorfer, and menetriesiij Felder {=piniuilli, Butler and evalida^ 

 Swinhoe) occur together in the Malayan Peninsula and Sumatra; again 

 in Fademma we have in the region of Calcutta and southwards to Tra- 

 vancore a species (hollari, Felder) which is but slightly if at all blue- 

 glossed in those regions, gradually merging in other parts of Bengal 

 (tlie Maldah district for instance), Sikkim, Bhutan and Assam into a 

 strongly blue-glossed species {Mugii, Moore). It is diflBcult to know 

 how to deal in systematic work with such forms, as the one is quite 

 distinct and constant in one region, while in another region this erst- 

 while "good species" becomes gradually merged into another species 

 which in its extremest form is absolutely different. In Hongkong also 

 two apparently quite distinct species of Crastia occur, viz., godartii, 

 Lucas, and 7mi6erg'^, Wallengren. However, these exceptional groups do 

 not greatly invalidate my previous conceptions of these various subgenera 



