NO. 19 NEW PARASITIC COPEPODS WILSON 5 



The female. — Cephalothorax, including the posterior lobes, less 

 than half the entire length (42 percent) and a little wider than long, 

 the frontal margin strongly curved and emarginate at the center, the 

 posterior corners produced into short lobes narrowed distally. Second 

 and third segments slightly fused centrally but completely separated 

 laterally. The posterior corners of the second segment each carry a 

 rectangular lobe projecting diagonally backward inside the carapace 

 lobes and reaching beyond the tips of the latter. The third segment 

 is considerably narrower than the second but its posterior corners are 

 slightly prominent. The fourth segment carries a pair of fused dor- 

 sal plates, the combined width of the plates and segment being equal 

 to that of the third segment and a little more than half that of the 

 genital segment. These plates are semicircular in outline and cover 

 the posterior portion of the dorsal surface of the segment. In front 

 of them the anterior part of the segment is narrowed into a short 

 neck, which is the same width as the narrowed posterior portion of 

 the third segment (fig. 15). 



The outline of the genital segment is an elongated ellipse, twice as 

 long as wide, divided in front of the center by lateral sinuses and a 

 ventral groove into two unequal portions. The anterior portion is 

 narrowed into a short neck behind the fourth segment, which is the 

 same width as the neck between the third and fourth segments and 

 gives the latter segment a peculiar isolated appearance. The corners 

 of this anterior portion of the genital segment are narrowly rounded. 

 The posterior portion of the segment is twice the length of the 

 anterior and a little wider, with parallel lateral margins and broadly 

 rounded posterior lobes. The sinus between the lobes is wider and 

 deeper than in crypturus and shows a little of the abdomen at its base. 

 Otherwise the abdomen and caudal rami are completely concealed in 

 dorsal view, since the lobes reach far behind the tips of the rami. 



The abdomen is quadrangular in outline with small circular lobes 

 at its anterior corners, one-jointed, and attached to the ventral sur- 

 face of the genital segment in front of the base of the posterior sinus. 

 The caudal rami are small and curved in toward each other, the two 

 together about as large as the abdomen. The posterior end of each 

 ramus is triangularly tapered, with two terminal setae at the apex of 

 the triangle and one at each lateral corner. 



The appendages are similar to those of crypturus, with the fol- 

 lowing differences. The second antenna (fig. 17) has a shorter and 

 stouter terminal claw, which is considerably enlarged and distinctly 

 segmented near its base. The first maxilla (fig. 18) has a single 



