420 PlKXniEDINGH OF THE NATIONAL MUSEUM. vol. xxxm. 



Frontal plates nearly as wide as the carapace, projecting over the 

 bases of the first antennae and thus very prominent. 



Free thorax segments about the same length but diminishing 

 rapidly in width from in front backwards. The second segment does 

 not entirely fill the space between the posterior lobes of the carapace 

 and only slightly overlaps the inner margins of the secondary lobes; 

 its lateral plates are broad and enlarged at the tip into a spathulate 

 form, the posterior margin being nearly straight. Fourth segment 

 one-fifth narrower than the genital segment, its lateral margins with 

 a narrow, sharp curve at the center. Genital segment elliptical, much 

 longer than wide, with evenly rounded corners. Fifth legs small and 

 blunt, slightly enlarged at the tips and carried forward some distance 

 in front of the sixth pair; the latter are a little longer, are situated 

 at the posterior corners, and nearly always curve inward toward the 

 mid-line. Inside of each and close to its base, on the posterior margin 

 of the genital segment, is a single large spine. Abdomen elongate, 

 longer than wide, the two joints of the same length; the basal one 

 spindle-shaped, the terminal one wedge-shaped, with no protuber- 

 ance between the bases of the anal lamina^; the latter are nearly 

 twice as long as wide, with the ends rounded diagonalh^ the outer 

 margin being the longer. Each is armed with four seta3, the iimer of 

 which is removed some distance from the others. 



The first antennae are the normal size and shape, the basal joints 

 being almost wholly covered by the projecting ends of the frontal 

 plates. The first adhesion pads are ovate, with their longitudinal 

 diameters inclined at an angle of 45° to the body axis. They are 

 placed so near the edge of the carapace behind the first antennne that 

 nearly half the pad projects beyond the carapace and is visible in 

 dorsal Yiew, affording a good secondary means of identification of the 

 species. The second pair is just outside the bases of the second 

 antenna?, elliptical in form, with their long diameters parallel to the 

 body axis. 



The third pair are egg-shaped and in the usual position between 

 the first maxillipeds; the fourth pair are elongate-elliptical, on the 

 lateral margins of the second segment lobes, and parallel with the 

 body axis. The first and second pairs are nuich smaller in the male 

 than in the female, which would show that they do not function as 

 clasping organs. 



The second antenna^ are larger than in the female; the two basal 

 joints are considerably swollen besides sharing in the formation of the 

 adhesion pad. The terminal claw is large and stout and is armed on 

 its outer margin with two large accessory spines, one near the base 

 and the other at the center. 



The first maxiUipeds have a stout basal joint and a short and 

 slender terminal joint, with two accessory claws on its inner margin 



