101 4 CRUSTACEA. 



fourth pairs of feet ; /, last segment of abdomen, under view ; g, one 

 of first pair of stylets. 



Atlantic, latitude 4° 25' south, longitude 21° 30' west. Collected, 

 November 7, 1838, 4 A. m. 



Length, when extended, one-fourth of an inch ; when folded up, 

 one-eighth of an inch. Nearly colourless ; diaphanous. Head large 

 and broad, the whole covered with facets, excepting a small space in 

 front. Within, four small black spots of pigment, the two outer of 

 which are transversely oblong, and the two inner (between the outer) 

 are acute-triangular, and longitudinal in position. Lower surface of 

 head nearly all open, the antennary area being much broader than 

 long ; at the centre of its anterior margin, there is a slight triangular 

 projection. Thorax broad, broadest posteriorly, seven-jointed; epi- 

 merals distinct. Abdomen about as long as head and thorax together. 

 The last segment has no suture separating a seventh normal segment 

 from sixth ; but a faint one is observed separating the fifth and sixth. 

 The last pair of stylets is articulated with the under surface, and 

 extends backward as far as extremity of abdomen. The second pair 

 reaches to base of third pair. The inner antennae have the last joint 

 of base crossed by fine lines (10 ?) indicating articulations, and the 

 surface is short hairy; the preceding joint is equally stout, of nearly the 

 same length, but is at right angles with the last. The first joint 

 of the appendage is the largest of the three. Coxa of sixth pair with 

 the outline sparingly undulate, being concave for the most part on the 

 anterior side ; rest of leg slender and short, and articulated on medial 

 line of coxa farther than its length from the apex. The posterior sty- 

 lets have a very short base, and subequal lanceolate branches. 



Observed a palpitating longitudinal vessel (shown in fig. 4 b), situ- 

 ated in the third, fourth, fifth, and sixth thoracic segments. 



Abdomen is generally applied to the venter, and, in connexion 

 with the clypeate coxse, it covers the whole of the ventral surface, 

 including the antennary cavity. 



[The first pair of legs was not made out.] 



