no. 1404. PARASITIC COPEPODS—CALIGIDJE— WILSON. 629 



Male. — Carapace as in the female, except that it is relatively much 

 larger, five-eighths of the entire length (fig. 245). 



Free thoracic segment considerably shortened by the overlapping of 

 the median lobe of the carapace. Unlike the condition in most males 

 this segment is not proportionally wider than in the female. The gen- 

 ital segment and the abdomen together form an almost perfect oval, 

 the widest end being anterior, while it narrows rapidly posteriorly. 



The genital segment is one-third the length of the carapace, consid- 

 erably wider than long, and squarely truncated posteriorly. It is fur- 

 nished with two pairs of large papillae — one on the lateral margins, 

 one-third the distance from the posterior end, the other pair at the 

 posterior corners. In both pairs the papillae are sharply conical and 

 furnished with quite large plumose seta. The testes are very large, 

 elongate-elliptical in shape, and they fill nearly the entire segment. 

 The semen ducts open on the posterior ventral surface, on either side 

 of the abdomen. The abdomen and the anal papillae are similar to 

 those of the female. There is the usual difference in the appendages, 

 but, while the second antennae are increased in size, they are not 

 branched as much as in most species. 



Instead, at their bases are two large corrugated ridges of chitin, 

 inclined diagonally outward from the mid line, which serve to prevent 

 slipping. 



Total length 3.6 mm. Length of carapace 2.2 mm.; width of same 

 2.2 mm.; length of genital segment, 0.8 mm.; length of abdomen 

 0.3 mm. 



Color as in the female. 



(edwardsi, to Vinal N. Edwards, of the United States Fish Com- 

 mission at Woods Hole, who discovered the species and collected 

 nearly all the specimens.) 



Nawplius. — Body obovate or slightly spindle-shaped in outline, and 

 almost exactly twice as long as wide. The posterior end is quite 

 squarely truncated, while the anterior end is well rounded (figs. 39 

 and 257). 



There are the usual three pairs of appendages, which do not differ 

 in form from those of other nauplii, except perhaps that they are a 

 little stouter. But the balancers on either side of the anus are consid- 

 erably shorter and wider than in most nauplii examined. They are 

 also considerably swollen at the outer ends and somewhat curved. 



The pigment is a distinctive bright purple, foreshadowing that of 

 the adult, but it is distributed very sparingly in irregular patches, 

 which vary much in position, size, and shape. Sometimes there are 

 three pairs of patches along the sides of the posterior part of the 

 body, a central patch between the anterior pairs, and an anal patch, 

 each resembling a piece of tattered cobweb. But more often there is 

 no regularity whatever in the arrangement, the only constant factor 



