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



not impossible that they may be sometimes reduced in number and become less con- 

 spicuous in various specimens, and this would render the resemblance between this species 

 and Aristeus armatus still greater. The carapace as well as the lateral walls of the 

 pleon are tomentose generally, which is a character of considerable importance, but the 

 pile is Ukely in old animals to be much rubbed off and therefore less noticeable. The 

 shortness and small diameter of the eye-stalk, and the comparative largeness of the eye 

 itself, which rests partially within a hollow thickly fringed with rather long hairs, is 

 another conspicuous feature. The first pair of antennae has the stylocerite waved, 

 strong, and scarcely reaching to the extremity of the first joint, which is armed at the 

 outer angle with a sharp tooth ; the second joint is a little shorter than the first, is sub- 

 cylindrical and covered all over with hairs ; the third joint supports a flagellum rather 

 shorter than in most species and attached near the base, while the other situated at the 

 extremity is longer. The latter was broken off in our specimen at a length about equal to 

 that of the entire animal, but, from comparison with other species, it was probably longer. 



The second pair is remarkable for the great length of the flagellum, about four times 

 that of the entire animal, and carries at its base a broad scaphocerite that is about as long- 

 as the peduncle of the first pair, extends inwards and dips between the antennae, 

 and partially encloses the last joints of the peduncle, which are rather long, reaching to 

 about two-thirds of the scaphocerite. The ancecerite or hook-like process is reduced to a 

 small rigid tubercle, but the phymacerite is prominent and horse-shoe-shaped. 



The epistoma projects forwards as a rounded pilose prominence, from which the 

 cheilogiossa projects downwards and overlaps the anterior margin of the mandibles, the 

 glossal portion filling the space between them. The mandible (d) is a strong and powerful 

 organ, and differs from that of the type only in the form of the synaphipod being more 

 pronounced, having the second joint nearly as long as the first, and carrying a strong 

 projecting process near the base ; both joints are thickly covered with long and stiff hairs. 



The metastoma is double and pear-shaped, overlaps the mandibles posteriorly and 

 reaches to the anterior lip. 



The first pair of siagnopoda has the first branch shorter and more quadrate, and the 

 second longer and more spinose. 



The succeeding pairs are very similar to those of Aristeus armatus. 



The first pair of gnathopoda is subpediform, very hirsute at the margins, and carries 

 an extremely long branch attached to the basisal joint ; the first joint of this branch is 

 very short and simple, the second is multiarticulate and fringed with numerous long 

 fine hairs. 



The second pair of gnathopoda is long, slender, and fringed with long stiff hairs, each 

 of which stands on its own protuberance on the inner and lower margin ; the dactylos 

 articulates with the propodos so as to attain a right angle only, at which degree two 

 bunches of small curved spinules on the opposed sides, one on the propodos and the 



