164 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 121 



Holocentrus xantherythrus Jordan and Evermann, from the Honolulu 

 Aquarium. One immature female and 5 males (retained by author) 

 found in bait well after loading Pranesus insularum (Jordan and 

 Evermann) at French Frigate Shoals (USFWS, JRM 31). 



Measueements. — (In mm) 5 females and 3 males: 



female male 



mean 

 Total length, excluding caudal setae 

 Length of cephalothorax, including 



frontal region 

 Width of cephalothorax 

 Length of genital segment 

 Width of genital segment 

 Length of abdomen 

 Length of caudal rami 

 Length of egg strings (2 strings) 



Description. — Female cephalothorax (fig. 62a) ovoid, consisting 

 of cephalon and first 4 thoracic segments. Frontal region approxi- 

 mately 15 percent of total length of cephalothorax, with broad mem- 

 brane along anterior margin and pair of lunules (fig. 63a) extending 

 posteriorly, on ventral surface, slightly past junction of frontal region 

 and rest of cephalothorax. Lateral margin of cephalothorax slightly 

 irregular, with fine membrane extending laterally and second mem- 

 brane extending medially, on ventral surface ; posterior lateral surface 

 with small but distinct concavity. Posterior sinus (fig. 62c) irregularly 

 U-shaped, with fine membrane along outer surface. Posterior me- 

 dian cephalothoracic region flatly convex, extending posteriorly well 

 past lateral cephalothoracic regions, connected to free fourth pedig- 

 erous segment by flaccid arthrodial membrane. Major dorsal ceph- 

 alothoracic grooves forming irregular H although anterior longitudinal 

 grooves of H extending posteriorly and medially, past cross groove 

 (more pronounced in female than in male) . Ocular region distinct, in 

 anterior third of cephalothorax. 



Female free fourth pedigerous segment narrow anteriorly, lateral 

 margins angled outward sharply to region of fourth leg attachment. 

 Segment indistinctly separable from genital segment. Genital seg- 

 ment (fig. 62c^) apple shaped, broader posteriorly, with fifth legs from 

 ventral-posterior lateral surface. Fifth legs (fig. 62/) consisting of 2 

 knobs, anteriormost with 1 plumose setule, posteriormost with 2, 



Female abdomen indistinctly separable from genital segment, con- 

 sisting of 1 or 2 segments. Indication of segment division indistinctly 

 present in middle of abdomen. Abdomen subrectangular, width ap- 

 proximately half the length, tapered slightly toward posterior end. 

 Posterior end angled sharply at attachment of caudal rami, anal region 

 bilobed. Caudal rami (fig. 62A) subrectangular, with smaU indenta- 



