1044 THE VOYAGE OF H.M.S. CHALLENGER. 



straight, with a small apical tooth. The branchial vesicles broad, not quite so long as 

 the side-plates. The marsupial plates narrow, longer than the branchial vesicles. The 

 first joint not reaching the end of the side-plate, the setae on its hind margin of great 

 length ; the second joint having setse or spines at three points of the hind margin ; the 

 rest of the limb nearly as in Ampelisca acinaces, but narrower, with more spines on the 

 hind margin of the third joint ; the hand less than half the length of the wrist, set over 

 the inner surface with many rows of short spines ; six of the spinules which fringe the 

 inner margin of the narrow finger are spinous on two edges, the seventh, which lies 

 beside the nail and is of equal length with it, appears to be smooth. 



First Perieopods. — The side-plates of nearly equal width throughout, the hind 

 margin without an apical tooth. The branchial vesicles broad, longer than the side- 

 plates. The marsupial plates narrow r ; longer than the branchial vesicles. The limb 

 differing little from that of Ampelisca acinaces; the hind margin of the first joint more 

 convex ; the third joint apically narrower ; the fourth joint with many long setae on the 

 hind margin, and at the apex of the front one long and one short seta ; the fifth joint 

 fringed w r ith setse and slender spines along more than half the convex front margin, but 

 with only two straight slender spines standing out from the hind margin ; the finger a 

 little longer than the two preceding joints united. 



Second Perseopods. — Side-plates with the front margin very slightly convex, the 

 excavation behind of little depth, the hind margin below the acute upturned angle being 

 nearly as long as the front margin. The first joint of the. limb about reaching the 

 end of the side-plate, fringed with numerous seta?, those in the middle of the hind 

 margin being longer than those lower down ; the second joint having the hind margin 

 fringed with plumose setse ; the third joint longer than in the preceding pair, densely 

 fringed on both margins ; the short fourth joint fringed on the hind margin except near 

 the base, and with an apical group in front ; the fifth joint having spines or setse along 

 the lower half in front, and on the hind margin three slender spines, each with an 

 attendant spinule ; the finger longer than the two preceding joints united, a short dorsal 

 cilium close to the hinge ; as in the preceding species, there is on the front margin of 

 the third joint a series of long setse strongly but loosely feathered, and another series 

 densely feathered. 



Third Perseopods. — Side-plates broad but not deep, the front lobe wider and rather 

 deeper than the hinder one. The branchial vesicles small, bent forwards across the first 

 joint, but not reaching the front of it. The marsupial plates short and narrow, with nine 

 setae. The first joint large, its greatest breadth exceeding the length, the front margin 

 describing an immense curve, fringed, except at the lower part, with some setse and 

 small spines, the hind margin double, nearly straight, as if soldered above to the side- 

 plate, neither this nor the front margin at all overlapping the short second joint, which 

 has a couple of spinules on the front apex ; the third joint once and a half the length of 



