REPORT ON THE AMPHIPODA. 1055 



joint has many plumose setae on the lower two-thirds of the convex front margin, the 

 hind being nearly straight, with a spine and seta at three points near the centre, the 

 lowest seta being the longest ; the finger is longer than the two preceding joints united, 

 not much curved. 



Second Per&opods. — The side-plates broad for almost the whole length, the angle 

 below the hinder excavation upturned, acute, the margin below it only slightly oblique 

 except at starting, forming a rounded corner with the long nearly straight lower margin. 

 The first joint a good deal curved forwards, much of the convex hind margin strongly 

 fringed with setae, the front margin also carrying them on the lower part ; the second joint 

 has five plumose setae along the hind margin ; the third joint is as usual longer than in 

 the first perseopods, and densely fringed on both margins ; the short fourth joint has 

 many setae on the hind margin and a group on the front apex ; the fifth joint is longer 

 than in the preceding pair, but is similarly armed on both margins ; the finger is long 

 and but slightly curved. 



Third Perseopods. — The side-plates broad, the front lobe deeper than the hind one. 

 The branchial vesicles large, bent forward across the top of the first joint, but not 

 reaching beyond the margin. The marsupial plates short and narrow, without setae. 

 The large first joint resembling that in Ampelisca chiltoni, the front margin except the 

 upper part fringed with plumose setae, and below a little overlapping the second joint ; 

 the lower part of the hind margin having a few spinules ; the second joint with two or 

 three spinules on the front apex ; the third joint with slender pectinate spines along the 

 convex margin and two at the hinder apex, also a strong bent spine at the front apex ; 

 the fourth joint with five strong spines and several slender ones on the front margin, 

 three or four surface groups near the hind margin, and a large apical group fringing the 

 lower margin, with five small spines and three large ones which are of very differing 

 lengths but all three distally denticulate ; the fifth joint, which is nearly as long as the 

 fourth, but much narrower, has three spines on the slightly concave hind margin, the 

 insertion marks of nine or ten on the convex front, and two spines on the produced 

 apex ; the small sharp finger has two dorsal denticles more prominent than usual, and 

 two little curved setules at what may be the base of the nail. 



Fourth Per&opods. — The side-plates deeper in front than behind, the front margin 

 carrying some spinules and setae, the lower margin behind little curved, fringed with setae. 

 The branchial vesicles as in the preceding segment, but narrower. The large first joint, 

 as usual, bowed out in front, and there carrying seven plumose setae, the rest of the 

 margin having small spines and spinules, below somewhat overlapping the second joint ; 

 the rounded lower margin projecting much behind the second joint, the hind margin 

 for much of its course straight, armed with small spines ; the second joint with apical 

 spinules in front ; the third joint fringed with spinules in front, and having a spine at 

 the apex, the apex behind carrying a short stout spine and two that are setiform ; the 



