350 Linnean Society. [Nov. 16, 



this character further carried out, and the wing appears to have a 

 subcostal nervure di\'iding into two nervules, and a median dividing 

 into four, so completely has the discoidal nervnire assumed the po- 

 sition of a branch of the latter nervure. The females of the genus 

 Sais have also this character, but in the males we find a still further 

 change of structure. In these the second subcostal ner\Tile assumes 

 the position of a fifth median nervule, and the subcostal nervure con- 

 sequently appears simple. 



Thus, leaving the genera Heliconia, Lycorea and their immediate 

 allies, which have the structure which is normal as regards the Di- 

 urnal Lepidoptera, though abnormal as regards the order, we find in 

 Ihina and some female Ithomi(S a structure nearly normal as regards 

 the whole order, but the males of the latter become abnormal in an 

 opposite manner to the prevalent character of the group ; next in 

 Mechanitis we find this structure common to both sexes ; and then 

 in Sais, the females retaining the same structure as in Mechanitis, 

 but the males varying still further from the type. 



This gradual change in the position of the discoidal nervure 

 actually occurring first in the two sexes of the same species, and 

 then becoming common to both sexes, is, in the opinion of the 

 writer, confirmatory in the highest degree of the theory laid down 

 by him in a former paper, as to the structure of the anterior wings 

 of the Diurnal Lepidoptera, and leaves, he thinks, no room to doubt 

 the correctness of the explanation there given of the apparent ano- 

 maly of those wings in the Papilionidee. 



In the sexual variations detailed above, it is the male insect which 

 varies most from the t^'pe, but the females of some species of Me- 

 chanitis present a remarkable structure in the anterior portion of the 

 wing, the costal nervure being united to the subcostal for the greater 

 part of its course. 



An additional interest attaches to these peculiarities of the wings, 

 from their being combined with the great peculiarities above referred 

 to in the structure of the anterior feet. 



The writer then proceeded to point out some analogies in the struc- 

 ture of the wings of the Ithomia and some Hymenoptera, especially 

 as regards the inner margin of the anterior wings and the anterior 

 margin of the posterior wings, and also with reference to a fringe of 

 hairs on the latter, analogous to the hooks occupying the same po- 

 sition in the Bees and other Hymenoptera. 



