470 BULLETIN 158, UNITED STATES NATIONAL MUSEUM 



Male. — Carapace one-third longer than wide, its lateral margins 

 with a double curve, its posterior corners produced into prominent 

 lobes, each tipped with a stout spine. Second, third, fourth, and 

 fifth segments diminishing in length and width backward, the sec- 

 ond segment narrower and much shorter than the carapace. Genital 

 segment considerably wider than the fifth segment and tapered dis- 

 tally, as long as the three preceding segments combined, with leg 

 rudiments on its lateral margins near the posterior end. Abdomen 

 4-segmented, two-thirds as long as the rest of the body, the segments 

 diminishing in length and width backward, the anal segment about 

 one-third the length and a half the width of the basal segment. 

 Caudal rami one-half longer than the anal segment, four times as 

 long as wide, each tipped with three long equal plumose setae and a 

 much shorter one at the outer corner. 



First antennae like those of the female, the claws on the second 

 segment longer and sharper, and the spines longer and more numer- 

 ous. The second segment of the second antenna has a stout process 

 on its dorsal surface near the proximal end; the terminal claw is 

 long and slender and carries two accessory spines on its inner mar- 

 gin at the base. The second maxilla is 2-segmented, the second seg- 

 ment a little shorter than the first and tipped with a stout claw ; at 

 the distal end of the second segment near the base of the claw is a 

 transverse row of long hairs and a slender blunt spine at the end of 

 the row. The maxillipeds are uncinate and not chelate as in the 

 female, 3-segmented, the basal segment stout with a small knob 

 on its anterior margin near the base; the second segment is much 

 shorter and more slender, the terminal segment is in the form of a 

 curved claw, with a knob tipped with a seta on its inner margin near 

 the base. 



Eami of first four pairs of legs 3-segmented, the segmentation 

 more distinct than in the female. The arrangement of the spines 

 and setae on the three segments of each ramus is as follows: First 

 exopod, 1-1, 1-1, 2-5; first endopod, 1-1, 1-2, 1-5; second exopod, 

 1-1, 1-1, 3-6; second endopod, 1-1, 1-2, 2-5; third exopod, 1-1, 1-1, 

 2-6; third endopod, 1-1, 1-2, 2-4; fourth exopod, 1-1, 1-1, 2-5; 

 fourth endopod, 1-1, 1-2, 2-2. In the terminal endopod segment of 

 the second legs one of the spines lies between the two outer setae, at 

 the outer corner of the segment, and in the same segment of the third 

 legs two spines are thus situated. This armature of the legs is quite 

 peculiar and differs from that of the female and also from that of 

 the similis male described by T. Scott.^*^ Total length, 2 mm. 

 Width of carapace, 0.3 mm. 



Remarhs. — This species can be recognized at once by the large 

 curved claws and the wide lamina on the second segment of the 



" 20th Ann. Rep. Fishery Board Scotland, p. 296, pi. 12, 1902. 



