55 



very prominently spread and the colour of the under-side of the hind-wings 

 shines out at their upper-side. Ground colour white as in group sj or yellow. 

 Under-side dark yellow mixed with black scales, sometimes pale yellow, 

 quite plain, without remnants of spots or of the 8-shaped figure. Sometimes 

 also in much bleached specimens, white with a mother-of-pearl hue, as this is 

 also to be found in the next group. In that case, as a research in that respect, 

 made for me by dr. van der Weele, pointed out, a very far advanced stadium 

 in colour-evolution is reached ; that hue indeed is due to refraction and caused 

 by the fact that in the scales on the under-side the pigment is already absolutely 

 gone, even more so than I stated relative to the $ of Aporia Crataegi L. on 

 page IX of the Introduction. Batavia, Central Java, Borneo, Bawean, Flores, 

 Wetter. Of a specimen from the Rio-Lingga archipelago with small increase of the 

 black, the underside is brownish yellow with relic-pattern. (PI. IV, fig. i, c, e.). 



I. The same increase of the black much stronger, so that it extends, espe- 

 cially in specimens from North Celebes and Salaiara, nearly over the whole 

 upper-side of the wings. Ground colour yellow or white. 



Under-side plain yellow or white, often also more or less with a mother of 

 pearl hue. 



Not from Java, but from Great Sangir, Celebes, Salaiara, Ceram, Ternate, 

 Morty island, Waigiou, Banda, New Guinea, Timor. In Celebes, Great Sangir 

 and Salaiara this form occurs together with the group ^. (Bl. IV, fig. i, d./.). 



All the forms which have been mentioned here are united by all kinds 

 of transitions and occur at the same-time in the same flights, as has already 

 been said, as long as they are not confined to special regions, at least; the 

 oldest, the deep-yellow form Catilla Cram., however, only in a relatively small 

 number. By far the greater part of the specimens have already surpassed this 

 stage in the colour-evolution, some obdurate conservatives alone go on repre- 

 senting it. Just so all these forms appear from caterpillars which are bred at 

 the same time. So it is evident that these differences have very little to do 

 with the dry or the rainy season as I have stated on page XIX of the Introduc- 

 tion ; where such a thing is maintained, it is not founded on serious observation. 



I challenge anybody to explain in any other way than by my theory of 

 the colour-evolution all these different forms which occur in several islands beside 

 each other and which follow the same evolutional process; the way in which 

 they change and pass into one another, and the undeniable conformity which 

 such forms, though different, often show between themselves in the process of 

 their alteration. Assertions about external influences and suchlike things, give 



