HATSCHEKIA HIPPOGLOSSI. 113 



than the length, sides rounded. Between the cephalon 

 and the genital segment is a short neck, narrow and 

 indistinctly segmented, and provided with rounded 

 lobes on each side. Genital segment considerably 

 elongated and rather narrow, its width scarcely equal 

 to one-fourth of the length, and with the postero- 

 lateral corners produced into rounded lobes about 

 equal in size to the small abdomen that is intermediate 

 between them and which is also rounded ; the pos- 

 terior end has thus a trilobed appearance. Caudal 

 rami extremely small. 



Antennules short, rather stout, and composed of 

 five small joints which are sparingly setiferous. 

 Antennae tolerably large and armed with strong 

 terminal hooks and with a small appendage at the 

 base. Mandibles small, elongated, tapering distally, 

 and provided with a few small teeth at the distal 

 end of the inner margin. Maxilla? very small but 

 comparatively stout, and furnished with two or three 

 tooth-like processes. Maxillipeds elongated and 

 slender. Thoracic legs two pairs, short and biramose, 

 both rami appearing to be composed of two somewhat 

 indistinct joints. Length about 9 mm. ; length of head 

 and neck combined 1*5 mm. Egg-strings long and 

 slender. Colour resembling that of the gills to which 

 the parasite was adhering. 



Male. The male is much smaller than the female 

 but has a general resemblance to it. The cephalon is 

 proportionally rather larger and the thoracic ring is 

 distinctly segmented. The genital segment is also 

 proportionally much shorter than in the female, being 

 only about twice as long as broad. 



Antennules short, composed of five joints. Antennas 

 provided with large and strong hooks, projecting well 

 in front of the cephalon. Caudal rami narrow and 

 more prominent than in the female. Length 1*5 mm. 



Habitat. Parasitic on the gills of halibut, Hi}>j><>- 

 glossus vulgaru ; not uncommon. The reddish 

 coloured, thread-like egg-strings may sometimes be 



VOL. I. 8 



