296 THE VOYAGE OF II. M.S. CHALLENGER. 



The second pair of antennae (fig. 3, c) carries a triangular scaphocerite, that is stiff 

 and rigid on the outer side and deeply cleft at the extremity by a long slit between the 

 spine and the foliaceous portion. The terminal joint of the peduncle extends to about 

 half the length of the scaphocerite, and in this respect differs from Milne-Edwards' 

 description, wherein he says that it " nearly reaches the extremity of the scale which 

 covers it." The flagellum is slightly compressed, and its length is about half that of 

 the animal, and the phymacerite is implanted on the inner side. 



The mandibles are large and very robust ; the psalisiform margin is smooth and 

 connected with a large, smooth, molar disc, and carries a strong foliaceous, two-jointed 

 synaphipod. 



The first pair of siagnopoda is three-branched, and resembles that of the genus 

 Gennadas rather than the true Penseus. 



The second pair of siagnopoda very closely resembles that of Penseus, differing only 

 in having the first branch with its two foliaceous plates smaller. 



The third pair of siagnopoda differs from that of Penseus in having the central 

 branches shorter. 



The first pair of gnathopoda resembles that of Penseus in the manner in which the 

 terminal three joints are reflexed upon the inner and under surface, but differs in having 

 the meral joint so thin and broad that it overlies and covers the terminal joints. The 

 coxa carries a long and slender mastigobranchia shaped like that in Penseus, and, as in 

 that genus, there is no branchial plume attached to it, and not even the rudiment of any 

 basecphysis — an appendage that is so generally present in the Penaeidea. 



The second pair of gnathopoda is long, slender, and pediform ; it carries no basec- 

 physis and terminates in a dactylos that is oval and spatuliform. The mastigobranchia 

 appears to be absent from this limb, also one of the arthrobranchia and the pleuro- 

 branchial plume. 



The anterior three pairs of pereiopoda are chelate and carry no branch on the basisal 

 joint, but a long and forked mastigobranchia, similar to those of Penseus, and two arthro- 

 branchia! plumes. The posterior two pairs are short, stout, and simple, and have 

 neither branch, branchial lash, nor plume. 



The ventral surface in our male specimen is furnished with a long and formidable 

 styliform tooth, that originates on the penultimate somite of the pereion and reaches 

 as far forwards as the coxa of the second gnathopod. In the female a similar broad-based 

 ventral tooth exists, and behind it is a broad plate connected with the posterior somite 

 of the pereion, and passing back to the posterior margin of the pereion. 



The first pair of pleopoda carries a longitudinally folded petasma that meets its 

 corresponding fellow and unites with it by several small hooks, and on the second pair 

 is a second petasmiform appendage that terminates in a condyloid extremity, but does not 

 unite in the median line. All, the other pleopoda are single-branched, except the posterior 



