1206 THE VOYAGE OF H.M.S. CHALLENGER. 



plate. The limb closely resembles that of the first gnathopods, but the joints are rather 

 longer and broader, and the spines on the hand are stronger and more numerous. 



First Perseopods. — The side-plates broader than the preceding pair, the hind margin 

 ending in a slightly produced point. The branchial vesicles about as long and broad as 

 the first joint. The marsupial plates more than twice as long as the branchial vesicles, 

 with a breadth more than half the length, the longest of the surrounding setse scarcely 

 equal to half the breadth. The first joint almost free from the side-plate, the front 

 margin a little sinuous, with some spines near the apex, a second margin in front forming 

 a lobe at the lower part of the joint, on the lower rim of which there are spines ; the 

 hind margin has three or four groups of spines ; the second joint is short, with three 

 spines at the apex behind ; the third joint is much shorter than the fourth, widening a 

 little distally, with spines at the apex in front, and at two points of the hind margin ; the 

 fourth joint as long as the first, shorter than the fifth, with four groups of spines on the 

 front and three on the hind margin ; the fifth joint with several groups of spines on both 

 margins ; the hind margin interrupted at a little distance above the apex, and armed with 

 some stout spines, of which one is very prominent, fitted for the impinging of the finger ; 

 the apex itself has a stout spine and some small ones ; the finger is short and stout, 

 little more than a third the length of the fifth joint, the nail curved, acute ; there are 

 small setules along the outer margin and some submarginal to the inner border. There 

 is no appearance of gland-cells in the limb or of any opening in the finger-tip. 



Second Perseopods. — The side-plates broader than the preceding pair, with convex 

 front margin ending in a rounded apex, the hind margin produced more deeply in a 

 triangular apex, the lower margin between these two apices being concave. The 

 branchial vesicles rather larger than in the preceding segment. The marsupial plates 

 distally of immense breadth, the surrounding setae short. The limb is broken ; the three 

 remaining joints are similar to those of the first perseopods ; it can here be seen that the 

 apex of the front margin in the third joint is emarginate. 



Third Perieopods. — The side-plates broader than the preceding pair ; the front lobe 

 somewhat squared, but with a convex front and sinuous lower margin ; the hind lobe 

 tending to triangular, the combined front and lower margin carrying some spinules, the 

 hind margin sinuous. The branchial vesicles greatly dilated, nearly as broad as long. 

 The marsupial plates, or at any rate one of them, much narrower than the branchial 

 vesicles, not once and a half as long. The first joint of the limb not winged, but 

 tolerably broad, the front margin convex, with five groups of spines, the hind margin 

 double, one smooth, and slightly concave except at the top, the other carrying two groups 

 of spines ; the second joint short ; the third similar to that of the preceding perasopods, 

 and having, as they also appear to have, a lobe behind higher up than the apex ; the 

 other joints missing. 



Fourth Perseopods. — The side-plates narrower than the preceding pair, the front lobe 



