18 PECKHAM. [Vol. 1. 



young are not exactly like the adult female they resemble her 

 much more closely than they do the adult male. This is one of our 

 most beautiful males. The highly iridescent scales, which cover 

 the entire body, make it impossible to give, in a painting, a 

 correct idea of its brilliancy, since the color changes in every 

 light. The male only gets this gorgeous livery at the last moult, 

 just as he becomes mature, though in some species the nuptial 

 robe is acquired one moult before maturity. 



The family Attidse, from which these illustrations have 

 been taken, is by common consent, placed at the head of the 

 order, and contains among its 1,500 species the greatest amount 

 of sexual difference and the highest development of ornamen- 

 tation ; indeed, as Ave have seen, Wallace speaks of them as re- 

 sembling jewels rather than spiders, and Walckenaer says that 

 their species are well marked by the rich diversity of their 

 colors and the variety of the designs which ornament their 

 abdomens.^ 



In the seventy-eight species described in our work on the 

 Attidse of North America we have both male and female in 

 only forty ; or, to be more accurate, we have felt warranted in 

 placing males and females together in only forty instances. 

 Doubtless in many cases we have separated the two sexes, mak- 

 ing two species out of one, but the difference in color is so great 

 that, without knowledge of their habits, no other course was 

 possible.^ Of the forty species, we know the moults of thirty, 

 two, and of these, nineteen species form a group characterized 

 by marked sexual differences, the males being very generally 

 conspicuously colored as compared with the females, while in 

 others only the falces are different. Since the nineteen species 

 represent twelve important genera^ it would seem that so far as 

 the North American Attidse are concerned, the generalization is 



1 Jlist. Nat. des Insectes Apteres, I, p. 481. 



2 We have, in tlie genus PJddippus, sixteen species, four pairs, four single males 

 and eight single females. P. cardinalis, male, is of a splendid, uniform, cardinal 

 red; to wlilch of the eight plainly attired females he belongs we do not know; and we 

 have the same difficulty in other cases. 



3 Phidippus. Philmus, Plexippus, Detidryphantes, Ictus, Hahroc est am, Astia, 

 Zygoballas, SynageleSi Menemerns, Lyssomanes, and Epiblemum, 



