NO. 1573. 



PARASITIC COPEPODS- WILSON. 421 



close to the base of the terminal claw. The ventral of these two 

 claws is more than twice the size of the dorsal. The second maxilli- 

 peds are much enlargt^l, relatively more so than in the female, and 

 evidently they, with the second antennae, form the cliief clasping 

 organs. They are armed with a stout and well-developed terminal 

 claw, which shuts down against a group of three tuberculated knobs 

 placed side by side on the basal joint. This combination of claw and 

 forceps pinchers gives these copepods a very hrm hold upon their host. 

 The arrangement of the spines and set* on the swimming legs is 

 as follows : Fh-st exopod, 1, 0; 4, III: endopod, 0, 0; 0, III: second exo- 

 pod, 1,1; 4,YI: endopod, 0, 1; 0,VIII: third exopod, 1,1; 4, V: endopod 

 0,1 ; 0, V : fourth exopod, 1 , 1 ; 4, V : endopod, 1 , 1 ; 0, V. The sperm duct 

 is coiled into a large bunch near the center of the genital segment on 

 either side, and its posterior end then opens into a boot-shaped 

 spermatophore receptacle which lies })etween the bunch and the 

 posterior end of the genital segment, and whose long diameter is 

 inclined at an angle of 45° to the central axis. The anterior end of 

 this receptacle is narrowed into a sort of pointed appendix which 

 curves around forward and inward. The posterior end is bhmtly 

 rounded and from it a short tube leads to the genital opening, which 

 is near the jjosterior corner of the genital segment. 



Total length, 7.23 mm.; length of carapace on the mid line, .3 mm.; 

 width of same, 4 mm.; length of free segments, 1.63 mm.; of genital 

 segment, 1.72 mm.; of abdomen, 1 mm. 



Color the same as that of the female except that there are no pig- 

 ment spots or blotches and the body is quite transparent. 



Young femalc^.^The smallest female thus far obtained is a little 

 less than '5 mm. in length (fig. 182). In this the carapace is nearly 

 half the entire length, as long on the mid-line as it is wide, with nar- 

 row lateral areas and short triangular posterior lobes. The posterior 

 margin between these lobes is very wide and irregularly sinuate, the 

 geneml direction being nearly straight. Eyes plainly visible one- 

 third the distance behind the frontal margin, three in number, 

 arranged in a triangle, the middle one posterior. Frontal plates wide 

 and prominent and covering the whole of the basal joints of the fost 

 antennae. Lateral areas divided considerably behind their center 

 by a transverse groove representing the boundary line between the 

 head and the first thorax segment. Second segment filling the entire 

 space between the posterior lobes of the carapace, its lateral plates 

 short, broad, and well rounded at their tips. The median plate of 

 this segment has not yet been differentiated, but the two lateral plates 

 are fused in a wide band across the mid-line. The dorsal plates of 

 the third and fourth segments have just started and over hip the seg- 

 ments following them sc^arcely at all. The genital segment is elliptical, 

 much smaller than in the adult female (less than half the width and 



