86 AMERICAN SPIDERS 



The most important difference in the sexes is the greater 

 thickening 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 abdo- 

 men, 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. 14 



The little male of Habrocestum pulex is not so gaily colored as 

 some of his relatives, but he makes up in enthusiasm for his lack of 

 brilliance. His whirling dance has been excellently described by 

 the Peckhams: 



He saw her as she stood perfectly still, twelve inches away; 

 the glance seemed to excite him and he at once moved toward 

 her; when some four inches from her he stood still and then be- 

 gan the most remarkable performances that an amorous male 

 could offer to an admiring female. She eyes him eagerly, chang- 

 ing her position from time to time so that he might be always in 

 view. He, raising his whole body on one side by straightening 

 out the legs, and lowering it on the other by folding the first 

 two pairs of legs up and under, leaned so far over as to be in 

 danger of losing his balance, which he only maintained by sid- 

 ling rapidly toward the lowered side. The palpus, too, on this 

 side was turned back to correspond to the direction of the legs 

 nearest it. He moved in a semicircle for about two inches and 

 then instantly reversed the position of the legs and circled in 

 the opposite direction, gradually approaching nearer and nearer 

 to the female. Now she dashes toward him, while he, raising his 

 first pair of legs, extends them upward and forward as if to 

 hold her off, but withal slowly retreats. Again and again he 

 circles from side to side, she gazing toward him in a softer mood, 

 "Ibid., p. 43. 



