636 



PROCEEDINGS OF THE XA TIONAL MUSEUM. 



VOL. XXVII. 



addition to the regular peg and semen receptacle on the fourth and 

 third legs, respectively, we find on the anterior surface of the third 

 leg a long cluh-.sliaped projection, which arises from the outer end of 

 the basal joint and projects diagonall}^ forward and outward past the 

 distal basipod joint and far out on the exopod (tig. 13). Its surface is 

 smooth and even and it seems to be tactile in function. There is 

 another conical projection, a trifle smaller, on the posterior surface 



Fig. 12. — Sexi'al ()Rgan.s of male ARGrLrs americaxus. h. c. blind fAPsuLE: r. d., EjAcrLATORV 



duct; «. ('., SEMEN VISICLE; t., TESTES; V. d., VAS DEFERENS; I', i ., VAS EFFERENS. 



of the preceding pair of legs, exactly opposite the one just described. 

 This also has a smooth surface and a probable tactile function. To 

 increase this probability both projections are well innervated and their 

 surfaces are plentifully covered with short setw. There are also small 

 projections, varj'ing considerably in diflerent individuals, upon the 

 opposite surfaces of the same joints as bear the large ones. 



