710 PROCEEDINGS OF THE NATIONAL MUSEUM. toi. xxxi. 



but the fiffj legs show a distinct exopod and endopod instead of a sin- 

 gle triangular stump, which is exceptional in females. 



Total length, 12 mm. Length of carapace, 5.9 mm. Width of same, 

 6 mm. Length of genital segment, 3.1 mm. Width of same, 3 mm. 

 Length of abdomen, 2.5 ram. Length of egg-strings, 15 mm. Of a 

 grayish horn color, nearly uniform throughout, and not quite as trans- 

 parent as gracilis. 



{glaher., smooth.) 



Male. — Carapace distinctly longer than wide and obovate or acorn- 

 shaped, with the widest portion very far back. Posterior sinuses tri- 

 angular and flaring widely. Free thorax segment long and narrow, 

 less than half the width of the genital segment; dorsal plates so rudi- 

 mentary as to be indistinguishable. 



Genital segment narrow, spindle-shaped, squarely truncated posteri- 

 orly, with a conical papilla projecting outward and backward from 

 each corner and terminating in three small spines. 



These are the rudiments of the sixth legs, those of the fifth pair 

 appearing at about the center of each side of this genital segment and 

 showing a distinct exopod and endopod. 



The abdomen is made up of two nearly equal segments, without the 

 ^^'ings, which appear in the female. The anal laminae and their set^e 

 are relativ^ely much larger than those in the female. 



The second antenna? are branched like those in the male of graciUs; 

 the other appendages are the same as in the female, except the second 

 legs. Here in place of the large claws upon the exopod we find a pair 

 of curious structures upon the outer distal margin of the second exopod 

 joint. The outer of these is much the larger, conical in shape, nearly 

 as large as the joint itself, and covered with small spherical warts or 

 papillaB. The smaller inner one is narrow, cylindrical in form, and 

 two-jointed, the basal joint being four times as long as the terminal, 

 with no peculiarities visible. 



Total length, 7.6 mm.; length of carapace, 3.5 mm.; width of same, 

 3.1 mm.; length of genital segment, 1.25 mm.; width of same. 1.1 

 mm.; length of abdomen, 1.35 mm. 



Color similar to that of the female. 



MetanaupUus (tigs. -1-9). — One thorax segment fused with the head 

 to form the carapace, which is spindle-shaped, the two ends about 

 the same size and both emarginate (Hg. 1). Eyes very large and situ- 

 ated just in front of the center of the carapace on the mid-line. 



Frontal plates distinct, but widely separated and folded over on the 

 ventral surface. Second thorax (first free) segment wider than the 

 rest of the thorax and abdomen, its sides strongly convex. Third seg- 

 ment about the same length as the second, but narrower and its sides 

 not as convex, though still well curved. Fourth and genital segments 

 united with the abdomen into a segment only one-fourth longer than 

 the third segment, with concave sides and well-rounded corners. 



