26 



PECKHAM. 



[Vol. 1. 



degree probable that where there is so close a resemblance 

 between two such complex sets of phenomena, in widely 

 separate classes, they can only have been brought about by a 

 common cause. 



SECONDARY SEXUAL CHARACTERS. 



It is a noticeable feature in the secondary sexual peculi- 

 arities of spiders, beside those of color, which have already 

 been sufficiently dwelt upon, that they are very commonly 

 found in the falces, clypeus, palpi and first pair of legs — that is 

 to say, in those parts of the animal that are plainly in view 

 when the male is paying court to the female ; and it is a fact 

 of great significance that even in the species where sexual dif- 

 ferences are reduced to a minimum we usually find a modifi- 

 cation of one or more of those parts which serve to render 

 the male somewhat more conspicuous or showy than the 

 female. Synagehs picata is a case in point, the sexes being nearly 

 alike, but the male having the first legs flattened and brilliantly 

 iridescent. In several species of the genus Lyssomcmes the sexes 



only differ in the length of 

 the falces and that of the first 

 pair of legs or palpi. ^ 



The ant-like spiders are 

 notable for differences in the 

 falces of the two sexes. Sal- 

 ticus formicarius, (Fig. 3), a 

 common European species, is 

 a good illustration, the female 

 having short, vertical, red- 

 dish black falces, while those 

 of the male are horizontal, 

 much enlarged, and copper 

 green in color. In an ant-like 

 spider from Australia, Synemosyna lupata, (Fig. 4, see p. 27), Dr. 

 Koch describes a very curious development in the falces of the 

 male; their great length, their teeth, and their branching 



Fig. 3. — Salticus formicarius (from C. 

 Kocli.) Riglit-liand figure, male; left-hand 

 figure, female. 



1 Lyssoriiaues viridis, jemineus and ariiazotiicus. 



