NO. 3574 COPEPOD CRUSTACEANS — LEWIS 103 



external surface of K. pelamis (Linnaeus) captured by Robert 

 Stevenson near Oahu, Hawaii. 



Measurements. — (In mm) 13 females and 10 males: 



female male 



Description.— Female cephalothorax (fig. 37a) consisting of ceph- 

 alon and first 4 thoracic segments, with several hairlike processes 

 scattered over dorsal surface. Frontal region approximately one- 

 fifteenth the length of cephalothorax, with narrow membrane along 

 anterior margin; lunules large, projecting posteriorly, on ventral 

 surface, past division between frontal region and remaining cepha- 

 lothorax. Lateral cephalo thoracic margins slightly irregular, with 

 fine membrane, also with distinct socket-shaped depression poste- 

 riorly. Posterior sinus (fig. 37c) distinct, U-shaped, with finely serrat- 

 ed membrane along outer margin. Posterior median cephalothoracic 

 region projecting slightly past lateral cephalothoracic regions, poste- 

 rior margin flatly convex. Major dorsal cephalothoracic grooves 

 forming irregular H , with posterior and anterior longitudinal grooves 

 flaring outward, anterior extending to just posterior to ocular region. 

 Ocular region distinct, pigment cups, containing lens element, con- 

 tiguous on median longitudinal axis of body. 



Female fourth pedigerous segment free, width approximately 

 three times the length, dorsal sm-face raised slightly, appearing 

 platelike. Genital segment (fig. 37d) distinct from fourth pedigerous 

 segment, anterior end narrower than posterior, lateral margins wavy. 

 Posterior lateral regions of genital segment lobate, projecting pos- 

 teriorly slightly, bearing fifth legs on outer surface. Fifth leg (fig. 37/) 

 consisting of 2 adjacent nodes, first bearing single plumose seta, 

 second bearing 3 plumose setules. Median posterior surface of 

 genital segment indistinctly and incompletely separable from abdo- 

 men. Abdomen considered 4-segmented by most workers although 

 only 2 distinct divisions (3 segments) present, third division suggested 

 by constriction. Anterior part of abdomen with constriction and 

 may represent 2 segments although constriction superficial and 

 developing eggs extend from genital segment through full length of 

 first part of abdomen. Anterior part also with small, bean-shaped 



