XLVI 



the general colour" in individuals of Iphias (Hebomoia) GLAUcrppE Bsd., occur- 

 ring in some regions, as referred to on page 35 of my treatise o^i the Java 

 Pieridae, is particularly adapted to afford an insight into this process of change 

 and the origin of the colour markings on the wings of Rhopalocera. 



I have referred above to the broad transverse band which in many Rhopa- 

 locera devides the upper side of the fore-wings into two parts. Such bands 

 occur, as I have already noted when treating of the Hesperidae, in many Rhopa- 

 locera, among Satyridae in Neorina and especially in various species of Debis, 

 sometimes in both sexes, at other times only in the 9. this band having some- 

 times resolved itself into dots or stripes, the one and the other clearly indic- 

 ating various stages in a process of development whose nature, however, is 

 not clear. In the instance referred to of the butterflies of Cyllo it is, never- 

 theless, clear that we are concerned with a phenomenon of colour evolution 

 and it is, therefore, probable that these bands in other Rhopalocera must be 

 interpreted in the same way. How does this process operate, however, in this 

 instance? Why is it that with the spreading of the black pigment in Cyllo 

 butterflies just this band has remained intact so long? One would be inclined 

 to assume that this spreading took place from both extremities towards the 

 middle; such a spreading of the black pigment from the apex towards the 

 base occurs indeed in the 9 of Thyca Belisama Cram., but in Hebomoias and 

 other Pieridae the original colour, on the other hand, is clearly driven towards 

 the apex. As a rule the band in question is white or at least of a very light 

 colour and therefore indicates the occupation of a region where the original 

 colour has remainnd exempt from the invasion of black and has gradually 

 faded. But all this does not make it clear to me why this has occured in 

 these instances. 



For an explanation of the origin of the so-called eye-spots, a phenomenon 

 also of frequent occurrence in Satyridae, a knowledge of colour evolution is 

 likewise requisite ; this phenomenon, and therefore everything related to it, may 

 better be discussed in connection with the erroneous conceptions concerning the 

 so-called seasonal varieties. 



To this I will, therefore, now proceed. On pages XIV to XIX of the intro- 

 duction to my treatise of the Pieridae of Java I have already declared myself 

 to be opposed to the prevalent misconception concerning the dry and wet-seasonal 

 forms; this is more especially conspicuous with reference to the Satyridae. 

 Following in the footsteps of de Niceville, Moore in his Lepidoptcra indica has 

 adopted a number of well separated forms of the dry and the wet season and 

 among these the Satyridae play an important role ; others again have followed 



