182 THE VOYAGE OF H.M.S. CHALLENGER. 



carapace, armed on each side with two long teeth, and with a row of smaller ones that 

 diverge and terminate over the gastric region. A prominent tooth is placed above 

 the orbit, and another above the infero-anterior angle of the carapace, and the general 

 surface is slightly papillose. 



The pleon is scarcely as long as the carapace including the rostrum, it is dorsally 

 smooth, and the coxal plates are produced to a sharp point, the anterior margin of each 

 of the four anterior being armed with a sharp tooth near the base. The eyes are small 

 and immature. 



The first pair of antennse has the peduncle half the length of the rostrum, and the 

 flagella reaching about half as far beyond it : the first joint of the peduncle or coxa has 

 an enlargement on the upper and outer surface enclosing the auditory apparatus. 



The second pair of antennas has lost the flagellum, 1 the peduncle is as long 

 as that of the first pair, and articulates with, but is not anchylosed to the metope. 

 The coxal joint is short and carries on the inferior surface a phymacerite, which 

 is formed by a prolongation of the external tissue, and has its apex covered by a 

 thin membrane, in which an elongated perforation exists ; the succeeding joints, 

 which form the peduncle, reach to the extremity of that of the first pair, or to 

 about the middle of the rostrum, or as far as the anterior pair of teeth on its upper 

 surface. 



The siagnos, or mandible, has a smooth, cutting margin, and a strong molar ridge, 

 and in the hollow between the two ridges the three-jointed synaphipod lies when at rest ; 

 the distal joint of the latter is the longest, and is fringed on the outer margin with 

 short, strong, bristle-like hairs. 



The first pair of siagnopoda (PL XXIII. fig. 3e) consists of two small foliaceous plates 

 fringed on the distal margin with short, stiff, spine-like hairs, and on the inner margin 

 with a few longer that are ciliated, and a robust basecphysis terminating in a long 

 reversed lash, which probably ends in two long sweeping hairs, but the part is broken in 

 our unique specimen ; at the base of this branch is a large fasciculus of ciliated hairs. 

 This appendage differs from the same in Nephropsis rosea in having the large foliaceous 

 plate broader at the distal extremity, and the basecphysis less slender and fringed with 

 fewer hairs, but has a larger fasciculus at the base externally. 



The second pair resembles that of Nephropsis rosea, but has the several foliaceous 

 rami slightly broader, and the mastigobranchia produced somewhat more posteriorly. 



The third pair closely resembles that of Nephropsis rosea, and so also does the first 

 and second pairs of gnathopoda. 



The first pair of pereiopoda is somewhat more slender, and has the dactylos and 



1 Dr. v. Willenioes-Suhm remarks in his notes on this species, " Also with this well-preserved specimen, every trace 

 of the outer antennal lash is wanting, as in the specimen from Bermuda, so that I must now suppose that they are 

 normally wanting ;" an opinion which we cannot accept, as Mr. Wood-Mason has figured it in his species of Nephropsis 

 stewarti, and it exists in the North Atlantic species. 



