1058 THE VOYAGE OF H.M.S. CHALLENGER. 



flagellum of the upper antennae, slender, with thirty-eight joints, of which the last is 

 much shorter and narrower than the one preceding it. 



Upper Lip not observed with sufficient distinctness for description. 



Mandibles. — In the left mandible, which is drawn on the right hand of the Plate, the 

 principal and secondary plates have each a border of four not very unequal teeth ; on the 

 right mandible the principal plate appears to have four or five teeth, the lowest being the 

 longest, while the secondary plate is almost spine-like, having one prominent denticle on 

 the side, while the denticles of the apical part are adpressed ; the spine-row is of eight 

 broad curved spines, which apically have a minutely furcate appearance, three spinules 

 projecting between the longer front and shorter hind branch of the fork ; the molar 

 tubercle is prominent, with a lateral tooth on the forward side, and the crown bordered 

 with comparatively few but broad denticles ; the first joint of the massive palp is short 

 but broad, widest distally ; the second joint seems quite disproportionate to the trunk of 

 the mandible, long, and of great breadth, its greatest breadth being nearer the base than 

 the apex ; it has slender spines at eight points on the front margin, and a few near the 

 apex on the other ; the third joint is of nearly the same length but much narrower, 

 the outer margin convex, the inner carrying eight slender spines on its distal half, and 

 two or three on the apex. 



Lower Lip compact ; the principal lobes broad and deep, ciliated on the inner 

 margins and the inner part of the broadly convex distal margin ; the inner lobes 

 narrowly oval ; the mandibular processes very little prominent. 



The First and Second Maxillae, so far as could be observed, are very like those of the 

 preceding species ; the inner plate of the first maxillae apparently without setae, the 

 second joint of the palp having four spine-teeth on the dentate apical margin, besides 

 slender subapical spines; the maxillipeds were . not observed, having probably been lost 

 during the dissection of the minute mouth-organs of this species. 



First Gnathopods. — The side-plates directed forwards so as to cover the basal joints 

 of the upper antennas, much wider below than above, the hind margin produced into an 

 apical tooth, between which and the very convex lower margin no interval is left; the 

 fringe of the lower margin is not greatly developed. The first joint not reaching to the 

 end of the side-plate, expanding a little distally, carrying six long setae on the lower 

 convex part of the front margin, three on the surface above the centre, five on the hind 

 margin below it ; the second joint not longer than broad, with five plumose setae at the 

 hinder apex ; the third joint with a few spines on the hind margin and two large 

 transverse groups on the inner surface at an angle with the oblique distal margin ; the 

 wrist rather broad, with many spines along the hind margin and on the inner surface near 

 it, and a few spines near the front margin ; the hand not very much shorter than the wrist, 

 with spines at four points of the slightly convex front margin, besides the larger apical 

 group ; the hind margin is sinuous, bordered with spines of various lengths except for a 



