355 



ON THE PHYLOGENETIC SIGNIFICANCE OF THE 

 WING-MARKINGS OF RHOPALOCERA. 



By J. F. VAN Bemmelex, Groningen. 



(Plates XXXII-XXXIV.) 



Introduction. 



Twenty-two years ago, at an assemblage of the Dutch Con- 

 gress for Science and Medicine, I read a paper on my investigations 

 into the development of the colour-pattern and the neuration 

 of the wing in the chrysalis of VanessidcB. These investigations 

 had led me to the following conclusions : 



The colour-pattern of the imaginai wing arises rather 

 suddenly during the last days of the pupal period. 



Notwithstanding this each colour needs a certain lapse of 

 time to reach its full intensity ; the whole aspect of the phe- 

 nomenon consequently reminds one of the gradual appearance 

 of a photograph in the developing-beith. 



The dift'erent colours do not appear simultaneously, black 

 coming some twenty- four hours after the others. Yet from 

 the moment of their first appearance they occupy the same 

 areas filled out by them in the full-grown pattern. 



Accordingly the parts destined to become black are left 

 blank during the foregoing development of red, yellow, or brown. 



Neither radiation from centre of first appearance nor tres- 

 passing of one colour on the dominion of a neighbouring one 

 occurs. 



But these rules only apply to the components of the definite 

 imaginai pattern. This pattern, however, is preceded by a very 

 different one, which arises soon after pupation, and remains 

 practically almost unchanged up to the sudden manifestation 

 of the imaginai one. We may call it the original or primitive 

 pattern. In Pyya))icis cardui it consists of a cinnamon-brown 



