Secondary Sexual Characters in the Genus Aranea. 59 



VII. — On some Secondary Sexual Characters in the Genus 

 Aranea, Linn. By F. Pickard-Cambridge, B.A., F.Z.S. 



While recently making an analysis of the characters of the 

 spiders belonging to the genus Aranea {Epeira, auct.), with 

 the object of finding any which might prove valuable in 

 relation to the numerous subdivisions of the group, I have 

 discovered some peculiar to the male sex which have not, I 

 believe, been recorded hitherto. 



It is well known that on the coxa of the first pair of legs 

 there is in very many species a hook-like apopiiysis at its 

 posterior angle beneath, though the use of it has not been 

 recognized. In correlation, however, with this hook I find 

 on the anterior margin of the femora of the second pair of 

 legs, quite at the base, a long groove distally shallow, basally 

 quite deep, bounded in front by a long chitinous ridge. If 

 coxa i. be raised and the second leg depressed this hook will 

 slide down the groove and become locked in the deep pit at 

 the base. 



Again, on the upperside of the coxa of leg i. there is in 

 some species {yertehrata, McCook, and jyurpurascens, 0. P.- 

 Cambr., e. g.) a rounded or sharp tubercle which works 

 against a chitinous ridge beneath tlie raised margin of the 

 carapace. There is, moreover, on the coxal segment of the 

 pedipalp {maxilla) towards its distal extremity a sharp 

 tubercle or spur, which is developed in correlation with a 

 chitinous tubercle at the base of the femur of the pedipalp, so 

 that if the pedipalp were moved rapidly from the trochantal 

 joint the two tubercles would come in contact. Tiiis hist 

 structure has been found in all the species I have hitherto 

 been able to examine. 



At present one can merely record these facts without being 

 able to suggest what may be the precise function of the 

 tubercles and grooves in question. Probably all of them are 

 used, when the male moves the fore legs and palpi rapidly in 

 challenging the female to the combat of love (tor it is literally 

 such amongst members of this particular family, in which 

 the former sex often gets the worst of it), in producing a 

 clicking noise to frighten the female and reduce her to a 

 frame of mind sufficiently reasonable to admit of the approach 

 of the male. 



Possibly, on the other hand, they may have no such function, 

 but may merely be used for locking the fore legs and the base 

 of the pedipalp, to prevent their being wrenched off in the 

 tussle of holding the female with the specialized clasping- 



