1048 THE VOYAGE OF H.M.S. CHALLENGER. 



joint, and which has a small secondary process projecting from its inner surface ; the 

 second joint is long and broad, at the base projecting over the first joint in front, 

 its hind margin slightly concave, carrying spines at seven points, the front margin 

 fringed with stiffer spines, which towards the slightly narrowed truncate apex are of great- 

 length ; the third joint moderately broad, though a good deal narrower than the other 

 two, longer than the first, considerably shorter than the second, with two groups or rows 

 of spines near the top of the hind margin, three or four groups along the front, and 

 some strong spines on the slightly rounded apex, one of the spines being conspicuous 

 among the rest for its size. 



Lower Lip much the same as in Ampelisca chiltoni. 



First Maxillas. — The inner plate rather long, with a plumose seta on the inner 

 margin below the apex, and a shorter spine or seta on the apex as in Ampelisca 

 acinaces ; of the eleven spines on the outer plate the innermost, which is as usual straight, 

 has three tiny denticles some way below the apex on the inner margin, the next has 

 two denticles on the outer margin, the rest, except the outermost, being more or less 

 denticulate, but none strongly, so that the spines appear smooth except under a high 

 power ; the second joint of the palp is strong, nearly parallel-sided, its distal teeth 

 acute, and the five spine-teeth slender ; there are seven or eight submarginal spines. 



Second Maxillee differing little from those of Ampelisca chiltoni. 



Maxillipeds in general like those of Ampelisca chiltoni, but resembling Ampelisca 

 acinaces in having the distal margin of the inner plates sloping outwards ; the plumose 

 setse descending to nearly the middle of the inner margin ; the large outer plates have 

 from eleven to twelve or thirteen spine-teeth along the inner margin, and eleven spines 

 on the broadly convex distal margin, the outer six of the latter being rather setiform ; 

 the third joint of the palp is shorter than in Ampelisca chiltoni, with numerous and 

 strong sjrines on the surface as well as the inner margin and apex and upper part of 

 the outer margin ; the finger is longer than the third joint, and has six long decurrent 

 spinules on the inner margin as it approaches the nail, which constitutes about half the 

 length of the finger. 



First Gnathopods. — Side-plates directed forwards so as to cover the basal joints of 

 the lower antennse, rather wider below than above, the lower margin very convex though 

 irregularly, with the usual setse, the lower row inserted with some regularity ; the hind 

 margin is slightly convex, and below curves round to a small apical tooth. The first 

 joint not reaching the end of the side-plate, proximally narrow, but for the most part 

 very wide, with the usual armature ; the second joint broader than long, with one or two 

 small spines low down on the hind margin and an apical group of plumose setse ; the 

 third joint broad, widening distally, its hind margin fringed with plumose setse and 

 spines ; on the inner surface transverse rows of long spines are inserted at various 

 heights above the apex ; the wrist is of great breadth, where free from the third joint its 



