94 AMERICAN SPIDERS 



the palpus, brought about by contractions of the muscles of the 

 body. 



The female retains the viable sperms in her receptacles for long 

 periods and dispenses them at the time of egg laying. Although the 

 epigynum has two separate pouches without communication, it is 

 not necessary for the male to supply both of them with sperms to 

 accomplish the impregnation. This usually happens, however, in- 

 asmuch as the male exhausts one palpus and then applies the other 

 one to the other orifice. 



Polygamy is the rule in spiders, though habits vary. The female 

 and male, if he escapes safely, may pair again. After an initial copu- 

 lation the female may reject forcibly any male that approaches her, 

 or may submit many times to various males, even after her eggs 

 have been laid. In some spiders it is probable that only a single 

 coition occurs, the epigynal openings being blocked with a tough 

 plug following mating. This is especially noticeable in the com- 

 mensal comb-web spiders, Conopistha and Rhomphaea, in which the 

 epigynum is capped with a hard conical cover. In many of the 

 small species of Aranea, notably those of the mineata and juniperi 

 groups, the separate epigynal openings are plugged with a black 

 material so tough that in some instances it has been described as an 

 integral part of the epigynum. In the mated Peucetia, the green 

 lynx spider, the epigynum is covered with a hard blackish layer, 

 probably composed of dried semen and collateral liquid, and there 

 is usually present a small process from the male palpus, broken off 

 during the mating a fact which aids greatly in associating the 

 proper male and female when there are more than one species of 

 Peucetia in a particular region. 



PALPUS AND EPIGYNUM 



The pedipalps are the second pair of appendages of the head and 

 lie on each side of the mouth, being inserted behind the chelicerae. 

 They are six-segmented organs consisting, from base outward, of 

 coxa, trochanter, femur, patella, tibia, and tarsus, and thus lacking 

 the additional metatarsal segment present in the legs. The basal 

 segment is the coxa, and it usually bears a conspicuous lobe, the 

 endite or maxilla, that lies at the side of the labium and serves as a 

 cutting and crushing instrument while feeding. The remainder of 

 the pedipalp is the leglike palpus, whose tarsus is ordinarily armed 



