xxirr 



nomenclature can be of some use ; but with much more moderation than is the 

 custom nowadays, if we do not want te exceed the limits of a really scienti- 

 fical study. In this way there never ought to be given a separate name to such 

 forms as only indicate evolutional changes of colour and no races ; in this case 

 they always ought to be distinctly indicated as forms, and it seems preferable 

 to me to distinguish them by numbers or Greek characters only, as I have 

 done with regard to Callidryas Pomona F. 



The following remarks are still necessary. 



The s)'stematic part of this work has been arranged by the well-known 

 Dutch lepidopterologist P. T. C. Snellen, who has indeed helped me greatly 

 with the rest also, by his knowledge of the Indo-Australian Lepidoptera, and 

 under whose supervision and for whose account a great part of the imagines 

 has been figured. I have only had part of them made, especially those which 

 must serve to make clear the process of the colour-evolution and also all the 

 numerous figures of the early stages which have been made in Java. European, 

 Eurasian, Javanese and Chinese draughtsman, the one more, the other less 

 capable, have been working at it under my supervision as the oppertunity 

 presented itself; those figures have always been compared by me with the living 

 animal. As to the imagines, these have been figured from dried specimens, 

 whose thorax and abdomen had often suffered by drying. This is an evil still 

 common to all figures of Lepidoptera and which I have not been able to avoid. 



The biological part is by me. Many important observations in this respect 

 have, however, kindly been given to me by Mr. Fruhstorfer, at present living 

 at Geneva, who certainly is one of the best connoisseurs of the Indo-Australian 

 Rhopalocera-fauna and who has also collected butterflies himself in Java. 

 Dr. VAN DER Weele, conservator at Leyden Museum was also so kind as 

 several times to assist me in some investigations. 



The scientific names of the plants which I got to know as the food of 

 caterpillars, I owe, so far as they are well-known plants or that I could 

 lay hold of the flowers, principally to the kind assistance of the well-known 

 botanist Prof Dr. Treub, who during the time I resided in Java, was Director 

 of the Government Botanical Gardens at Buitenzorg ; while also other botanists 

 there have sometimes been so kind as to determine the plants for me. For 



with — the difference is generally not excited b}- them, but by a dissimilarity in the process of 

 evolutional development caused by the separation, which is also why that difference is not 

 constant either, but the insects continue incessantly their evolutional change, as far, at least, as 

 they do not happen to be in a state of temporary epislasv. It is especially the phenomenon of 

 the colour-evolution which makes this clear to us. 



