373 



as the latter originall\' showing a continuous distribution of 

 coloured matter over the whole extension of the structural 

 elements they belong to, but secondarily being frequently broken 

 up into isolated patches of darker-coloured matter scattered 

 over a lighter held. The internervural dark patches are by 

 preference located both along the outer margin of the wing 

 and near the line of origin of the marginal nervures from the 

 discoidal vein. Besides these patches of dark pigment one or 

 two transverse rows of light spots may occur on the wings. 



A third method of comparative morphology may also be 

 followed : the investii^ation of the full-grown forms, with all 

 their modifications by sexes, varieties, geographical races, 

 aberrations, sexual and seasonal polymorphism, and, lastly, the 

 examination of artificially produced deviations from the normal 

 type. It is obvious that I must restrict myself to a few remarks 

 on some of these topics, each of which contains full material 

 for an extensive communication. 



First of all I should wish to direct your attention to the 

 fact that instances of wing-patterns more or less harmonising 

 with the above-sketched primordial plan occur in all families 

 of diurnal butterflies, and that among their bearers many forms 

 are found which for dift'erent reasons may be considered as 

 primitive. 



One of the finest examples is Hcstici (figs. 14 and 14^0. among 

 the Danaids. In this genus almost all the features which may 

 be regarded as characteristic of phylogeneticahy ancient forms 

 show themselves in a striking way : simplicity of pattern and 

 colours; restriction of the pigment-accumulations to the nervures 

 and their intervals ; concentration of the dark pigment into 

 regularly arranged series of spots ; accentuation of obhterated 

 nervures by pigment-stripes, equality of fore- and hindwings and 

 of upper- and underside. 



These same conditions are almost as fully realised in the 

 wing-pattern of the very interesting Papilio zahnoxis (fig. 15), 

 which for various other reasons is regarded by competent ento- 

 mologists as a relict from former periods of butterfly-existence, 

 and likewise, though to a much less extent, in another aberrant 

 member of that family: Papilio or Drurxia (iii/iiiuulii<s. 



From zalmuxis our attentiiui is logicall}' directed to Chifi- 



