8G4 THE VOYAGE OF H.M.S. CHALLENGER. 



special crenulation is provided just within the palm-margin ; the finger is long and 

 curved to fit the palm ; by the bending forward of the hand in the channelling of the 

 wrist the finger would be enabled to touch the expanded portion of the wrist, which 

 may thus be adapted to assist in the act of grasping ; the dorsal^eilium close to the 

 hinge, minute. 



Second Gnatho'pods. — Side-plates larger and deeper than those of the first gnatho- 

 pods, similar, except that the front margin has no abrupt bend. Branchial vesicles 

 with a narrow crumpled neck, the whole length about equal to that of the first joint. 

 The marsupial plates narrowing distally, set closely round with very numerous and long 

 setaj, more closely on the front than on the hind margin. The limb closely resembling 

 that of the preceding pair in shape and the details of its armature, but the first joint 

 considerably longer and more out-bowed on the hind margin, the wrist shorter than the 

 first joint, its wing, unlike that in the first gnathopods, produced beyond the front 

 margin so as to form a calx, though not a long one ; the hand and finger but little 

 longer than in the preceding pair ; in each pair the finger has some small stifi" hairs on 

 the inner margin. 



First Perieopods. — Side-plates with the front margin nearly straight, descending 

 considerably below the preceding pair and free from it except at the convex upper part 

 of the margin ; the short slightly emarginate lower border makes a sharp angle with 

 the front; the plate is thickened and its surface almost rigid near the hind margin, 

 which is overlapjjed by the following plate. The branchial vesicles, of tolerably even 

 width to the rounded apex, are longer than the first joint of the limb. The first joint 

 reaches much below the side-plate, abo.ut ec[uals the length of that of the preceding 

 pair, with similar armature and a slight tendency to the out-bowing of the hinder 

 margin, which forms a ridge ; the second joint with two groups of spines on the hind 

 margin ; the third joint elongate, not quite so long as the first, narrow, slightly curved, 

 a very little expanded and decurrent at the distal end, with spines at some seven points 

 of the hind margin, and some spinules in front ; the remainder of the limb missing, 

 unfortunately, not only in this but in all the perseopods. 



Second Perasojwds. — The side-plates shorter than in the preceding pair, excavated 

 behind for little more than a quarter of the depth, from the angle of the excavation the 

 margin slanting forwards to form a sharp angle with the lower point of the sinuous front 

 margin. The branchial vesicles, marsupial plates, and joints of the limb as in the 

 preceding pair. 



Third Perseopods. — The side-plates broader than deep, the front lobe larger than the 

 hinder, the hinder with its lower margin fiattened. Branchial vesicles broader than in 

 the preceding pairs ; marsupial plates similar. First joint of the limb rather longer than 

 in the preceding pairs, a little expanded behind near the base, and distally in front, the 

 armature slight, both front and hind margins carinate ; the third joint similar to that of 



