xliii] ¢ 5 } 
positions were maintained, both insects resting with outspread 
wings, the female immediately in front of the male. The 
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 antennz, 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 antennz 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 antenne being of 
course moved through a large are. 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 antennz 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 for 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 when made to quiver. After about five minutes 
