382 



MYSIDJS. 



the extremity of the last. The scale arises from the inner 

 and superior part of the first joint of the peduncle ; it is 

 hardly twice the length of the peduncle, slender, and taper- 

 ing very gradually to the extremity ; it is rather thinly 

 fringed. The upper surface of the peduncles of the supe- 

 rior antennae hollowed out, forming a bed for the eyes. A 

 short ovate scale arises from the inferior part of the last 

 joint, immediately below the origins of the setaceous por- 

 tions of the antennae. .A thick bunch of matted hair arises 

 from its extremity, which gives it the appearance of being 

 bi-articulated. The inferior edge of the external seta of 

 the superior antennae bears a thin fringe of very strong 

 hairs, which are thickest and strongest near the base. 

 The carapace is not large, leaving two of the thoracic seg- 

 ments exposed posteriorly ; it is rounded at its anterior 

 and inferior angle, and considerably produced at its inferior 

 and posterior angle. A strong bi-articulate and chelate 

 palpus arises from each side of the mouth. The abdomen 

 is slender, but the segments are not produced inferiorly. 

 The branchial subabdominal fins are five in number ; they 

 arise from all the abdominal segments except the last 

 [two]. The first, second, and fifth are like those in the 

 genus Mysis, namely, a single plumose joint ; the third and 

 fourth are pedunculated, the peduncles being composed 

 of two joints. The first joint is minute, the second is of 

 considerable length ; two branches arise from the extre- 

 mity of the second joint ; these branches, in the third fin, 

 are both plumose ; in the fourth one the internal only is 

 plumose. The external branch of the fourth consists of a 

 very long six-jointed spine, which reaches beyond the ex- 

 tremity of the caudal fins ; it is very finely pointed ; the 

 internal branch about the same as the first joint of the 

 external branch. The caudal plate is slightly swollen near 



