424 BULLETIN" 15 8, UNITED STATES NATIONAL MUSEUM 



spines. Posterior processes widened and flattened, the inner edges 

 turned up dorsally and fringed with short spines, the tips with a 

 cluster of larger spines. The center of the segment is raised dorsally 

 above the rest, and its posterior corners are rounded and armed with 

 a row of spines. 



Abdomen 2-segmented, the basal segment wider than the terminal, 

 with broad lateral flaps which are turned down ventrally, causing 

 the lateral margins of the segment to appear straight in dorsal view. 

 Terminal segment with a semicircular distal end, to the margin of 

 which the caudal rami are attached; these are broadly lamellar, a 

 little longer than wide, each tipped with four short setae of about the 

 same length. 



Terminal segment of first antenna minute and scarcely visible; 

 second antenna with very stout terminal claws, strongly curved. 

 Terminal claw of maxillipeds with two stout teeth on its inner mar- 

 gin ; horny process on first exopod large, on second and third exopods 

 rather small. Spermatophores elongate and cylindrical, lying flat 

 upon the ventral surface of the genital segment, with a small curved 

 knob at the free end. Total length, 14 mm. ; width of carapace, 8 mm. 



Male. — Carapace similar to that of female, wider than long, its 

 lateral lobes reaching behind the posterior margin of the median 

 lobe. As in the female, the inner margins of these lateral lobes 

 have a double transparent flap, the dorsal one with an accessory tab 

 turned backward near the end of the lobe. Fourth segment longer 

 than in the female, its dorsal plates rudimentary, in the form of 

 rounded projections from the sides of the segment. Genital seg- 

 ment twice as long as wide, widest near the anterior end, with 

 straight lateral margins and rounded posterior corners. No leg rudi- 

 ments appear dorsally, but one pair can be seen ventrally near the 

 posterior corners. Abdomen 2-segmented, the basal segment nar- 

 rower and shorter than the terminal. Caudal rami large flattened 

 laminae longer than wide, each with four apical setae, the second 

 inner one the longest, the outer one the shortest. Total length, 

 11 mm. 



Remarks. — This is the largest species of the genus and may be 

 recognized by its size and by the peculiar inner margins of the 

 lateral lobes of the carapace with their accessory tabs, which show 

 up distinctly in dorsal view. 



Family PANDARIDAE 



Genus PERISSOPUS Steenstrup and Lutken, 1861 



Female. — Head fused with first segment, carapace wider than 

 long; second, third, and fourth segments free, each with a pair of 

 dorsal plates, those on the second segment lateral and oblique, on 

 the third segment median and horizonfal, on the fourth segment 



