258 PIEBID^E. 



specimens of T. hecabe, not only by the additional spot in the 

 discoidal cell on the underside of the fore wing, but by the 

 much larger, outwardly diffuse, reddish-brown apical patch on 

 the same wing ; but tie most careful and repeated examinations 

 of long series have shown me that Capt. Watson was right 

 in stating that the only constant difference between wet-season 

 specimens of T. hecabe and T. silhetana is the presence in the 



latter of the additional spot 

 in the discoidal cell of the fore 

 wing, as noted in the key. 

 With regard to the varieties 

 as I deem them of this form, 

 fig. 66 represents the upper- 

 sides (a) of var. heliophila, 

 Butler, and (6) of var. unifor- 

 mis, Moore. 



Larva. " In describing the 



Fig. 68.-2WM silhetana, varieties. j, arva f T ' hecabe ' L^n in our 



a. T. silhetana, var. heliophila. former paper, we said that we 



b. T. silhetana, var. uniformis. had got fourteen black pupffi 



all on one dry twig, and so 



close to each other that they almost touched. We did not 

 distinguish the butterflies which emerged from T. hecabe ; indeed 

 until the publication of Captain E. Y. Watson's very valuable 

 paper on the synonyms of some species of Indian Pierince in 

 vol. viii. of this Journal, p. 489 (1894), we made no attempt to 

 sort our specimens under the multitude of names with which 

 Messrs. Butler, Moore and Swinhoe have enriched the genus. 

 We have since discovered, however, that these black pupae are 

 not to be found on the ordinary food-plants of T. hecabe, but on 

 Wagatea spicata, and that they result from a gregarious larva with 

 a black head. This leaves no doubt that they belong to a distinct 

 species, and, having compared the butterflies which emerged from 

 a large number of both kinds, we find that those produced from 

 the black-headed larva and the black pupa bear the three dark 

 streaks and spots in the cell, in addition to the renif orm spot on the 

 discocellular nervules on the underside of the fore wing, by which 

 Captain Watson separates T. silhetana from T. hecabe. We have 

 figured the larva and pupa on plate vi, fig. 6, larva ; 6 a, pupa" 

 (Davidson, Bell &f Aitken.) 



The figures iu the plate represent a slender cylindrical green 

 larva with a conspicuous black head and a yellow ill-defined lateral 

 stripe, and a pupa in shape exactly like that of T. hecabe but 

 entirely brownish black in colour. 



The form next described Captain Watson considered the wet- 

 season form of silhetana, but though like silhetana it has three 

 spots or markings in the discoidal cell on the underside of the 

 fore wing, the shape of the wings and the general facies of 

 the insect seem distinct ; besides, so far as I know, it has only 

 been taken in the Nicobors. I have, therefore, provisionally kept 

 it separate. 



