COLOUR IN LEPIDOPTERA. il 



and is accordingly to be considered as the younger colour, 

 does not seem to be quite a matter of course. 



The simple fact observed by Dr. Grafin von Linden that 

 in the ontogenesis of F. Machaon L. the early orange- 

 yellow spot on the hind wrings will turn to red afterwards, 

 is certainly not sufficient, where all similar observations 

 still remain so incertain to lead to such general deductions, 

 the more so as that spot later on turning to a dark red- 

 brown, betrays the interference of another dark pigment. 

 On the contrary it is quite sure that though these experi- 

 ments, testifying to a constant preoccupation with Dr. Eimer's 

 colour-pattern, are not all one might wish them to be re- 

 garding the observation of colour-evolution, they still give 

 the impression of the ontogenetical colour, specially of P. 

 Fodalirius L. presenting a remarkably stronger tint of yellow 

 than the actual colour of that butterfly shows now-a-days, 

 which seems conformable to a tendency to fading in colour. 



Neither can it be denied that where a little red pig- 

 ment is found in the oldest form next to a great deal 

 more of yellow pigment, the further ontogenetical course 

 does in no wise show a notable increase of the red colour, 

 as indeed it ought to if the yellow were slowly turning 

 into red. But there is more. As has clearly been demon- 

 strated by many experiments, also by those of Dr. v. Bem- 

 melen, the oldest ontogenetical state does not go further 

 back than to the relatively not very remote period in 

 which many of the now living, nearly related, species of 

 the same genus were differentiated from one another. Now 

 my supposition is that red was the general colour be- 

 fore the Pieridae, Papllionidae, Lycaenidae and Nymphalidae 

 were differentiated, that is in such a remote period that 

 those investigations cannot possibly recover anything thereof. 

 If then in the oldest investigable period some red pigment 

 is still always found, but ever lessening in the same measure 

 as the now living butterflies have become paler and more 

 distant from that original colour, this seems to me to be 

 wunderfully well in accord with my theory, indeed strongly 



Notes from the Leyden M^useum , Vol. XX.II. 



2* 



