310 THE PANORPOID COMPLEX, i., 



chance convergence, I shall hope to prove in detail later on, when 

 we come to consider the question of kirxal forms; the larva of 

 Enschr}}io)i being, in almost exery respect, that of a typical 

 Hesperiid. 



From the above evidence, the origin of the Amplexiform type 

 of wing-coupling in the Butterflies is naturally suggested as fol- 

 lows. The ancestors of the Butterflies must have had a wing- 

 coupling apparatus of the type seen in iSt/nrnuni at the present 

 day. By developing a manner of flight differing from that of 

 the moths, principally in the greater amplitude of wing-stroke 

 but lesser number of vibrations per second, the delicate, elong- 

 ated bristles of the frenulum in the female first began to fail to 

 hold the wings in position. The retinaculum being already too 

 far out for the shorter bristles to be of any use, the whole 

 frenular apparatus would then rapidly become aborted, and the 

 insect would depend upon the pressure exerted by the large 

 humeral lobe of the hindwing for keeping the wings in position. 

 That is to say, the Amplexiform type of wing-coupling first 

 became adopted in the female only, as we see it in Eui<che))Lon 

 at the present day. Next, considering the question of the male, 

 evolution could still proceed along one of two directions: either 

 the overfolding of the radius might continue to increase, until 

 an efficacious, hasp-shaped retinaculum (of the type seen in most 

 male f renate moths) had been developed, thus saxing the stronger 

 frenulum of this sex from extinction; or the line of evolution 

 might follow that of the female, presumably by the change in 

 the method of Might making it impossible for even this strong 

 frenulum to continue its hold upon the retinaculum, at a time 

 AS hen the latter had not yet i-eached the hasp-shaped stage. In 

 that case, frenulum and retinaculum would, in the end, become 

 aborted, as in the female, and we should arrive at the full Am- 

 plexiform type exhibited by the Buttertlies in both sexes. 



