72 BRITISH PARASITIC COPEPODA. 



Maxillas short and stout, and with the extremity dis- 

 tinctly bifurcated. Second maxillipeds robust and 

 armed with short and stout terminal claws. Basal 

 portion of the sternal fork short, the rami also short, 

 somewhat expanded and bluntly rounded at the tip ; 

 slightly divergent and separated from each other by a 

 comparatively wide semicircular space. The fourth 

 pair of thoracic legs somewhat like those of Lepeoph- 

 theirus hippoglossi, but rather more robust, the first 

 joint of the ramus, which is rather longer than the 

 second or third, with the outer distal angle in the form 

 of a blunt knob covered with microscopic bristles, the 

 second joint provided with a short spine on the outer 

 distal angle, and the third with three spiniform apical 

 setae, the inner one being the longest. Egg-strings 

 very long and slender. Length 14-16 mm. 



Male. The carapace of the male is rather longer 

 than broad and more than half the entire length of 

 the animal. Frontal plates narrow. Free thoracic 

 segment of moderate size, its length rather less than the 

 width. Genital segment ovate, longer than broad, and 

 equal to about one-third of the length of the carapace. 

 Abdomen rather narrower than the genital segment, 

 and about a third shorter. Caudal rami about half as 

 long as the abdomen. 



The thoracic appendages are somewhat similar to 

 those of the female, except that the second maxillipeds 

 are proportionally stronger. Length 6-7 mm. 



Habitat. Parasitic chiefly on salmon, Salmo salar, 

 L., but it also occurs on one or two other species of 

 the Salmonidas. Berwick (Dr. Johnston). Ireland 

 (W. Thompson). Polperro, Cornwall (A. M. Norman). 

 Plymouth ( Bassett- Smith). Scottish coasts (T. Scott). 

 Irish Sea (A. Scott). 



This is one of the more widely distributed of the Caligidse. 

 It is recorded from the coasts of Alaska, Labrador, and 

 from other parts of the North American sea-board, as well as 

 from the coasts of Europe. The parasite does not appear to 

 survive long after the fish enters the fresh water. The dorsal 

 surface in this species has a curious metallic lustre different 



