44 



tration (PI. X\^ fig. 30 //, />). These stripes may even disappear entirely or 

 nearly so, although in that case more or less isolated spots of black pigment remain 

 (PI. XV, fig. 30rt') in a similar manner as is the case in Pieridae with the 

 brown spots, produced by the same process, on the under side in species of 

 Callidryas and Terias. {Pieridae, PI. Ill, fig. 6/, 6/, ^b, and PL IV,/ig. s**). 

 Frequently the diminution of black at that spot proceeds more evenly giving 

 rise to the kind of marking termed " /^iese/u/ig " by German Entomologists, where 

 the black pigment has been retained in so finely divided a condition reminding 

 one of the minute drops of water of a drizzle, a form of marking which is 

 also met with in many other butterflies, for instance on the under side of the 

 hind- wings in Iphias (Hebomoia) Glaucippe Bsd. 



If next the black pigment continues to diminish, the original colour no 

 longer covered and faded to yellow, now reappears, (PI. XV, fig. lOif^), so that 

 the individuals which are far advanced in this evolutionary process exhibit 

 yellow on the under side now blended with but little black, and in these the 

 upper side is faded to a light grey. (PI. XV, fig. 10/). 



The ocelli, which have been fully dealt with in the introduction, especially 

 deserve attention in this connection. Those most highly developed are 

 found in individuals whose under side has reached an advanced stage of 

 "drizzling", for the most part where the original colour universally reappears 

 as yellow. (PI. XV, fig. 10^,'). As a matter of fact all these forms of Cyllo 

 Leda L. can only be regarded as the same expression of excessive inequality 

 in the individual manifestion of the evolutionary processes of form and colour 

 which give rise to the polymorphism in many other butterflies but which in 

 C. Leda L. presents a greater amount of confusion. Thus, for instance, the 

 origin of the projecting appendages on the wings already referred to, and at 

 one time more pronounced than at others, is the same as that of the so-called 

 tails in the Achates form of Pap. Memnon L. Three circumstances co-operate 

 to make this less manifest in this case : 



1 ^. That in C. Leda L. the colour of the upper surface and that of the under 

 surface of the wing^s in each individual continues its evolutional modification 

 without, apparently, any inter-relation; in the cases of polymorphism, as in 

 Pap. Me.m.n'on L. or Callidryas Pomona L., this holds good likewise but by 

 no means so universally, since in most cases a definite pattern on the upper 

 side corresponds to a definite pattern on the under side. 



2" That, although in the two species mentioned, for instance, there can 

 be no (juestion of sexual polymorphism and this difference of form has nothing 

 to do with sex itself, this difference, nevertheless, manifests itself in the sexes 

 of these butterflies in various stages of development and thereby facilitates the 



