No. 1.] SEXUAL SELECTION IN SPIDERS. 27 



fangs, reminding one of the great mandibles in certain male 

 Lvmnidx. The female is undescribed, but we know, in this 

 genus and in others closely related, so many males that have 

 enlarged falces while those of the 

 female are short, that this, too, is 

 doubtless a sexual characteristic* 



Cambridge has described two spid- 

 ers from Ceylon^ which are remark- 

 able for the great elongation of the 

 male falces, these being in both 

 species longer than the cephalotho- 

 rax, while the fangs are toothed and 

 equal in length to the falx. In both 

 species, too, the falces seem to be 

 attractively colored, as in one they 

 are "dark black-brown and shining," 

 and in the other "very slightly and 

 transverselj' rugose, and shining in 

 some lights with an opaline hue." It Fig. 4.-svneraosyna lupata. 



, , , Male (from L. Koch). 



IS true m many males that the 



falces are not only greatlj^ enlarged but are also brilliantly 

 colored; and in this connection it is of high importance to note 

 that the brightly colored hairs or metallic scales, as well as the 

 protuberances, are either on the anterior surface, or in some 

 way so jalaced as to be plainly in view from in front. 



In a common spider of the Southern and Eastern United 

 States IcivjS pahnarum Hentz we have a good illustration. 

 In the male the falces are compressed and horizontal and are 

 three times as long as the face, the fang equaling the falx in 

 length. The front surface of the falces is dark bronzy rufus and 

 on each outer edge is a wide band of snowy white hairs. In 



1 We have examined 49 species of ant-like spiders, but in no instance have we 

 found a female with long falces, while we know of 19 males in which they are much 

 lengthened. One might have expected to iindthat an occasional female had inherited 

 the modification from the male, but it seems to be, in this group, strictly limited to 

 one sex. 



2 Ann. and Mag. of JS'at. Hist., 1869, pp. 68-70. 



