20 , EEV. T. E. E. STEBBINa ON THE 



Fifth perceopods. Side-plates small, with the hind margin crenulate. The branchial 

 vesicle directed forward, not much longer than broad, very much shorter and narrower 

 than the first joint of the limb. The first joint broader than in the preceding pair and 

 as long, the widest part not far from the base, the broad wing containing numerous 

 gland-cells, its irregularly convex border shallowly indented and fringed with spinules, 

 of which, as in the preceding pair, those at the upper part are much larger than those 

 below ; the front margin nearly straight or a little convex, with three or four groups of 

 spines ; the short second joint having a group of spines at the apex of the front ; the 

 third joint decidedly shorter than the fourth, with three groups of spines in front and 

 two or three behind; the fourth joint with four or five groups of spines on the front, 

 and three or four on the hind margin; the fifth joint subequal in length to the fourth, 

 but narrower, with three or four groups of spines in front and two behind ; the finger 

 straight, slender, tapering, about half the length of the fifth joint, with seven or eight 

 little nodules along the front margin, and the usual plumose cilium near the base. 

 The whole limb is a little shorter than that of the fourth pair, the difference being 

 chiefly owing to the shorter third joint. 



Pleopods. The peduncles of the first pair the longest, in all the pairs carrying one or 

 two groups of setae on the lower margin. The coupling-spines (retinacula'-) long and 

 slender, with five or six teeth, besides the strongly bent apex ; in general there are two 

 only of these organs on the peduncle, but in one instance four were counted ; there is 

 always a plumose spine with them ; the cleft spines on the first joint of the inner ramus 

 two or three in number ; the spoon-shaped arm much shorter than the serrate one ; the 

 inner ramus sometimes with sixteen, the longer outer one with twenty joints. 



Uropods. The stout peduncle of the first pair subequal in length to the outer ramus, 

 having on the outer margin one or two groups of setiform spines and a row of about 

 seven small spines, and a row of three on the inner margin ; the rami are not very long, 

 smooth, the inner much smaller than the outer, both strongly curved, although in some 

 positions the curvature may not be very distinctly seen ; peduncles of the second pair 

 rather shorter and narrower than those of the first, similarly armed, but with rather 

 stronger spines ; the rami subequal, the outer almost imperceptibly the longer, both 

 smooth, slightly curved, a little longer than the peduncle ; peduncles of the third pair 

 stouter than the preceding pairs, not longer than broad, having groups of spines about 

 the distal margin ; the rami long and moderately broad, extending for nearly their whole 

 length beyond the telson and the other uropods, subequal, fringed with numerous long 

 plumose setse ; in one specimen the outer ramus had on its outer margin twenty, two at 

 the apex of the little second joint, and eight on the inner margin ; the inner ramus had 



' In regard to the occurrence of the retinacula in various groups of Crustacea, and their phylogenetic import- 

 ance, see the interesting footnote in ' Caroinologisohe Mittheilungen,' ix. p. 220, by Paul Mayer, 1880. By Carl 

 Bovallius they had been recognized in his account of " Pterygocera arenaria." Dr. Boas calls them in German 

 " Hefthaken." "When I wrote my ' Challenger ' report these notices had escaped my attention. 



