xvn 



outer margin, already existed. This is so common in the 9, that, as already 

 said, it is frequently regarded as a female characteristic, although it is also 

 found amongst others in the above mentioned males of Lycaena Bochus Cram. 

 (PI. XXI, 48a) L. Marginata de Nic, (PI. XXII, 72a) and L. Ouadriplaga Sn. 

 (PL XXII, 73a). The simple fact is that in this darkening process a greater 

 susceptibility of the $ sex is revealed as preponderance, whereby it has proceeded 

 very generally in the $ as a rule, while so far only in a few species the cf has 

 changed in the same direction. By this means an accumulation of dark pigment 

 has formed, such as is mentioned on p. l in the introduction to my third 

 monograph. 



Upon the upperside of the cT which must also have been complete darkened, 

 but as a rule in a more even way, a structural colour must have established 

 itself, owing to the great susceptibility or predisposition for it in the Lycaenidae. 



Afterwards a retreating of the dark pigment may have begun, such as may 

 be as unmistakably recognised in Cyllo Leda L. (Plate XV, 3o/'.g.), this evolu- 

 tionary change having again proceeded further in the 9 than in the cf. The 

 consequence of this must have been, that the darkening in the 9 has again 

 vanished to a great extent, except in the accumulation at the apex, costal 

 margin and outer margin already referred to, which has given a more intense 

 character to it, forming what I have formerly called a "persistent spot;" for 

 the rest, in proportion as the darkening clears away, the underlying colour 

 appears again, having in the meantime faded very considerably. That the 

 original pigmental colour is not lost, even when an intense structural colour is 

 formed over it, is shown clearly by the vivid structural blue of the cT of Poritia 

 Erycinoides Felder (Plate XX, 2 3a. (5.); in fact, as this colour disappears in the 

 female, the red, in a faded condition, reappears again. In the faded colouring, 

 often a great deal of white is already seen, which increases during the further 

 progress of the change. In the cf", on the other hand, the uniform darkening 

 which is covered by a structural colour, seems often to have persisted, but not 

 seldom to be much diminished in intensity, which is shown, as I believe, in the 

 different and often much lighter shades which the structural colour assumes in 

 the various species which have reached different stages of this evolution ; where 

 there is still a thin layer of dark pigment, it becomes brownish, more or less 

 mixed with blue, and where the darkening has quite disappeared, the structural 

 colour, if it has been preserved, becomes a clear, sometimes even a very light 

 blue. This is why, where this kind of blue occurs, showing that the evolutionary 

 fading is already far advanced, the upperside of the underwings has often, 

 and the underside of both wings frequently become quite white. I consider 

 that the colour process in the above mentioned Lycaena Plinius F. could also 



3 



