314 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.55. 



membrane found on the lobes of this segment in ornatus, the present 

 species has a conical process extending backward parallel with the 

 abdomen and ending in three small spines, with a row of similar 

 spines along the inner margin. 



The abdomen is two- jointed and cylindrical, the basal joint the 

 same width as the terminal but less than half as long. The terminal 

 joint tapers uniformly backwards and is bluntly rounded posteriorly. 

 The lateral margins are smooth, but there is a double row of spines 

 along the center of the dorsal surface. The anal laminae are linear, 

 two-thirds the length of the terminal joint and tipped with small 

 spines. The second antennae are stout, the basal joint armed pos- 

 teriorly with a wide flat spine, the terminal claw strongly curved 

 and without an accessory spine. Maxillary hooks three-parted, the 

 two inner prongs fused and much smaller than the outer one. Max- 

 illae comparatively large and bifurcate, the outer ramus longer and 

 wider than the inner one; between the rami projects a stout spine 

 attached to the ventral surface of the head. 



The furca is compound, the posterior rami bifid, the lateral ones 

 simple; on either side of the tip of the furca is a secondary furca, at- 

 tached to the head and projecting ventrally. 



The first legs have three-pronged claws like those of ornatus; the 

 rami of the third legs are widely separated and two- jointed. The 

 basal joint of the exopod is armed with a large three-pronged claw, 

 quite different from the one in ornatus. The fourth legs are large 

 and stout, the basal joint longer than the three terminal ones; the 

 latter are distinctly separated, the second and third joints with one 

 claw, the fourth joint with three, the terminal one larger than the 

 others. The egg strings in both females were broken. 



JSpeciflc characters of male. — Carapace considerably elongated, but 

 still quite squarely truncated posteriorly ; areas and markings similar 

 to those of the female; the posterior ribs in the lateral areas are 

 strengthened even more than in the female, since they have two sup- 

 porting ribs at their base instead of one. The dorsal plates of the 

 fourth segment are nearly circular in outline, with a triangular 

 sinus between their bases on the median line. While they extend 

 laterally considerably beyond the margins of the genital segment 

 they do not reach posteriorly as far back as in the female. The 

 genit-al segment is less than half the width of the carapace, longer 

 than wide, narrowed into a waist where it joins the fourth seg- 

 ment, and convex posteriorly. At each posterior comer is a wide 

 process, flattened laterally, and extending diagonally outward and 

 backward to about the level of the center of the abdomen. These 

 processes taper gradually and are tipped with two small spines. 

 The abdomen is two-jointed and relatively the same as in the 

 female. 



