atifj on Six Netv Specks of Ctmfacea, ^c. 177 



first joint of the peduncle ; it is hardly twice the length of the pedun- 

 cle, slender, and tapering very gradually to the extremity ; it is rather 

 thinly fringed. The upper surface of the peduncles of the superior an- 

 tenncD 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 portions of the antennae. A thick bunch of 

 matted hair arises from its extremity, which gives it the appearance of 

 being biarticulated. The inferior edge of the external seta of the su- 

 perior autennte bears a thin fringe of very strong hairs, which are 

 thickest and strongest near the base. The carapace is not large, leav- 

 ing two of the thoracic segments exposed posteriorly ; it is rounded at 

 its anterior and inferior angle, and considerably produced at its inferior 

 and posterior angle. A strong biarticulate and chelate palpus arises 

 from each side of the mouth. The abdomen is slender, but the seg- 

 ments arc not produced inferiorly. The branchial subabdoniinal fins 

 are five in number ; they arise from the inferior and posterior angle of 

 all the abdominal segments except the last. The first, second, and 

 fifth arc like those in the genus mysis, viz., 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 extremity of the second joint ; 

 these branches, m the third fin, are both plumose ; in the fourth one, 

 the internal only is plumose. The external branch of the fourth con- 

 sists of a very long six -jointed spine, which reaches beyond the extre- 

 mity of the caudal fins ; it is very finelj' pointed ; the internal branch 

 about the same as the first joint of the external branch. The caudal 

 plate is slightly swollen near the base; its edges are serrated, and its 

 extremity' bifurcated ; the bottom of the fork being rounded, and the 

 extremities of the fork also blunted and rounded. The internal caudal 

 fins are truncated at their extremities ; the external are paddle-shaped, 

 and rounded at their extremities. Both of these fins are fringed at 

 their extremities, and inferior edges with long hairs. 



Fig. 9. PI. II. 

 T, Brevi spinosa, — Superior antennal scale not so long as the peduncle ; 

 inferior antennal scale four or five times as long as the peduncle. In- 

 ternal branch of the third subabdominal fin minute ; the internal 

 branch of the fourth longer than the first joint of the external branch ; 

 the external branch extending a little beyond the base of the caudal 

 fins, ending by means of a dart-like point. The lateral caudal fin 

 ending in a sharp point superiorly, and rounded inferiorly ; the inter- 

 nal fin oblong, ovate, and pointed. The lateral edges of the middle 

 plate bearing a single row of long, sharp, and bent spines ; contracted 

 near the base and the bottom of the fork, forming an acute angle ; 

 prongs pointed. 

 VOt. XXXIir. NO, LXV.-— 7VLY 1842. If 



