female would alight by placing her front legs across a horizontal grass blade, her head resting against the blade so as to brace the body in position. Here she would continue to hold the male beneath her for a little time, until the process was finished. The male, meanwhile, would be rolling the balloon about in a variety of positions, juggling with it, one might almost say. After the male and female parted company, the male immediately dropped the balloon upon the ground, and it was greedily seized by ants. No illustration could properly show the beauty of the balloon." (Aldrich and Turley, "A Balloon-making Fly," _American Naturalist_, October, 1899.) "In many species of moths the males 'assemble' around the freshly emerged female, but no special advantage appears to attend on early arrival. The female sits apparently motionless, while the little crowd of suitors buzz around her for several minutes. Suddenly, and, as far as one can see, without any sign from the female, one of the males pairs with her and all the others immediately disappear. In these cases the males do not fight or struggle in any way, and as one watches the ceremony the wonder arises as to how the moment is determined, and why the pairing did not take place before. Proximity does not decide the point, for long beforehand the males often alight close to the female and brush against her with fluttering wings. I have watched the process exactly as I have described it in a common Northern _Noctua_, the antler moth (_Charæax graminis_), and I have seen the same thing among beetles." (E.B. Poulton, _The Colors of Animals_, 1890, p. 391.) This author mentions that among some butterflies the females take the active part. The example here quoted of courtship among moths illustrates how phenomena which are with difficulty explicable by the theory of sexual selection in its original form become at once intelligible when we realize the importance of tumescence in courtship.