82 G. 0. SARS. CRUSTACEA. [norw. pol. exp. 



The posterior maxillipeds (fig. 4) are rather slender, though scarcely longer 

 than the very strongly built anterior maxillipeds. The 1st basal joint is com- 

 paratively short and somewhat lamellar, carrying at the end anteriorly a short 

 spine accompanied by a small bristle. From about the middle of the anterior 

 edge another much larger spine, or more properly seta, of a peculiar, compact 

 consistency originates. This seta, which is unciliated and somewhat flexuous, 

 is comparatively longer than in the type species, and gradually tapers to a 

 fine point. The 2nd basal joint is very slender, and carries anteriorly 5 setae, 

 the outer 2 issuing from a particular lobe at the junction with the terminal 

 part. The latter is shorter than the 2nd basal joint, and is composed of 5 

 articulations rapidly diminishing in size, and carrying comparatively short 

 bristles. 



The legs, as in the other species of this genus, are all natatory, with 

 both rami distinctly 3-articulate. In structure they agree, on the whole, with 

 those in H. spinifrons, the terminal joint of the outer ramus in the 2nd, 3rd 

 and 4th pairs being distinguished by its large size and foliaceous character. 



The 5th pair of legs (fig. 5) are considerably smaller than the next 

 preceding ones, and are distinguished by the strong spine issuing from inside 

 the 2nd joint of the outer ramus. In the present species this spine is shorter 

 than the terminal joint, is somewhat cultriform, and stands out from the joint 

 at nearly a right angle. 



The adult male (fig. 6) is a little smaller than the female, scarcely 

 exceeding a length of 4-20 mm. It is easily recognized by its more slender 

 form, the different structure of the tail, and the geniculate left anterior 

 antenna. The form of the anterior division of the body is about the same 

 as in the female, except that the last segment is more distinctly defined from 

 the preceding one. The tail is very narrow, cylindric, and composed of 5 

 well-defined segments, none of which is protuberant below. The caudal rami 

 with their setae are exactly as in the female. 



The left anterior antenna (see fig. 6) is somewhat shorter than the right, 

 and has a very distinct geniculation at about the distal 3rd part of its length. 

 The articulations preceding this geniculation are, however, but very slightly 

 dilated, and the movable terminal part is quite simple, consisting of 5 slender 

 articulations. 



