68 BRITISH PARASITIC COPEPODA. 



of the carapace, width about three fourths of the 

 length, lateral margins only slightly arcuate. Abdomen 

 short, composed of a single segment ; caudal rami 

 short and bearing a few apical setae. 



Antennules small. Antennas short and moderately 

 robust, and armed with a stout sinuately-curved 

 terminal hook. Mandibles slender but scarcely so 

 much so as in Lepeophtheirus nordmanni. Second 

 maxillipeds stout and provided with short but strong 

 terminal claws. The sternal fork with the basal part 

 somewhat expanded, the rami short, tolerably broad 

 and divergent, each ramus truncated at the end and 

 split into two portions by a longitudinal sinus, the 

 inner portion being much narrower than the outer. 

 Fourth pair of thoracic legs tolerably elongated, basal 

 joint stout, ramus composed of three joints, the 

 middle one being rather longer than the first or third ; 

 the outer distal angle of the first joint ending in a 

 bluntly-rounded knob, the second joint bearing a short 

 spine on its outer distal angle, and the end joint three 

 terminal spines, the innermost of the three spines being 

 longer than the others and finely serrate along the 

 outer margin. The fifth pair very small and rudimen- 

 tary. Length about half an inch (12*5 mm.), but 

 varying somewhat in different specimens. Egg-strings 

 slender and elongated. 



Male. Carapace orbicular, as long as broad, and 

 equal to about two-thirds of the entire length of the 

 animal. Free thoracic segment very small, and 

 slightly produced on each side. Genital segment very 

 small, with a pair of minute setiferous processes on 

 each side at the postero-lateral corners. Length about 

 6'5 mm. 



Habitat. Parasitic on the backs of large halibut, 

 Hippoglossus vulgaris Fleming. Berwick Bay (Dr. 

 Johnston). Polperro, Cornwall (A. M. Norman). 

 Aberdeen (T. Scott). Shetland (C. B. Wilson). 



Distribution. North Sea; Greenland, Iceland, 

 Massachusetts (Cape Ann), U.S.A. 



