new Parasitic Gopepods on Fish. 97 



abdominal tubercle are two more processes, the dorsal being 

 the longer. 



Genital sac full of large round eggs. 



Length about 7 millira. without processes. 



Male minute, about 1 millim. long (PI. VI. fig. 2 e). 



Cephalothorax oval, distinctly divided off from the seg- 

 mented caudal portion, which appears to consist of three 

 joints, terminating in two lancinate plates. 



Anterior antennae placed close to the posterior, which spring 

 from the upper and anterior border of the cephalothorax ; 

 the first is three-jointed, ending in three short hairs ; the 

 posterior has a thickened basal joint and a short square second, 

 also terminating in three hairs. 



Fi?'st maxillipeds very large and strong, the root-joint very 

 muscular, its upper border being much lobed; the claw is 

 very strongly bent, thick at the base, and sharp at the point, 

 with a short curved tooth about the centre of the concave 

 border. 



EXPLANATION OF THE PLATES. 



Plate III. 



Fig. 1. Bomolochus denticulatus, J , sp. n., from the back, magnified. 



1 a. Seen from the side. 1 b. Hamulus anterior. 1 c. Terminal 



joint of posterior antennae. 1 d, e,f, (/, h. First to fifth 

 perseopods. 1 i. Last two joints of abdomen and caudal 

 plates. 1 k. Spur on outer side of outer branch of 

 perseopod, showing dentation, highly magnified. 

 Fig. 2. Hermilius longicornis, 2, sp. n., from back, magnified. 



2 a. Seen from the side, with valves closed. 2 b. Carapace 



seen from beneath. 2 c. Anterior antennae. 2 d. Ter- 

 minal joint of first maxilliped. 2 e. Third perseopod, 

 much magnified. 2/. Last joint of fourth peraeopod. 

 2 g. Abdomen and caudal plates. 



Plate IV. 



Fig. 1 . Caligus arii, $ , sp. n., enlarged, seen from the back. 



1 a. Carapace from underside, much magnified . 1 b. Third 



perseopod. 1 c. Fourth perseopod. 1 d. Abdomen and 

 caudal plates. 

 Fig. 2. Caligus platytarsis, $, sp. n., enlarged, seen from back. 



2 a. Fourth perseopod, hairy toe of same highly magnified. 



2 c. Fifth peraeopod. 2 d. Furcula. 2 e. Caudal plate. 

 Fig. 3. Caligus cossackii, 5, sp. n., seen from the back. 



3 a. Carapace from below. 3 b. Third peraBopod. 3 c. Fourth 



peraeopod. 3 d. Caudal plate. 3 e. Male, much enlarged. 

 3/. Second maxilliped of the same. 



