392 THE VOYAGE OF H.M.S. CHALLENGES. 



ciliated hairs, which are articulated at the base on small bulbous prominences ; the outer 

 margin is straight, free from hairs, and produced to a short tooth at the distal extremity. 



The mandible (d) is small but robust ; the incisive margin is concave, smooth, and 

 projects anteriorly and posteriorly into a sharp tooth; it carries a two-jointed synaphipod, 

 the basal joint being long and narrow, and the distal one about half the length of the 

 first and somewhat narrow. 



The oral appendages exhibit nothing very distinguishable from those of other species ; 

 the first pair of siagnopoda or maxillae (e) consists of three plates ; the inner is broad, 

 foliaceous and armed with small spine-like hairs ; the median is broad, becoming 

 broader at the distal extremity, and is furnished with small robust spines on the inner 

 margin and with a few hairs on the distal ; the outer plate is small and rudimentary and 

 tipped with only two hairs. 



The second siagnopod (f) consists of four foliaceous rami and a broad mastigo- 

 branchial plate. The three inner are foliaceous, broad at the distal extremity, and 

 fringed with stiff hairs ; the central plate is subfoliaceous, and appears to be homolo- 

 gous with the typical appendage ; it is narrow, somewhat robust, shorter than the 

 other plates, and is tipped with three strong teeth or spines. The mastigobranchia is 

 foliaceous and of extreme tenuity ; it reaches forwards in advance of or to the same 

 level as the distal extremity of the other plates, and expands posteriorly into a broad 

 and extended plate, fringed all round with cilia that radiate at right angles to the curved 

 margin. 



The third siagnopod (g) or first maxillipede consists of two foliaceous plates and one 

 triarticulate, cylindrical branch ; the inner plate is long, broad, and of nearly the same 

 breadth to the extremity, which is rounded ; the inner margin is fringed with hairs and 

 the outer smooth. The outer foliaceous plate appears to spring from the same base 

 as the inner ; it is also subequally broad to the rounded extremity, excej)t upon the 

 inner side near the base, where the triarticulate branch originates ; this latter branch is 

 cylindrical, or nearly so,, and reaches a little beyond the two plates. Attached to the 

 coxal joint by a small pedicle is a broad, smooth-margined, membranous, mastigo- 

 branchial appendage. 



The first pair of gnathopoda is only six-jointed. The coxa is short and thick, the 

 two succeeding joints are long, cylindrical and subequal, the next two are genuflexed upon 

 the two preceding ; all the joints are fringed with small fine hairs on the lower and outer 

 side, and the terminal joint, which is broad, flat, and truncated, has the distal margin 

 fringed with hairs. 



The second pair of gnathopoda is much longer than the first, and consists of six joints, 

 which gradually diminish in size as they succeed each other, the distal joint being strongly 

 fringed with hairs. 



The first pair of pereiopoda is slender, feeble, and shorter than the second pair of 



