140 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 121 



lateral surface, posterior end overlapping junction of cephalothorax 

 and free fourth pedigerous segment, margin flatly convex. Major 

 dorsal cephalothoracic grooves forming irregular H, posterior longi- 

 tudinal legs and crosssbar continuous, heavily sclerotized. Ocular 

 region distinct. 



Free fourth pedigerous segment short, distinct from cephalothorax, 

 incompletely separable from genital segment; segment sharply angled 

 posteriorly and anteriorly, from region of fourth leg attachment. 

 Genital segment (fig. 52c) broad for most of length, anterior end con- 

 cavely angled inward, posterior end with pair of broad lappets dor- 

 solaterally, lappets extending posteriorly past junction of genital 

 segment and abdomen. Fifth legs (fig. 52d) consisting of single, 

 plumose setule arising from ventral lateral surface at anterior end of 

 lappets. Spermatophores visible on single Hawaiian specimen, 

 attached immediately ventral to junction of genital segment and 

 lateral surface of abdomen. 



Abdomen indistinctly 2-segmented, junction vnth genital segment 

 distinct. First segment approximately five times the length of 

 second, broadest in anterior medial portion, irregularly curved to 

 anterior and posterior ends; second segment with flatly convex lateral 

 margins, anal indentation slight. Caudal rami (fig. 52e) approxi- 

 mately iy2 times as long as mde, distal half of inner surface plumose; 

 three plumose setae present on distal surface, single plumose seta on 

 outer distal siu"face and 1 plumose setule on either side of setae. 



Antennule (fig. 52g) 2-segmented, attached to lateral-anterior 

 ventral surface of cephalothorax. Firet segment slightly less than 

 tAnce the length of second, broader proximaily than distall}^; ventrally 

 curved distal half of anterior surface mth approximately 18 plumose 

 setules. Second segment rodlike, distal end M'ith approximately 12 

 naked setules. Antenna (fig. 52h) 3-segmented, attached medial and 

 posterior to antennule base. First segment squat, UTegular, heavily 

 sclerotized; second segment tapered slightly from broad proximal to 

 slightly narrower distal end, proximal outer surface -with small, sub- 

 triangular projection. Thhd segment and clawlike terminal process 

 indistinctly separable, segment elongate, wdth small, lappet-like pro- 

 jection from posterior medial surface. 



Mandible (fig. 52/;,) 4-parted, rodlike, distalmost part ciu-ved 

 inward, with 12 denticulations on inner surface. Postantennal process 



Figure 52. — Caligus pelaviydis Kr0yer, 1863, female: a, dorsal view (broken line=nick in 

 specimen). Ventral view: b, posterior cephalothoracic sinus; c, genital segment (anterior 

 end directed downward); d, fifth leg; e, caudal ramus;/, right side of frontal region showing 

 lunule and antennule base; g, right antennule; h, oral region, left side showing antenna, 

 postantennal process, mouth cone, mandible, maxillule, postoral process, and maxilla 

 base; i, left maxilla;;', left maxilliped; k, sternal furca. 



