XX 



Felder there is a fine white line along the inner edge, where the vertical stripes 

 meet it ; in L. Celeno Cram this stripe is distinctly broader and the vertical stripes 

 at their lower end near this line are more or less, sometimes conspicuously, 

 broadened ; finally in L. Alexis Stoll, not only is the ground colour of the 

 primaries on the underside, as we have said, more whitish, but the white of 

 the stripes has often spread so much (see the picture of the female in Plate 

 XX, 3 7(^ especially) that it has often partially covered the markings and made 

 them indistinct. 



Taking all this together, we can see that each of these forms merely 

 represents a different stage in the course of the process of evolutionary fading ; 

 the replacing of the original colour by white is least in L. Cleodus Felder, 

 in L. Celeno Cram it is somewhat further advanced, and in L. Alexis Stoll. 

 it has gone furthest ; which can be seen most clearly on the underside, but 

 is also manifested on the upperside, where the most blue is found in the 

 first mentioned butterfly, while it has almost disappeared in both the others. 



This differentiation is therefore of so little importance that in my opinion 

 the three forms may be regarded as three races of the same species, which 

 should bear the name of the oldest one L. Celeno Cram, that is, if further 

 cultivation shall confirm, that Cleodus Felder and Alexis Stoll. reproduce 

 themselves as such, which is not certain yet. Each of these forms will finally, 

 when the colour-evolution has proceeded so far as to make it quite white, 

 have become the same as the others, so as to loose its individuality ; unless 

 in the mean time, in one of them, another differentiation has arisen which 

 would make a separate species of it. Other so called species of Lycaenidae 

 also I believe a knowledge of colour- evolution will enable us to reduce to 

 subsidiary forms of one species. 



A well kwown group of these Lycaenae, that which is often distinguished 

 as Cyaniris, forms a very good example of this fading process, and the very 

 uneven manner in which it proceeds. All the species included in it apparently 

 are derived from one stock form and are passing through the same process 

 of colour-evolution, which causes the colour which was peculiar to the original 

 stock to fade to white; a process in which the females are much further 

 advanced than the males, and in which therefore, female preponderance reigns. 

 But the process runs its course independently not only in each species, but 

 even in both sexes of the same species and in individuals of each sex, while 

 in one species transformation to a more advanced stage of colour change 

 takes place much earlier than in another. So that in the same species there 

 arises a difference in colour between the sexes, and even between individuals 

 of either sex. As, however, the process of change is the same in all the 



