512 



BULLETIN 15 8, UNITED STATES NATIONAL MUSEUM 



Female. — Head short and wide and inclined dorsally at an angle 

 of 45° to the trunk axis; a narrow dorsal carapace divided length- 

 wise on the midline. Trunk pear shaped, narrowed into a long neck 

 anteriorly, swollen and depressed posteriorly; posterior processes 

 cylindrical, plump, and half as long as the ovisacs. First antennae 

 2-segmented; second antennae biramose, both rami 1-segmented, the 

 endoj)od larger than the exopod; second maxillae entirely separate, 

 two-fifths as long as the trunk, each enlarged at its tip into a crescent 

 or semicircle; maxillipeds with slender terminal claws. Total 

 length, 5.5-6 mm. 



Male. — Head conical, considerably swollen and gibbous posteriorly, 

 the mouth at the extreme anterior end and terminal, the part bearing 

 the second maxillae and maxillipeds near the posterior end and sepa- 

 rated from the rest of the head by a groove. Trunk distinctly 4-seg- 

 mented, the first two segments thoracic ; the third, the genital segment, 



FiGDEB 301. — Charopinus ticaudatus: a, Male, lateral; h, male, second antenna; c, 

 male, first maxilla ; d, male, second maxilla ; e, male, maxilliped 



somewhat enlarged, the fourth segment representing the abdomen 

 and bearing the caudal rami, each of which is conical with a single 

 apical seta. First antennae on the dorsal surface of the head near 

 the anterior end; each is 4-segmented and carries a single terminal 

 seta. Second antenna biramose, the exopod 2-segmented, the basal 

 segment twice the length of the distal, with a stout pointed process 

 on its inner margin. The end segment carries at its inner distal 

 corner a rigid curved claw, and at the outer corner a rounded knob 

 armed with stiff spines; between the two on the distal margin is a 

 small process tipped with a single seta. The endopod is clavate 

 and 1-segmented, the distal end with a fringe of short hairs, the 

 inner distal corner with a small process ending in a seta. The first 

 maxilla is 2-segmented, with three apical setae, the palp is replaced 

 by a single seta. The basal segments of the second maxillae are 

 fused across the midline, the terminal segments are free and each 

 has a slender apical claw. The maxillipeds are swollen into spheres, 

 with small apical claws shutting against a spiny plate on the side 

 of the sphere. Total length, 0.9-1.1 mm. 



