1152 THE VOYAGE OF H.M.S. CHALLENGER. 



The specimen was mounted in Canada balsam during the voyage, and the full figure 

 was drawn from the animal thus mounted, but in subsequently dealing with it for pur- 

 poses of dissection I had the misfortune to lose almost all the parts, except fragments 

 of the antennae and some of the peraeopods. Luckily some important details had been 

 drawn before the accident, but it must be understood that these were, subsequently 

 described from the drawings, not, as in other instances, from the mounted dissections. 

 It may perhaps be worth while to remark that in the full figure it is the larger 

 gnathopod which is the first, though its terminal joints are to the rear of the smaller 

 second gnathopod. 



Upper Antenna}. — The first joint rather longer than the head ; the second thinner 

 and considerably longer, with slender spines on the lower margin ; the third joint rather 

 longer than the second, the margins serrate, the under fringed with long spines ; the 

 flagellum of eight joints, the first longer than any of the others, all together not so long 

 as the first two joints of the peduncle, all carrying long slender spines on the under 

 margin ; the secondary flagellum of one slender joint, together with its apical setae not so " 

 long as the first joint of the primary. 



Lower Antennae. — The first two joints very short, the third much longer than the 

 two preceding, but shorter than the first of the upper antennae ; the fourth and fifth 

 joints about equal respectively to the second and the third of the upper antennae, and 

 similarly armed ; the flagellum of nine joints rather longer than the flagellum of the 

 upper antennae, the terminal joint less minute. 



Mo.ndibles.- — The cutting edge on the left mandible with five teeth ; the secondary 

 plate with four teeth ; the spine-row, I believe, with only three denticulate spines ; the 

 molar tubercle prominent, with rounded dentate crown ; the palp of great length, the 

 first joint short, the second very long, with only a few spines observed on the front 

 margin, some perhaps on the lower part broken off or not noticed ; the third joint a 

 little shorter than the second, with the front and hind margins gently convex, the apex 

 almost pointed, the front margin having a series of long spines beginning near the base, 

 first with two spaced singly, these being followed by seven pairs. 



First Gnathopods. — The first joint shorter and very much narrower than the hand, 

 the hind margin more convex than the front ; the second joint short, with a group of 

 spines near the apex behind ; the third joint with convex front margin produced to a 

 pointed apex upon the wrist, the hind margin convex, with a group of spines where it 

 joins the oblique lower margin ; the wrist longer than broad, much shorter and narrower 

 than the hand, but distally much broader than the preceding joints, with a group of 

 spines near the apex of the convex front margin, and three groups along the hind 

 margin ; the hand very large, oval, not quite twice as long as broad, with spines at seven 

 points of the front margin, not including any large groups, and about as many groups 

 on the hind margin, more closely set and containing more spines ; the palm curiously 



