344 



SEXUAL SELECTIOX. 



[I'aut II. 



wing which serves as the liddle itself. One of the ner- 

 vures (a) ou the under surface of the former is finely ser- 

 rated, aud is scraped across the prominent nervures on the 

 upper surface of the opposite or right wing. In our Brit- 

 isii FJcasfjonura viridisshna it appeared to me that the 

 serrated nervure is rubbed against the rounded hind 

 corner of the opposite wing, the edge of which is thick- 

 ened, colored brown, and very yharp. In the right wing, 

 but not in the left, there is a little plate, as transparent as 

 talc, surrounded by nervures, and called the speculum. 

 In Ephippiger vitium^ a member of this same family, we 

 have a curioiis subordinate modification ; for the wing- 

 covers are greatly reduced in size, but " the posterior part 

 of the pro-thorax is elevated into a kind of dome over the 



Fig. 12.— Chlorocaslus Tanana (from BatesV a. b. Lobes of opposite winjj-coveis. 



