XX vr 



And while the upperside of the 9 of Sithon Nedymond Cram, is, as 

 already said, the same in colour as e. g. that of the $ of Neocherita Manda- 

 RiNUS, Hew. (PI. XXVI, 156) its underside resembles that of many species 

 which have there a great deal of orange, but not that of the just mentioned 

 NEOCHERrrA, which in its turn has a range of colours very closely allied to 

 those of the cf of Sithon Nedymond Cram, the upperside of which coincides 

 more nearly with the cT of Deudorix Sphinx F. (PI. XXV, 129a); more cases 

 of the same kind could be quoted. 



All this certainly makes the impression of great confusion. Yet through 

 it all we have repeatedly met with phenomena which seem to indicate a definite 

 tendency in the process of colour-evolution, a leading purpose, so to speak. 

 The characteristic stripes upon the underside of many Lycaenae, the peculiar 

 spots in the same place in the Arhopala species can only be understood in that 

 way ; they appear too frequently to permit us to doubt of their being the expression 

 of a normal process which, under normal circumstances, will always manifest itself in 

 the same way, and only in abnormal circumstances will be expressed in a different 

 way, that is, when disturbances of whatever sort they may be, exercise an 

 influence upon the normal course of the changing process. For here also, the 

 same thing is true, as we have already said about the circular spots ; a repeated 

 recurrence of the same form points to the same cause, and, therefore, the 

 normal course of the process will always bring about the same phenomena while 

 deviations from it caused by various disturbing influences will appear in all 

 manner of ways in the phenomena, which are caused by the process. 



The way in which the gradual disappearance of the darkening process 

 can be followed in many Lycaenae, as already described, plainly shows that 

 this process runs a regular course, not governed by caprice, but one which 

 develops unequally in the different species and sexes, although always tending 

 in the same direction. If we return to the above mentioned group of the 

 Gerydinae we find there such a remarkable example of the regularity with 

 which the evolutionary process of darkening develops, as removes all possibility 

 of doubt that it proceeds in a definite direction as if governed by a steady 

 plan. I have mentioned it in the text, but I think advisable to quote it 

 rather extensively here, that in Miletus Symethus Cram. (PL XIX, 8d) the 

 darkening of the cf proceeds in such a way, that the white spot on the upper- 

 side of the primaries, which is still fairly large in the $, is gradually com- 

 pressed into an insignificant relic. The cf which are least advanced in this 

 evolutionary process, do not differ much from the $ with respect to this white: 

 this is the form which I have marked as B (Plate XIX, 8;^) ; in those cf from 



