( xxxiv ) 



the wing-surface, perhaps some other common tropical 

 Cryptogam. 



Dr. Karl Jordan communicateil the following note upon 

 the Variability of the Genitalia in Lepidoptera : — 



" For a long time it was the opinion of systematists that 

 the organs of copulation in insects were practically constant 

 within a species, and that therefore a form of insect which 

 was found to be different in these organs was a distinct 

 species. I demonstrated about ten years ago with Lepido- 

 ptera, and have since done so on several occasions, that there 

 is a certain amount of individual variability, and that this 

 variability in the organs of copulation is independent of the 

 variability in other organs, for instance in the wings. Indi- 

 viduals which are aberrant in pattern are normal in the 

 copulatory organs, and specimens with marked deviation from 

 the typical in these organs have normal wing-patterns. 

 Dimorphism in the wings, so strongly marked in many 

 Lepidoptera, is not accompanied by differences in the organs 

 of copulation. 



" On the other hand, I have found that there is often a more 

 or less marked geographical vai'iability in the organs of 

 copulation accompanying variability in the wings, a geo- 

 graphical variety of a butterfly or moth being in most cases 

 characterised by some distinction in the wing and the organs 

 of copulation. The bearing, on the evolution of species, of 

 this contrast of geographical and non-geographical variation 

 is obvious. It appears to me easy to understand why the 

 specimens of the same locality, which copulate together, are 

 on the whole the same in the organs of copulation, but it is 

 more difficult in the case of seasonal varieties. If the causes 

 of seasonal variation have anything to do with the origin of 

 new species, one should expect that seasonal forms, which are 

 often so very different from one another in the wings, were 

 also different in the organs of copulation. I have examined 

 many seasonally dimorphic species without result. Lately, 

 however, I have come across a solitary instance of seasonal 

 variability in the organs of copulation. The spring form of 

 Papilio xuthus is slightly but distinctly and almost constantly 

 different from the summer form in the "harpe" of the 



