290 ARTHROPODS. 



lost their tendency to fight when the mating season was 

 over." 



The courtship is prolonged and elaborate, the females are 

 not only coy but often savage. The male's love-making is 

 often cut short by his death at the hands or chelicerae of his 

 desired mate. Of course we must be careful not to exag- 

 gerate the subtlety of the mental processes involved in the 

 courtship of animals ; we must also beware of regarding it 

 too crudely. I do not think that any one who reads the 

 romantic account which the Peckhams have given of the 

 spiders which they watched so patiently will doubt that 

 sexual selection exists in a marked degree among spiders. 



" The fact that in Attidae the males vie with each other 

 in making an elaborate display, not only of their grace and 

 agility, but also of their beauty, before the females ; and that 

 the females, after attentively watching the dances and tourna- 

 ments which have been executed for their gratification, 

 select for their mates the males which they find most pleas- 

 ing, points strongly to the conclusion that the great differ- 

 ences in colour and in ornament between the males and 

 females of these spiders are the result of sexual selection." 



It is still, however, quite possible that the colouring and 

 decorations may have arisen as natural outcrops of the male 

 constitution, the characteristics of which are by no means 

 limited to greater vitality or activity. 



Structural Characters of Spiders. 



The form of the body is well-known, — an unsegmented 

 cephalothorax, an unsegmented oval abdomen, and a narrow 

 isthmus between them. 



The chitinous cuticle is often moulted as the spider 

 grows. The abdomen is soft. 



' Colouring is common, often harmonising with the sur- 

 roundings, often a sexual characteristic. 

 There are six pairs of appendages — 



(i) The clawed chelicerae or falces, in which the last 

 joint bends against the second last, contain 

 poison-glands. 

 (2) The leg-like pedipalps, the terminal joint of 

 which is modified in the male for copulation. 



