NO. 3574 COPEPOD CRUSTACEANS — LEWIS 79 



flatter. Free fourth pedigerous segment as in female. Genital 

 segment (fig. 28d) slightly longer than wide, lateral margins flatly 

 convex, posterior surface of segment overlapping dorsal surface of 

 flrst abdominal segment slightly. Fifth legs dactyUform, originating 

 on anterior-medial ventral surface, extending posteriorly and shghtly 

 laterally to posterior medial region of genital segment. Fifth legs 

 with 2 plumose terminal setules, one plumose subterminal setule, and 

 one plumose setule from outer dorsal surface approximately two-thirds 

 the distance from proximal to distal end of leg (fig. 28e). Sixth legs 

 (fig. 28/) small, somewhat irregular, projecting shghtly from posterior- 

 lateral ventral surface of segment and tipped by 2 plumose setules. 

 Abdomen 2-segmented, similar to that of female except dorsal poste- 

 rior projection of first segment not as distinct. Caudal rami some- 

 what more rectangular in shape than those of female, otherwise 

 similar. 



Female and male antennule (fig. 29a) 2-segmented; first segment 

 more than twice the length of second, proximal margin broad, ir- 

 regular, with several small concavities and projections, one concave 

 depression in posterior margin forming articulation surface for small, 

 knoblike projection of platelike area on anterior ventral surface of 

 cephalothorax. Anterior lateral margin of first segment convex, 

 posterior lateral margin almost straight except distaUy where poste- 

 rior lateral surface forms base of small, shelflike extension of distal 

 surface; distal surface narrow, irregular. Anterior and distal ventral 

 surfaces with at least 14 plumose setae. Second segment club shaped, 

 ovoid in cross section, narrow proximally and distally, widest me- 

 dially. Distal medial region of posterior surface with one naked 

 seta, distal surface with 11 naked setae and one spikelike process, on 

 anterior distal corner. Female antenna (fig. 296) 3-segmented, lo- 

 cated posterior and slightly medial to antennule base. First segment 

 irregular, proximal end narrow, distal medial region broad, bearing 

 posteriorly projecting lobe; second segment strongly developed, 

 slightly shorter than first segment, greatest width slightly more than 

 four-fifths the length, distal corner projecting slightly as heavily 

 sclerotized, rounded process (not figured). Third segment and claw- 

 like terminal process continuous, proximal posterior surface with 

 smaU, poorly developed, laminate lobe. Setalike accessory process 

 present on middle of combined segment and terminal process, pre- 

 sumably at junction of segment and terminal process. Male antenna 

 (fig. 29c) 3-segmented; first segment flattened, median third forming 

 adhesion surface. Second segment weU developed, longer than first 

 segment, most of proximal inner surface forming adhesion surface, 

 inner distal surface with 2 heavily sclerotized swellings serving as 

 articulation surfaces for 2 swellings on inner proximal surface of 



