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



consideral:)ly longer than any of the others ; one or two of the terminal joints apparently 

 missing. 



Upper Lip with the distal margin nnsymmetrically bilobed. 



Mandibles. — ^The cutting edge in one of the mandibles with four small denticles at 

 the top and five larger ones below, in the other mandible with four small denticles 

 above and four below, and three larger in the centre ; the secondary plate and spine-row 

 not clearly made out ; the palp as in Metopa magellanica. 



Lower Lip, Maxillse, and Maxillipeds similar to those of Metopa magellanica, but in 

 the present species, the first joint of the maxillipeds is much larger m jDroportion to the 

 second joint than in the species just mentioned. 



First (?nai/iopocZs.— Side-plates small, almost concealed by the following pair, broader 

 above than below, with two spinules on the lower part of the front margin. The first 

 joint attached at the lower end of the side-plate, fringed with setae on both margins, 

 a little widened distally, not equal in length to the hand and wrist united ; the second, 

 third, and fourth joints much as in Metopa magellanica, but the third joint, of which 

 the lower part is furred, is broader in proportion to its length, while the wrist is 

 narrower ; the apical spines of the third joint are six in number, of which one is short, 

 two are much longer, slender, geniculate, with accessory threads, and the other three 

 are of unequal size but all feathered ; there is similar variety in the spines on the hind 

 margin and apex of the wrist, which is almost as long as the hand and rather broader, 

 and has several spines on the surface ; the hand resembles in armature that in Metopa 

 magellanica, except that its palm-margin is finely crenulate instead of pectinate, the hind 

 margin is longer and the palm proportionately shorter than in that species ; the finger is 

 finely pectinate on the inner margin, which forms a small denticle at the base of the nail, 

 where there are two cilia, of which three more are spaced along the margin. 



Second Gnathopods. — Side-plates tending to a semicircular form, but wdth the lower 

 j)art much broader than the upper. Branchial vesicles as in Metopa magellanica. The 

 marsupial plates long and broad. The first joint reaching beyond the side-plate, as long 

 as the wrist and hand united, with setse on the margins ; the second joint short, with 

 setae at two points of the hind margin ; the third joint as long as the short wrist, with 

 setules at one or two points of the hind margin and a group of slender spines at its blunt, 

 apex ; the wrist as in the preceding species ; the hand broad, the front margin not twice 

 as long as the hinder, which has setules at four points and is apically produced into a 

 sharp tooth defining the palm ; within this process are set two palmar spines, between 

 which the nail of the very broad finger closes down against the process ; the palm-border 

 is crenulate in two divisions and fringed with spinules or setules ; the inner margin of 

 the finger is smooth, and much less convex than the outer ; it has a dorsal cilium near 

 the hinge and cilia at the base of the nail. 



First Perieopods. — Side-plates broader below than above, front and hind margins 



