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



the nail. As shown in the figure m:tp., PI. LXIL, in one specimen these maxillipeds 

 were not symmetrical. 



The triturating organs show an inner row of short sharp teeth, broad at the base 

 and apparently simple, while the outer row consists of long slender spines covered with 

 prickles or denticles. 



First Gnathojwds. — Side-plates greatly expanded below and outdrawn in front, with 

 cilia along the front margin, plumose setae fringing the lower, scattered on the inner 

 surface, and occurring at intervals on the hind margin. The first joint broad, rather bent, 

 reaching beyond the side-plate, with groups of spines near and at the distal end ; the 

 second joint with a group of spines at the hinder apex ; the third joint short, squarish, 

 with no free front margin, the lower hinder corner rounded and set with a group of 

 spines ; the wrist broader than long, the hind wing, which gives it something of a cup- 

 shape, being set both round the crenulate edge and on the inner surface with numerous 

 sjjines, which, like many of those on the preceding joints, are plumose in the middle, then 

 become finely pectinate and end seta-like ; the hand is large, longer than the wrist, from 

 a rather narrow base expanding greatly, with four groups of setse or spines near the long 

 convex front margin ; the hind margin is smooth, short, the difi'erence in length between 

 this and the other margin being made np by the great length of the convex palm, defined 

 by a curved spine, and fringed with closely set cilia, numerous setae and setules taking 

 their origin on each surface along the palm-border, while others arise on the inner surface 

 at some distance from it; the finger is of great length, slender, curving round the joalm, 

 the defining spine of which it a little overlaps, being itself smooth except for some 

 microscopic cilia within its inner margin and the dorsal cilium near its base. 



Second Gnathopods. — Side-plates of nearly even breadth throughout, the convex 

 lower margin fringed with numerous j^lumose setae. Branchial vesicles as long as the 

 first joint of the limb, with a small accessory lobe close to the narrow neck. The limb 

 in shape and details closely resembling the first gnathopods, but of greater length ; the 

 first joint extending much beyond the side-plate, the spines near the front apex strong ; 

 the third joint with strong spines extending less round the hinder and more round the 

 distal margin than in the first gnathopods ; the wrist of equal length and breadth, larger 

 than that of the preceding pair, the hand longer, without being broader, than in the 

 preceding pair. 



First Perieojyods. — Side-plates as in the preceding segment, but rather broader. 

 Branchial vesicles distally broader than those of the second gnathopods, with a small 

 oval accessory lobe near the neck. First joint reaching beyond the side-plate, with some 

 setae on the margins; second joint short; third joint longer than the fourth, not decurrent, 

 with three or four groups of setae on the hind margin, the apical groups long, and an 

 apical group in front ; the fourth joint like the preceding, narrowest at the base, subec^ual 

 in length to the fifth, with an apical group of setae in front, and on the hind margin four 



