No. 1.] SEXUAL SELECTION IN SPIDERS. 43 



reception of his attentions, advanced even nearer, when she 

 seized him and seemed to hold him by the head for a minute — 

 he strugghng. At last he freed himself and ran away. This 

 same male, after a time courted her successfully. 



SYNAGELES PICATA. 



These are small ant-like spiders. The most important sexual 

 difference, is the greater thickness of the first legs of the male. 

 These are flattened on the anterior surface and are of a brightly 

 iridescent steel-blue color. Unlike most of the Attid males this 

 species keeps all his feet on the ground during his courtship: 

 raising himself on the tips of the posterior six he slightly 

 inclines his head downward by bending his front legs, their 

 convex surface being always turned forward. His abdomen 

 is lifted vertically so that it is at a right angle to the plane of the 

 cephalothorax. In this position he sways from side to side. 

 After a moment he drops the abdomen, runs a few steps nearer 

 the female, and then tips his body and begins to sway again. 

 Now he runs in one direction, now in another, pausing every 

 few moments to rock from side to side and to bend his brilliant 

 legs so that she may look full at them. We were much im- 

 pressed by the fact that the attitudes taken by the males served 

 perfectly to show off their fine points to the female. We had 

 never known the male of this species until the day that we 

 caught this one and put him into the mating-box, and it was 

 while studying his courtship that we noticed how he differed 

 from the female in his iridescent first legs. He could not have 

 chosen a better position than the one he took to make a display. 

 We had six females in the box, and saw him mate with all of 

 them ; and each, after a time, made a cocoon containing three 

 large eggs. 



MARPTUSA FAMILIARIS. 



This is a ratJier plainly marked Aitus, well protected by its 

 coloring of gray and black, on the bark of trees and on fences, 

 where it is most frequently found. There is little difference 

 between the sexes. We placed the two together. She saw him 



