M Y S I D E A. 675 



segment, and the two separated by a suture. Abdomen extremely 

 slender; first five segments subequal, sixth much longer, and con- 

 stricted laterally just anterior to middle. Caudal segment truncate 

 at apex ; four apical spinules observed, and four lateral, the anterior 

 of the lateral about one-third the distance from the base to the apex. 

 Caudal lamellae subequal, and scarcely longer than caudal segment; 

 the outer having a spine at the outer apex, the inner obtuse, both 

 slender. In a lateral view (fig. 3ft), the sixth abdominal segment is 

 seen to have two short spines below near the extremity, and one at 

 the superior apex. 



The eyes give green internal reflections. Antennae in the specimen 

 possibly mutilated ; first pair consists of four slender joints, first longer 

 than the eyes, the second and third about equal, and each more than 

 one-fourth the first, the last nearly as long as the first. This last 

 joint may correspond to the flagellum, which, as the individual was 

 quite small, might not have been wholly developed. The outer an- 

 tennae have a flagellum ; the basal scale is slender oblong, longer than 

 the eyes. The posterior legs have a rudimentary palpus at base 

 (fig. d). 



APPENDIX TO THE MYSIDEA. 

 GENUS FURCILIA. 



Carapax aut breviter rostratus aut fronte truncatus. Oculi breves, 

 symmetrici, aperti. Antennae internee bifidce, basi elongate, articulo 

 primo longo et ad apicem inferiorem longe" producto, processu intus sub- 

 tilissime' spinuloso. Antennae externce lamind basali carentes. Abdo- 

 minis pedes natatorii; segmentum posticum truncatum apice barbis non 

 ornatum, spinulis scepius armatum. Branchiae nullce. 



Carapax either short beaked, or truncate in front. Eyes short, sym- 



