vnr 



the surface of the wings, in some cases, as in D. Chrysippus L., to a very 

 limited extent but much more in others, such as D. Genutia Cram., following 

 espially the veins but leaving between them larger or smaller patches of 

 the original colour in which the fading process in continued. In the latter 

 species and some others it has become a bright orange and in others again 

 it becomes lighter in shade, as, for instance, in the Javanese D. Melanippus 

 Cram., while in a form of this species occurring elsewhere, distinguished 

 by the name Hegesippus Cram., this orange has become entirely white in the 

 hind wings. 



In a great number of species, of which Danais Juventa Cram, may be 

 taken as the best known example, the original colour has changed completely 

 into white which re-appcars everywhere in peculiar streaks and spots through 

 the black, mostly faded to brown ; reaching the same goal, in fact, by another 

 road, as effected in Euploeas by the increase of white. In some species 

 remnants of the original red or its fading into yellow have been retained by 

 different methods, such as D. Tytia Gray and D. Aspasia F., the latter also 

 in Ideopsis Chloris Feld. where the black has again been diffused in another 

 manner as is also the case in Hestia, unless the colour pattern of Hesxia 

 is to be regarded as consisting of the remnants of the much diffused black 

 reduced for the greater part by the fading process, which is quite po.ssible. 

 The unusual size of the butterflies of this genus, indeed, justifies the assumption 

 that a very ancient form has been preserved in them ; they stand in the same 

 relation to the other Danaidae as ORNiXHOKrERA to the other Papilios and as 

 regards the last named it appears from the history of the development of the 

 larvae, as will be indicated when discussing P. Memxon L., that they have 

 originated from more ancient forms agreeing with the present day Ornithoptera. 

 The exceptional size of the Saturnias also supports this view, the grounds 

 for which, however, cannot for the present be discussed. Not only in mammals, 

 birds, and reptiles giant forms have existed in former periods of which only a 

 few relics have been preserved ; in insects this was also the case and the large 

 forms of Lepidoptera, now extant and constantly decreasing in size, must 

 similarly be regarded as such relics. In D. Chrysippus L. a species in which 

 the diffusion of black has been kept within narrow limits, the colour in several 

 individuals living sometimes, but not invariably, in different districts, exhibits 

 fading which now and again has become partially white and has thus produced 

 the imaginary species Dorippus, Alcippus, and Alcippoides. 



How is it to explained that the process of colour evolution operates in such 

 different ways ? 



In the first place it should be observed that however much variety may 



