378 PROCEEDINGS OF THE NATIONAL MVSEUM. vol. xxxm. 



two-fifths as long, the median sinus two-thirds the entire length, 

 narrow and enlarged a little at the base. 



Each plate is rounded in the form of a semicircle at its posterior 

 end and at the anterior corner, the latter projecting prominently. 

 Genital segment five-sevenths the width of the carapace, a little less 

 than twice as long as wide, with parallel sides and wide, evenly 

 rounded, but very short posterior lobes. The dorsal plates on this 

 segment are a little narrower and shorter than the segment itself, 

 their posterior ends cut off obliquely and separated by a short sinus. 



Dorsal process of the sixth segment filling little more than half the 

 entire space between the posterior lobes of the genital segment, but 

 not reaching quite to their tips. Dorsal plates of this segment shorter 

 and wider than the process, the median sinus less than one-third their 

 length and enlarged a little at its base. Abdomen one-jointed, sub- 

 triangular, the anterior corners rounded, the posterior margin pro- 

 jecting slightly beyond the genital segment. Anal laminae huge, as 

 long and two-thirds as wide as the dorsal plates on the fourth seg- 

 ment, and armed with short, nonplumose spines. Egg strings 

 narrow and about four times the length of the body; eggs small and 

 very numerous. 



First antennae small, two-jointed, armed with but few setie, both 

 joints visible in dorsal view. Mouth tube very long and narrow; 

 maxillae curved in toward the base of the mouth tube and then out 

 again, so as to assume the shape of a half moon. Each maxilla three- 

 jointed, the two basal joints subequal, the terminal joint much 

 shorter. First maxillipeds rather large, the two joints approxi- 

 mately the same length; the accessory claw on the posterior margin 

 of the distal joint is removed some distance from the terminal claw. 

 Both claws are flat and laminate and fringed along both margins with 

 cilia; between them and nearer to the base of the terminal one is a 

 rounded knob carrying a heavy tuft of setae. 



Second maxillipeds not swollen as much as in some of the other 

 species, and armed with an ordinary terminal claw which shuts down 

 against two corrugated knobs on the basal joint. 



All the swimming legs biramose and of the usual pattern; the 

 proximal joint of the exopod of the first pair is enlarged more than 

 in any other species, being more than five times the size of the distal 

 joint. The arrangement of the spines and setae on the different legs 

 is as follows: First exopod, 1, 0; 3,111: endopod, 0, 0; 0,111: second 

 exopod, 1,1; 1, I; 3, IV: endopod, 1, I; 0, II; 0, VII: third exopod, 

 1, I; 1, I; 3, IV: endopod, 0, I; 0, II; 0, IV: fourth rami without 

 spines or setae. 



The legs on the sixth segment are reduced to mere stumps, attached 

 to either side of the segment and projecting outward at right angles 

 to the body axis. They are bluntly rounded at the tips which just 



