HEREDITY IN LEPIDOPTERA. 195 



numerous species of Lepidoptera have caused the development 

 of some remarkable phases of variation. By closely observing 

 these phenomena for many years, it has of late thrown much 

 light on the origin and development of several of our local 

 species and varieties. Mr. Tutt, in his papers on Melanism, 

 etc., has dwelt at length on the effects of certain localities in 

 darkening British Lepidoptera, but, so far, that gentleman's 

 efforts have been directed towards an explanation of the causes 

 producing melanism only. When we study the subject in the 

 opposite direction, we just as easily reach conclusions (in their 

 bearing as the case may be) in the development of brighter 

 and paler colours. The sub-family Satyrince comprise the 

 blackest species of known Rhopalocera. They also constitute 

 the second group in Bates' Structural Classification of Butterflies, 

 and considering the colours and low structure of the group, 

 they were, doubtless, among the first to appear in early geolo- 

 gical times. I am inclined to regard black as the primary 

 colour of Lepidoptera, and the one most suited to the cool, 

 wet climates of the ages through which they have passed. 

 The evolution of the numerous species constituting the group, 

 or of the higher groups from the Satyrince, need not be dis- 

 cussed here ; we have sufficient evidence of their great 

 antiquity and of several species still retaining their primary 

 colour from their zone of origin through geological time ; it is, 

 therefore, not difficult to understand how, under the ever- 

 changing conditions and rapid modification of climates in 

 modern times, numerous species should develop a tendency to 

 vary in a given direction. The hereditary tendency to vary is 

 more strongly marked in some groups than others, but I agree 

 with Mr. Tutt in laying stress on this as an important factor in 

 the production (under certain conditions) of Melanism, and it 

 seems to me that we must take a much wider grasp of the 

 subject than we have been accustomed to do when dealing 

 with these important problems. The law of heredity among 

 insects is comparatively unknown to entomologists, and until 

 the science is perfectly studied very little sound progress will 

 be made in developing our knowledge of the laws of variation. 



The thought has frequently occurred to me that the peculiar 

 and beautiful variation of certain groups or species operates 

 more from within than without. It seems to me not to be the 

 mere external influences of artificial environment that produce 

 the variation (useful or otherwise) in a bred species, but to be 

 due to the law of heredity operating in a given direction. It 



