new Parasitic Copepods on Fish. 95 



Pseudoclavella ovalis, sp. n. (PI. VI. fig. 1.) 



The gills of a Serranus, sp., captured at Muscat, were 

 found to be crowded with these small parasites, which held 

 very firmly on to the delicate margins of the gills by their 

 strong posterior antennas ; the long dark-coloured ovarian 

 tubes projecting considerably outwards made their detection 

 easy ; altogether there were hundreds of them in the one fish. 

 Female. — Caput of an oval shape, with a slight central 

 lobe anteriorly, and somewhat broadened behin 1, where it 

 unites with the single free thoracic segment, which is broader 

 than long. The genital segment is of an elongated oval 

 shape, robust in form, about four times as long as the cephalo- 

 thorax. Abdominal segment small, broader than long, giving 

 off two foliate caudal plates, each bearing three short, fine, 

 terminal hairs and a fourth of smaller size on the outer 

 border ; on each side of tiie abdominal tubercle are seen the 

 comparatively large egg-tubes filled with large flattened 

 ovules in a single row. 



Anterior antenna} rise from the head a little behind the 

 anterior border ; they appear to be three-jointed, but the 

 divisions are very indistinct; from the basal joint, which is 

 long and thickened, rise two pairs of short strong hairs on 

 the front border ; from the second, which is shorter, there are 

 two short hairs above and one below; the last joint, which 

 is longer, bears two short hairs near the base, one above and 

 one below ; a very long, strong, deeply rooted one on the 

 upper border near the middle, with a tuft of smaller terminal 

 bristles. 



Posterior antenna? placed a little further back ; it is two- 

 jointed, the first being broad and stout, the second in the 

 form of a strong, short, recurved, claw, with a thickened 

 tuberculate base ; this does not project beyond the cephalic 

 border. 



Rostrum short, blunt. Palp very minute, slender, straight. 

 Outside this is seen a very small representative of the first 

 maxilliped ; it is three-jointed, the terminal joint in the form 

 of a claw. 



Second maxilliped large, the extremity of the basal joint 

 projecting well beyond the border of the head ; the second 

 joint is very slender, longer than the basal, terminating in a 

 curved sharp point. 



Rising from the posterior border of the carapace on either 

 side underneath are seen the first pair of thoracic limbs ; 

 there is a broad basal joint, giving off two small branches, 

 the inner is single-jointed, terminating in two hairs, the outer 



8* 



