( xliii ) 



head of the male was close to, and generally over the anal 

 angle of one hind-wing of the female. So far as it was 

 possible to follow them with the eye during their flight, the 

 same relative position was maintained, the male following so 

 closely that his head was probably often in contact with the 

 hind-wing of the female. They alighted two or three times in 

 the positions I have described, but were probably disturbed 

 by my attempts to approach them. In a few minutes, how- 

 ever, they came to rest, and remained for about twenty 

 minutes, during which I was able to observe them closely at a 

 distance of about three feet. The male appeared to show 

 excitement, especially in the earlier part of this period, in 

 the frequent quivering of his wings, and occasionally in the 

 much slower scratching movements of his second pair of legs. 

 As far as I could see, these movements were not felt by the 

 female and did not affect her. Of far greater interest was 

 the movement of the head and antennse, which evidently 

 perform an epigamic function of considerable importance in 

 this species. From the previous description of the relative 

 positions it is clear that the antennre as well as the head of the 

 male overhang the hind-wings of the female. During the 

 earlier part of this period the male's head was jerked 

 repeatedly up and down, the knobs of the antennae being of 

 course moved through a large arc. At the same time I heard 

 a succession of clicks distinctly synchronous with the jerks 

 and evidently due to them. I have no doubt that the clicks 

 were caused by the rapping of the male's head or the knobs of 

 his antennjB upon the hind-wing of the female. The move- 

 ments were extremely rapid and were many times repeated. 

 The female remained apparently passive throughout the 

 period, but three times she shut her wings up with a snap and 

 remained in this attitude foi- a few seconds. At other times 

 her wings were spread out flat, the anterior pair not being 

 directed sufficiently far forward to bring their costal margins 

 quite into line. The position of the wings of the male was 

 not equally uniform, but they were always more or less out- 

 spread even Avhen made to quiver. After about five minutes 

 from the beginning of this long period the signs of excitement 

 became much less marked, while the rapping movements only 



