NO. 1531 . A DDITIONA L NO TES ON THE A R G ULJD. E— WILSON. 413 



papillfe basal and minute. The accessory sexual characters are very 

 prominent and markedly different from those of any other species. 



In the fourth legs both joints of the basipod carr}' a tiap, heavily 

 fi'ing-ed with plumose seta? on their posterior margin, that on the ])asal 

 joint being- several times hirger than that on the proximal. The peg- 

 on the anterior margin of the proximal joint is quite similar to that 

 in A /'(/>/! us 'Versicolor^ but relatively larger. The two parts of the peg, 

 basal and terminal, are more clearly defined than in any species yet 

 examined, and to<^ether make a pear-shaped organ with an evenly 

 rounded outline. The tip of the tube is enlarged and surrounded by a 

 fringe of minute hairs as in other species. The basal portion of the 

 peg connects on the inside of the leg with a long spindle-shaped 

 receptacle which extends inward through both joints of the basipod 

 and almost to the mid-line of the body. Its walls are muscular and no 

 doubt aid in ejecting- the sperm. 



In the third legs the proximal joint of the basipod is semi-lunar 

 and the ends curve outward in long flaps, one in front of and the other 

 behind the terminal joint. The posterior flap is wide and bluntly 

 rounded at the tip; it carries a heavy fringe of plumose setse and 

 reaches only to the center of the distal basipod joint. The anterior 

 flap is narrower and tapers to a long curved point which overlaps the 

 base of the exopod for some little distance. There are no plumose 

 seta^ on its margin, but instead its entire dorsal surface is covered with 

 small spines. 



The distal joint of these third basipods bears the semen receptacle 

 which is also similar to that of Argulus versicolor^ except that the 

 opening- is nearer the center on the dorsal surface, instead of being- at 

 the posterior margin. 



There is also a cone-shaped funnel extending- forward from the 

 anterior margin of the opening-, along the dorsal surface of the basipod. 

 This cone has a slit running along the dorsal side for the whole length; 

 the outside of the cone and the inside at the tii) are covered thickly 

 with small spines. 



The receptacle inside these legs is cylindrical and extends inward, 

 like that of the fourth legs, through both basipod joints and into the 

 third thorax segment. 



The base of the exopod of these legs is enlarged on its anterior 

 border where it joins the basipod into a rounded knob thickly covered 

 with short spines. 



The basal joint of the second legs bears a small flap on its posterior 

 margin and ventral surface similar to those on the other legs but much 

 smaller. It carries only four plumose setas, at its outer end. The 

 distal joint of the basipod of the first and second legs is armed with a 

 flagellum. which projects from its ventral surface at the outer anterior, 

 corner. 



