REPORT ON THE AMPHIPODA. 1045 



the second, with a spinule on the straight hind margin and another at its apex, the 

 convex front margin having several slender setiform spines, and a strong apical spine ; 

 the fourth joint longer than the fifth, broad and straight, fringed in front with slender- 

 spines, and having at the apex a long strong one ; within the smooth hind margin there 

 are three groups of short spines, and a complex apical group with three slender spines, 

 four short stout ones, and one or two that are long and stout ; the fifth joint with 

 eighteen slender spines or setae along the serrate front margin, some long spines on its 

 produced apex, the hind margin straight and smooth ; the finger very short, abruptly 

 upturned, with a dorsal cilium and a dorsal denticle. 



Fourth Perasopods. — The side-plates deeper in front than behind, with some feathered 

 seta? on the lower part of the front margin and the hinder part of the lower margin. The 

 branchial vesicles as in the preceding segment, but rather smaller. The first joint larger 

 than in the preceding pair, its greatest breadth equal to the length, in front projecting in 

 a, great rounded angle, the sides of wdiich are straight, the lower side longer than the 

 upper ; about the angle there are some feathered setae, and spinules on other parts of the 

 margin ; the apex forms a narrow, scarcely decurrent, little lobe ; the hind margin is much 

 and evenly curved, armed with a few r spinules ; the second and third joints are much as 

 in the preceding pair ; the fourth joint is strongly spined along the front margin, having 

 five long spines, and a dozen others smaller, of different lengths ; within the hind margin 

 are several short spines on the surface, the apical group being in general as in the third 

 perasopods, the two long spines being denticulate in the lower portion ; the fifth joint is 

 longer than in the preceding pair, but still not quite so long as the fourth ; its serrate front 

 margin and apex carry eighteen long spines ; the hind margin has one submarginal spine ; 

 the tiny finger has three dorsal denticles, its distal half abruptly narrower than the 

 proximal, and carrying two little curved dorsal setules, possibly marking the base of a 

 nail. 



Fifth Per&opods. — The side-plates shallow, the lower margin preceded by plumose 

 setae, and fringed with slender spines. The first joint with the front margin nearly 

 straight, armed with eleven spinules ; the lower margin crossing the top of the second 

 joint, behind descending much below it ; the hind margin smooth, sloping backwards 

 with a gentle convexity to join the upward curve of the lower margin, the whole free 

 part of which is densely fringed with plumose setae ; the greatest breadth of the joint is 

 at the meeting of the hinder and lower margins ; there are many long setae on the inner 

 surface ; the second joint is short, with two or three small apical spines in front ; the 

 third joint is longer than the second, the decurrent apex in front having four small 

 spines ; the hinder apex acute, much more decurrent ; the hind margin fringed with 

 about a dozen long plumose setae, of which one on the apex is of great length ; the fourth 

 joint longer than the third, with some short spines on the hinder apex, the front margin 

 very convex, with five groups of short spines on the surface near it, a spine and spinule s 



