ART. 5. NORTH AMERICAI^ PARASITIC COPEPODS WILSON, 77 



the rami plus their spines. The third legs are uniramose, one-jointed, 

 and armed near their tip with three minute spines. The fourth legs 

 project from the lateral margins of the fused posterior body, just 

 behind the rudimentary plates of the fourth segment. Each is a 

 minute, uniramose, fingerlike process, with two tiny spines at its tip. 



Color. — Fresh living specimens are bright red, owing to the blood 

 they contain. The elongate convoluted oviducts are brownish black, 

 deepening into jet black in the deeper portions of the convolutions, 

 especially toward the posterior end of the body. The egg cases are 

 dark brown. Preserved material is light brownish yellow, the dorso- 

 ventral muscles slightly darker. 



Total length, including the posterior processes, 16 mm. Width of 

 carapace, 1.50 mm. Width of posterior body, 1.90 mm. Length of 

 ^g% strings, 21 mm. 



Specif G characters of male. — General form that of a Greek cross, 

 due to the elongate, rigid fourth legs, which project from the lateral 

 margins near the center of the body. Cephalothorax, the largest 

 division of the body, subovate, nearly as wide as long, with a slight 

 rostrum projecting from the center of the anterior margin, and a 

 chitinous framework visible through the dorsal surface. Both pairs 

 of antennae show in front of the carapace in dorsal view, while the 

 second maxillae project considerably on either side, and the maxilli- 

 peds stand behind the posterior corners like a pair of large lobes. 

 Behind the head and more or less fused with it the first thorax seg- 

 ment appears as a short neck, reduced to less than half the width of 

 the head. The second segment is considerably wider and at least 

 four times as long as the first, with the swimming legs projecting 

 from the lateral margins. The third segment is a little wider, but 

 shorter, than the second, and in the living male the third legs project 

 from its sides, but in preserved material they shrink back so as to be 

 invisible in dorsal view. The fourth segment is still wider than the 

 third and longer than the second, and from its lateral margins ex- 

 tend the fourth legs, which are long, cylindrical, and rigid, and which 

 extend outward and backward at an angle of about 60° with the body 

 axis. The fifth and genital segments are the same width as the 

 fourth and are suboval in outline, with a single long and jointed seta 

 on each lateral margin near the center. The abdomen is reduced to 

 less than half the width of the genital segment, with concave lateral 

 margins and a sinus at the center of the posterior margin. The anal 

 laminae are longer than the abdomen and widely divergent ; each is 

 flattened dorsoventrally and emarginate at the tip, which is bluntly 

 rounded and armed with a row of minute spines, one of which, at 

 the tip of the lamina, is larger than the others. 



The first antennae are apparently three-jointed and taper from the 

 base to the tip. The setae at the tip are not symmetrically arranged, 

 3136— 22— Proc.X.M. Vol.60 13 



