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



form. The first joint but little expanded, much longer than broad, broadest near the base, 

 hind maro-in nearly straight and smooth, front margin slightly curved and serrate, both 

 closely fringed with setaa, of which many on the front margin are densely plumose ; on 

 the inner surface the inner margin of the unexpanded joint, as distinct from that of 

 the wino- or expansion of it, carries numerous setse, some of which are densely plumose 

 and of great length ; the second joint very short, the third rather long, shorter than 

 the first, crowded with long spines and plumose setse on the front margin, and with 

 plumose setse on the hind margin ; it expands a little from the narrow base and 

 contracts towards the distal end. Eemainder of the limb missing. 



Fourth Perwojjods. — Side-plates deeper behind than in front. First joint broader 

 than in the preceding pair, but not longer, the upper part rounded behind ; the 

 armature and general structure of the limb similar to that of the third perseopods, but 

 the third joint longer than the first, with some long spines at and near the apex in front, 

 a suture or groove crossing the joint for half or more of its breadth a little way from the 

 apex ; the fourth joint much narrower and shorter than the third, with some short setse 

 and long spines on the front margin ; the spines with curved ends, one of them equalling 

 the length of the joint. Eemainder of the limb missing. 



Fifth Perseopods. — Side-plates with the upper margin produced to a small point. 

 The first joint expanded, sloping away on both sides from the neck, the front margin 

 very convex, fringed with small spine-like setse, the hind margin sinuous, convex above, 

 with longer setse, and a small apical lobe set with spines not overlapping the second joint ; 

 the joint being much thickened where the chief muscles lie presents a surface depression 

 along the hinder expansion ; the second joint with its front and hind margins unusually 

 free ; the third joint narrower but not shorter than in the preceding pair, of almost 

 uniform width throughout, the apex scarcely decurrent, eight groups of spines on the 

 front margin, spines and setas fringing the hinder margin. Eemainder of the limb missing. 



Pleopods. — The pair of coupling spines very small, the terminal hook bent sharply 

 downwards ; a lateral tooth at some distance below ; there are many small retroverted 

 teeth along the outer margin ; such teeth I believe to be not uncommon, but as they do 

 not project they are in many species very difficult to discern ; the outer distal end of the 

 peduncle produced into a curved tongue ; the cleft spines forming a row of nine, those at 

 the top short ; the joints of the inner rami twenty, of the outer twenty-two in number. 



Uropods. — The peduncles of the first pair longer than the inner ramus, closely 

 fringed with spines on two edges, the rami narrow, stiliform, the inner with six spines 

 along the upper margin, not beginning close to the base and not nearly reaching the acute 

 apex ; the outer ramus broken, with six spines on the upper part, stouter than those of 

 the inner ramus ; the peduncles of the second pair longer than the subequal stiliform 

 rami, with a row of seta-like spines on the surface, with spines all along the lower edge 

 and along more than the distal half of the upper ; several spines along the edges of the 



