SECONDARY SEXUAL CHARACTERS IN PAPILIONID^. 349 



carries the greatest weight, for when brought into competition 

 with the physical the latter has simply to succumb to it. It is 

 only when the former influence is exerted in a negative manner 

 that the effects arising from the physical conditions can survive. 

 We have thus sound reasons for supposing that the insects are 

 confined to particular zones principally by means of the organic 

 barriers which prevail upon either side of them. 



It may be true to a considerable extent that the physical 

 conditions operating upon the organism during the course of 

 many generations do produce effects and modify peculiarities 

 favourable to their survival, but only through natural selection, 

 for if these climatic modifications possessed traits or developed 

 correlative characters which were antagonistic to their well- 

 being, they could not possibly retain their place successfully in 

 the great struggle for existence. 



Birmingham, Oct. 20tb, 1896. 



THE ABERRATIONS OF SECONDARY SEXUAL 

 CHARACTERS IN PAPILIONIDiE. 



By John Watson. 



In the 'Entomologist,' vol. xxviii. p. 166 (1895), I drew 

 attention to two aberrations of secondary sexual characters in 

 male Rhopalocera, one being an androconia-bearing male of 

 Papilio parisy L. ; the other being a male of Eriocolias fieldii, 

 Men., without the characteristic congested scale-patch on hind 

 wings. 



A few weeks since, in going over the fine collection of my 

 friend Mr. Paul Schill, I came across another male of P. paris^ 

 identical in all respects to mine ; and later on again, in a small 

 collection I received from Shillong, in Assam, I found another 

 male with this character faintly showing, but at the same time 

 quite appreciable on examination with a lens, and thus being 

 intermediate between typical P. paris and the androconius aber- 

 ration. This brings forcibly to my mind the need for fixing an 

 identity to these phylogenetically valuable evidences of generic 

 and specific affinity. 



In regard to P. paris^ on microscopical examination of a 

 small portion of scales taken from the androconius nervule, it is 

 clearly seen how the long filamentous scales have been derived 

 from the ordinary dark brown dentate ones ; for I have on one 

 slide scales showing the whole range of variation from normal 

 scale to androconia. The plan of the development from the 

 ordinary squamose quadridentate scale appears to be this : — 

 Coincidental to the lengthening of the scale, usually (though not 



