1380 THE VOYAGE OF H.M.S. CHALLENGER. 



multidenticulate crowu of the broad molar tubercle, with about five and twenty teeth in 

 each row ; on the left mandible there came into view a laminar edge which was finely 

 pectinate rather than dentate ; on the right mandible a row of fourteen projecting setules 

 was observed ; these minute details depend so much, as far as observation is concerned, 

 on the position of the mandible when mounted, that they cannot easily be made of 

 any service for specific characters ; the first two joints of the palp together longer 

 than the trunk, the first the thickest, about three-quarters the length of the second, the 

 second a little shorter than the third, which is slightly curved, apically acute, smooth 

 except for the adpressed cilia of the surface. 



First Maxilla}. — Basal joint broad, length and breadth about equal, the following 

 joint longer but less broad ; the outer plate more or less triangular, furred with setules 

 or spinules, and distally carrying a group of strong spines ; the palp broader and much 

 longer than the outer plate, with spinules along the inner border, two little spines at its 

 apex, and the apical border having a sort of mixed pectination and denticulation. 



Second Maxillie. — The inner plate shorter than the outer, each apically narrowed and 

 beset with spinules and setules. 



Maxillipcds. — The first joint or chin short, the following joint long and narrow, 

 longitudinally ridged on the inner surface, the ridge apparently ending in an apical 

 tubercle surmounted by a spine which does not rise above the outer rounded distal 

 margin of the joint ; the two outer plates have their bases close together within the distal 

 margin ; they are narrow, with four little spine-teeth on the serrate inner margin, one 

 such at the apex, and one just below it on the outer margin. 



First Gnathopods. — Shape of side-plates not discerned. First joint narrowly flask- 

 shaped, considerably longer than all the remainder of the limb ; second joint with a spine 

 at the hinder apex ; third joint very little longer than the second, with a longer apical 

 spine, the distal margin projecting a little behind the wrist ; the wrist distally much 

 wider than the hand, with a spine at the apex of the convex front margin, the straight 

 hind margin having one spine near the apex and two at the apex, which is produced so 

 as to clasp the base of the hand and is pectinate on its inner edge ; the hand a little 

 shorter than the produced wrist, having much of the nearly straight hind margin 

 pectinate, the front margin carrying on the distal half two spines and an apical spinule ; 

 the finger curved, not half the length of the hand, finely pectinate on the inner edge. 



Second Gnathopods. — The first joint rather longer than in the first gnathopods and 

 its front straighter, the remaining joints very similar to those of the preceding pair, but 

 all rather larger, the wrist more strongly produced and more decidedly longer than the 

 hand. 



First Perseop>ods. — The side-plates as in the other segments small and with the upper 

 boundary very faintly marked. The branchial vesicles large. The first joint rather 

 larger than in the second gnathopods, longer than the three following joints together, 



