58 PECKHAM. [Vol. 1. 



by touching with one leg a thread of her web ; the female 

 approaches him ; he flies, allowing himself to hang. Then he 

 rises, winding up the thread, when he is assured, by I know not 

 what movement, that he- will not be ill-received ; then he 

 approaches her and with one of the palpi touches her stomach 

 quickly many times. Then he returns, repeats the same act and 

 departs, if he succeeds in leaving. I say if he succeeds, because 

 I wish to relate what came under my observation in 1798. * * * 

 I put a male and female of the diadema spider together in a box 

 like a drum, closed with a veil at both ends. The male began 

 by making various movements, as if to draw the attention of 

 the female, who pretended not to perceive him, but only from 

 time to time touched some thread of the web. He boldly 

 approached, directing one of his palpi to her abdomen, and she 

 extending this toward the palp. * * * But I saw also with 

 surprise and indignation that, the work hardly finished, the male 

 not being able to fly on account of the confinement, the female 

 enveloped him in her thread, and having thus deprived him of 

 every means of defense, devoured him. Perhaps overpowering 

 hunger compelled her to it, but the act was very ferocious." 



SUMMARY AND CONCLUSION. 



In this paper we have considered the two theories by which 

 Mr. Wallace explains sexual color differences in animals — pri- 

 marily the greater vitality of the males, especially during the 

 breeding season, and secondarily the greater need of protective 

 coloring on the part of the females ; and we have found that 

 however satisfactory they may be where birds and butterflies 

 are concerned, they fail in each important particular when 

 applied to spiders. 



In our study of moulting habits we have seen that among 

 the Atlidx, where the sexual differences are strongest, males are 

 commonly more brilliant than the females; that the young 

 males nearly always resemble the adult females ; that the males, 

 when they differ from the females, depart from the general 

 coloring of the group ; and that when the females depart from 

 the coloring of the group they approach, in the same degree, 



