No. 519] THE COURTSHIP OF ABANEADS 175 



sedentary existence, or makes excursions mainly for food, 

 the male in many species becomes a wanderer when he is 

 adult, searching for a mate. The male thus comes to 

 spin less and to run more; and a morphological conse- 

 quence of this habit is seen in the total or nearly complete 

 loss of the cribellum, or spinning plate, by adult males 

 of certain species. It is possible his relatively greater leg 

 length may be in some cases also associated with this 

 habit. These few cases would fall in line with the theory 

 of Cunningham ( 11)00), being characters due to difference 

 in mode of life of the sexes. But all such phenomena 

 would be likewise regulated by natural selection. 



6. The secondary sexual characters which operate to 

 protect a particular sex in the struggle for existence are 

 found mostly in the females, and these would be subserv- 

 ient to natural selection. In certain spiders, as notably 

 some epeirids (Arr/iopc, Acrosoma, (iastcracantha), the 

 female is not only much larger than the male, but also much 

 more brightly colored, often with most conspicuous black 

 and yellow or red and yellow markings ; and in Acrosoma 

 and Gasteracantha the abdomen may be drawn out into 

 angular processes and spines. We can not accept for this 

 case the Peckhams' suggestion that this is due to differ- 

 ence of mode of life of the sexes, for so far as is known 

 the males of these have the same mode of life as those of 

 other epeirids. These brilliant and remarkable females 

 all build their snares in the open sunshine, and remain 

 upon the centers of the snares. They would seem rather 

 to represent cases of warning coloration, this ultimately 

 protective to the possessors: in Acrosoma and Gasterar 

 cantha the bright markings would serve to advertise the 

 hard and spinous abdomina, and in Argiope, which is 

 soft-bellied, perhaps to announce the large snare. Pos- 

 sibly the brushes of hairs on the legs of another female 

 epeirid, Nephila, would be an example of warning char- 

 acters calling attention to the unusually large and power- 

 ful web, thus protecting the snare against birds. It is 

 always difficult to be sure of a correct interpretation of 

 phenomena of this kind, but it would seem probable 



