1428 THE VOYAGE OF H.M.S. CHALLENGER. 



The first joint free from trie side-plate, widening a little distally, but with the proximal 

 part very narrow, producing a sort of flask -shape with the neck a little bent ; the 

 second joint longer than the third, the front apex, where the joint is widest, being at 

 some distance from the following joint, except when that is bent upwards ; the third 

 joint as broad as long, the base much narrower than the somewhat squared distal 

 end ; the wrist attaining a much greater breadth than any of the other joints, the 

 distal breadth about equalling the length, the front margin convex, the hinder strongly 

 sinuous, the distal denticulate, with six little teeth and a large hind one with a small 

 one at its base ; the hand and finger are in shape and function like the finger and nail 

 of the gnathopods in many Amphipoda Gammarina ; the hand matches the length of 

 the distal margin of the wrist, upon which it closes ; its front margin is convex, the 

 hinder nearly straight ; the finger is slender, slightly curved, about a fourth of the length 

 of the hand, and when the hand is closed, the finger crosses the projecting apical tooth 

 of the wrist. 



Second Perseopods. — The side-plates more squared than the preceding pair, the 

 rounded lobe being at the top of the front and directed more upwards than outwards. 

 The limb is similar in shape to that of the first perseopods, but larger ; the hinder apex 

 of the third joint is much more sharply outdrawn, so that the distal breadth of this 

 joint is greater than its length ; the distal teeth of the wrist are much more pronounced, 

 varying greatly in size ; the length of the finger does not seem to be increased in 

 proportion to that of the hand, and, though socketed, it is perhaps not movably 

 jointed. 



TJiird Pev&o'pods. — Side-plates not large, broader than deep. The first joint 

 expanded but not greatly, about twice as long as broad, the front margin rather more 

 convex than the hind one, with shallow sparse serration and a small acute apex ; the 

 hind margin not reaching so far dowm as the front one, some serration faintly perceptible 

 on the distal half ; the second joint short, triangular, the front and the two hind margins 

 straight, with acute apices, the tw T o lower margins sinuous ; the third joint widening 

 distally, the hind margin longer than the front, the front apex and the hinder one acute, 

 decurrent ; the fourth joint large, the convex hind margin with an acute decurrent apex, 

 besides which the broad distal margin has six pronounced teeth, the front one very large 

 followed by a smaller, two very large, two smaller, connected with the apex by a rounded 

 angle, within which the fifth joint hinges ; the fifth joint, which here acts as finger, is 

 much longer than any of the other joints, and is sabre-like, acute, apparently wdth the 

 sixth joint entirely absorbed or absent. 



Fourth Perieopods. — Side-plates small. Branchial vesicles very complex. Limb very 

 like that of the third perseopods, but much smaller ; the first joint as long, but much 

 narrower, with the front margin less convex than the hinder ; the third joint has the front 

 process more produced than the hinder one, the joint being altogether as long as the 



