OBSERVATIONS ON SEXUAL SELECTION IN SPIDERS 

 OF THE FAMILY ATTIDiE. 



GEORGE W. AND ELIZABETH G. PECKHAM. 



Introduction. 



Mr. Wallace, in his well known essay on Colors of Animah, 

 remarks that color per se may be considered normal and needs 

 no special accounting for; that amid the constant variations 

 of animals and plants color is ever tending to vary and to 

 appear where it is absent ; and that natural selection is con- 

 stantly eliminating such tints as are injurious to the species 

 while it preserves and intensifies such as are useful ; and in 

 opposition to Darwin he has argued that the sexual diversity of 

 color, common in many animals, has its primary cause in the 

 special need of protection for the female, which represses in 

 her the bright colors that are normally produced in both sexes 

 by general laws. Or, to put it in another way, he starts with 

 the fact of the variability of color in animals of both sexes 

 and says that in the female, where greater protection is needed, 

 the color is toned down or eliminated, while in the male, the 

 need for protection being less, the color may be preserved and 

 intensified. Mr. Wallace has supplemented this theory by 

 another factor ; he now holds that the frequent superiority, to 

 use his own words, of the male bird or insect in brightness or 

 intensity of color, even where the general coloration is the 

 same in both sexes, is primarily " due to the greater vigor and 

 activity and the higher vitality of the male. * * * This 

 intensity of coloration becomes most developed in the male dur- 

 ing the breeding season when the vitality is at a maximum. 

 * * * The greater intensity of colors in the male, which 

 may be termed the normal sexual difference, would be further 

 developed by the combats of the males for the possession of the 



