NO. 1573. FARASITin COPE PODS— WILSON. 429 



Male. — Carapace semielliptical, a trifle wider than long, squarely 

 truncated posteriorly, with a long and narrow lobe at each of the 

 posterior corners. Second and third thorax segments not fused, but 

 distinct, of the same length as the fourth segment, the three dimin- 

 ishing regularly in width, and none of them bearing dorsal plates. 

 Genital segment small, a little narrower than the fourth segment, of 

 about the same length and wadth, with reentrant corners. Abdomen 

 very short, the basal joint hardly visible beneath the posterior border 

 of the genital segment. The anal lamini3e are no larger than in the 

 female, but the plumose setge are considerably longer. 



The appendages are like those of the female, with the usual sexual 

 mochfications in the second antennae and the second maxillipeds. 

 There is a greater difference in size between the adhesion pads of the 

 first two pairs than in the female, the first pair being enlarged. The 

 mouth tube is the same, but the second maxillcse are three-jointed, 

 counting the terminal claw; this makes it practically certain that 

 these appendages in the female are also three-jointed, although the 

 two basal joints are usually fused, and they are so designated in the 

 genus diagnosis. 



The arrangement of the spines and setae on the swimming legs is as 

 follows: First exopod, 1, 0; 4, III: endopod, 0, 0; 0, III: second 

 exopod, 1, I; 4, V: endopod, 0, I; 0, VIII: third exopod, 1, I; 3, 

 IV: endopod, 0, I; 0, IV: fourth exopod, 4, III: endopod, 0, IV. 

 The basal joints of the second and third pairs carry a medium spine 

 on their outer corner. 



Total length, 4.55 mm.; length of carapace, 2 nnu.; width of 

 same, 2.3 mm.; length of genital segment, 0.88 nun. 



The male is darker in color than the female and usually becomes a 

 deep brown in alcohol; this color is uniforndy distributed without 

 pigment spots. 



(alatus, furnished with wings. None of the other species have 

 dorsal plates of any size.) 



Young female. — General body form similar to that of the adult; 

 the carapace is proportionally as wide, with broad and well-rounded 

 posterior lobes and prominent frontal plates. The second and third 

 thorax segments fused, with their single pair of lateral plates even 

 more angular than in the adult, for the external margin of these 

 plates is concave, thereby making the corners acute. No plates on 

 the fourth segment as yet; the genital segment very small and ellip- 

 tical, the same width as the fourth segment, and one-half longer than 

 wide. Abdomen entirely visible, one-jointed, with reentrant sides 

 and a convex posterior margin; anal laminas larger and the plumose 

 setae longer than in the adult. 



The only differences in the appendages are such as are common to 

 young forms; the joints are relatively smaller, while the spines and 



