new Parasitic CopepoJs on Fish. 85 



quite squarely with the abdomen; at the outer angle on 

 either side one sees a small process carrying three fine hairs 

 (rudimentary fifth perseopods), also a longer one placed just 

 internal to it. Abdomen single-jointed, long, equal in length 

 to that of the last segment of the cephalothorax and the 

 genital one. Caudal plates much longer than broad, on a 

 narrow base, carrying three long plumose hairs posteriorly — 

 a shorter one on the inner border and two minute ones on the 

 outer. 



Length 6 millim. 



Caligus Cossackii, sp. n. (PI. IV. fig. 3.) 



This species was taken from the gill-cavities of Chryso- 

 phorys sarba at Bunder Abbas, in the Persian Gulf, in some 

 quantity, both sexes; the male had also been taken before 

 from the same fish at Colombo, together with a second unde- 

 termined species and Lernanthropus atrox. 



These were very active, living for some time in a glass 

 tube, showing great fondness for creeping up the glass out of 

 the water, as Dana described, when they were with difficulty 

 dislodged, at other times swimming briskly about ; during 

 life the genital segment showed a very corrugated edge and 

 the intestine was clearly seen to pass down to the extremity 

 of the abdomen between the caudal plates. 



This species bears a considerable resemblance to C. pro- 

 ductus of Steen. & Liitk., which varies considerably from the 

 C. productus of Kroyer *, but is differentiated from them 

 both by the character of the hamulus anterior, first peraeopods, 

 and by the caudal plates, &c. 



Female. — Cephalothorax oval, much longer than broad, 

 equal to one half the total length ; frontal plate deeply exca- 

 vated in the centre, having on the outer portion the very large 

 and prominent lunulas which extend to the back border of 

 the plate. Anterior antennae : first joint not quite so long as 

 the breadth of the lunule ; it is provided with about seventeen 

 plumose hairs, these being longest at the outer end ; second 

 joint of moderate length. Posterior antennai terminating in 

 a very slender hook. Hamulus anterior very large, with a 

 widely dilated base and a strongly recurved blunt hook. 

 First maxilliped of usual form, the second having a short 

 thick basal joint and a moderately large terminal claw with a 

 minute hair on the concave border. 



Furcula with a narrow base, giving off two pointed diver- 

 gent branches, which again approach towards the extremity, 



* ' Bidrag til Kuudskab,' 1803, pp. 64-6U. 



