1580 THE VOYAGE OF H.M.S. CHALLENGER. 



divided into blunt teeth, of which five or six are conspicuous, the rest near the apex 

 being small ; the front margin is only slightly convex, and has a sharp apex, a little 

 bent, with a small cavity behind it containing a spinule ; between this and the thumb 

 the distal margin is nearly straight ; the hand set on as in the preceding pair, widens 

 beyond the neck, and then tapers to the truncate apex, the front margin being convex, 

 the hinder gently crenate, scarcely convex ; the finger very short, its base occupying 

 nearly all the apex of the hand, its tip curving across the tip of the thumb ; there are 

 spinules along the hind margin of the wrist, and near the teeth of its distal process, 

 also near the margins and on the surface of the hand. In both the first and second 

 gnathopods there are gland-cells in the first five joints. 



First Perwopods. — Side-plates deeper behind than in front, the front margin convex 

 the other margins sinuous, the lower serrate. The branchial vesicles long oval, not so 

 long as the first joint. The limb long and slender ; the first joint concave in front, a 

 little widened distally, almost free from the side-plate, as long as the three following 

 joints united, having a longitudinal ridge on the under surface ; the second joint not 

 shorter than the breadth, carrying two spinules on the convex hind margin ; the third 

 joint rather longer than the fourth, with some very small spinules on the slightly 

 convex front margin, the hind margin nearly straight, fringed with numerous out- 

 standing spinules ; the fourth joint not much narrower, similarly armed ; the fifth 

 subequal in length to the fourth, similarly armed, a little curved, distally tapering ; the 

 finger slender, acute, a little curved, scarcely more than a fifth of the length of the 

 fifth joint. 



Second Per&opods. — Side-plates rather broader than in the preceding pair, 

 branchial vesicles and limbs similar, but the joints rather longer, except the second and 

 the finger ; the fourth joint not quite so long as the fifth. 



Third Perseopods. — Side-plates a good deal broader than deep, the hind lobe the 

 larger, with its lower margin flattened ; on the inner side there is a narrow tapering 

 process directed downwards. Branchial vesicles subequal in length to the first joint, 

 but not so broad. The first joint greatly expanded, rather longer than the first joint 

 of the preceding pair, irregularly oval, narrower at the base than distally, the hind margin 

 very convex and regular, finely not deeply serrate, the front margin nearly straight in 

 the upper part, carrying a few spinules, the lower part convex, strongly serrate, its 

 apex produced into a sharp point, the distal margin sinuous ; the rest of the limb slender, 

 similar to the preceding pair, but with the third and fifth joints considerably, the second 

 and fourth a little, longer and somewhat thicker, the second joint with a minute spinule 

 in a notch above the front apex. 



Fourth Perseopods. — The side-plates as deep as the preceding pair, not so broad, the 

 front and hind margins nearly straight, but the front rounded at the lower corner, the 

 hinder produced into a small projection. The branchial vesicles broadly oval, but not so 



