No. 1.] SEXUAL SELECTION IN SPIDERS. 35 



long, white hairs; those of the female are but slightly iridescent, 

 and lack all further ornament. In Dendryphantes elegans the 

 first leg in the male has on the lower half of the tibia a wide 

 fringe of hair, which is very conspicuous as he waves his legs 

 while courting ; while the legs of the female are plain. These 

 leg modifications have been frequently transmitted to the 

 female, so that not uncommonly we find both sexes presenting 

 striking forms, which are, however, proportionately less re- 

 markable in the females than in the males. For example, in 

 Diolenius phrynoides, where the first legs are wonderfully length- 

 ened and modified, those of the female measure 12|- mm., and 

 those of the male 20J mm., being nearly twice as long. The 

 curious change in the legs of this species so impressed 

 Walckenaer as to make him suggest that the spider must walk 

 on the water, since in no other way could such legs be useful. 

 As it is a land species -his explana- ^^^ ^^^ 



tion must be abandoned, and we are ^ ^i 



constrained to look upon these legs f% i\ 



as secondary sexual organs, useless \f m 



for locomotion, but of high import- \LJl ,xL-^ 



ance while mating. To gain a clearer "Tu/ ttn^^""^ 

 idea of this lengthening of the first ^^^^"^^Ly 



legs one has only to imagine that in ^-'? '^^ 



some group of human beings the J/WT^^^ 



arms of the men were doubled in jE // |j ^% \. 



length, while in the women they j^ ^^ 



remained as before. There are nu- (l \ r W 



merous species in this genus, all vJ^^ l^^si^ 

 characterized by their long legs (Fig. vIt'^^T^ 



12). It is not unusual for female as ^^ "''^i 



well as male beetles to possess well -^/ff^^^-^ 



developed horns and knobs, so that '^ ^" ^ %\ k 



. • ji Fig. 12. — Diolenius venustus 



there is nothing anomalous m the (from nature), upper figure, male; 



lower figure, female. 



elongated legs of both sexes of the Dio- 



leidi. In Chirothecia, a South American genus of Aitidx, we meet 



with other instances of modified legs, but here there is a marked 



