neio Parasitic Copepods on Fish. 11 



antennce sis- or seven-jointed, first joint broad, second elon- 

 gate, with fine hairs at the base and a lobe-like process from 

 the front border equalling in length the segment, third joint 

 with three fine hairs, fourth with two, fifth and sixth with 

 two, and terminal joint with seven bristles. Poaterior an- 

 tennce three-jointed, last in the form of a strong hook, with a 

 well-marked tooth on the concave border near the centre. 

 Bosirum in the form of a short strong chitinous tube. Max- 

 illary palp three-jointed, the last joint being sharp and curved. 

 Fivfit maxilliped three-jointed, the basal joint being thick and 

 muscular, the second cylindrical, the furthest end of the inner 

 border being finely dentate ; last joint short, sharp, curved, and 

 dentate on concave border. Second maxilliped two-jointed, 

 the basal joint being of very great size and muscular, its 

 lower margin undulate and fringed with bunches of fine hairs ; 

 second joint in form of a strong curved elavr, the internal 

 border being armed with a strong tooth. Thorax three-partite, 

 the first segment having a soft lateral rounded appendage on 

 either side, those of the next two segments beins: longer : 

 under the first is seen a small plate with edge finely ciliated, 

 giving off the rudimentary first two-branched perseopod, the 

 outer an oval single-jointed limb terminating in one minute 

 hook and two short hairs ; the inner branch is shorter and 

 carries three minute hairs. Under the second appendage is 

 another plate carrying a single-jointed limb, terminating in a 

 small hook, and the inner edge being provided with many 

 fine hairs. Behind the third appendage, springing from the 

 anterior portion of the genital segment, is a minute stump, 

 from the apex of which is a single bristle. 



Genital segment constricted in front, twice as long as 

 head and thorax, indistinctly lobed at the posterior extre- 

 mity. Two elongate foliaceous caudal plates. Egg-sacs 

 long, thin. 



Male (PI. V. fig. 2). — Body shorter, head more oval. Pos- 

 terior antennce longer than in the female ; no thoracic ap- 

 pendages. Maxillipeds are also less robust, but very long 

 and powerful. The rostrum is longer, and on either side of 

 the lower lip is a sharp, slightly curved, very long, articulate 

 movable process directed directly backwards, equalling about 

 half the length of the head. 



Both terminal joints of first perseopods have compara- 

 tively strong claws — in fact, these paired limbs are more 

 developed in the male. Genital segment elongate, ta|)ering 

 posteriorly, where a rounded abdominal portion is distinctly 

 marked off, carrying two caudal foliate appendages, the 

 extremity being fringed with fine hairs. 



