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



Stenopleura atlantica, n. sp. (PI. LXXXIV.). 



Rostrum inconspicuous, lateral lobes of the head small, somewhat pointed ; the 

 postero-lateral angles of the first three pleon-segments not drawn out to a point ; the 

 fourth pleon-segment with a dorsal depression. 



Eyes high up on the sides of the head, longer than broad, large, with numerous 

 very small ocelli. 



Upper AntennsB. — The peduncle short, about as long as the head, the second joint 

 thinner and shorter than the first, the third than the second ; the flagellum of thirty- 

 three joints, the first much longer than the third joint of the peduncle, carrying some 

 cylinders, the next twelve joints short, not thick, the remainder again longer, filiform. 



Lower Antennae. — The first three joints of the peduncle very short, the first a little 

 expanded, gland-cone inconspicuous ; the fourth joint longer than the preceding three 

 united ; the fifth shorter and thinner than the fourth, like it having groups of cflia or 

 setules along the upper margin ; flagellum filiform, of thirty -five joints. 



Mandibles. — Cutting plate short, with widened distal margin, not curved down- 

 wards, divided into nine teeth, of which the lowest three are the largest, the lowest but 

 two larger than the others ; the secondary plate on the left mandible also short and 

 broad, distally divided into eight teeth, none large, the lowest larger than the rest ; on 

 the right mandible no secondary plate could be clearly made out ; spine-row of three 

 strong, not smooth spines, amidst a row of cilia ; on the right mandible there were only 

 two strong spines, a difference in number which, as well as the apparent absence of a 

 secondary plate, might possibly be due to accident, but the same difference in the 

 number of spines of the spine-row was observed in D examine jiinder si, and is noticed 

 by Schneider in Dexamine thea, Boeck ; the molar tubercle with twelve or thirteen 

 rows of rather strong denticles ; the first joint of the palp short, with a narrow base ; 

 the second joint large, narrowest at either end, hind margin a little concave, front very 

 convex, with five or six slightly plumose spines along its course ; the third joint much 

 thinner than the second, but of about the same length, with five or six spines on the 

 front margin, three at the apex, one on the surface behind near the base, and many 

 adpressed cilia on the surface near the apex and near the front margin, beyond which 

 some of them project. 



First Maxillw. — Inner plate small, with a single plumose seta on the middle of 

 the rounded apex ; the outer plate with a small tuft of cilia at the distal end of the 

 inner margin, the truncate distal margin carrying ten spines in two rows, five long and 

 slender, minutely denticulate, in one row, in the other four that are shorter, but one 

 that is long and stout, this being the next to the outermost ; the spines in this second 

 row appear to have but a single denticle or none ; the second joint of the palp is long, 

 overtopping the outer plate, with five slender spine-teeth, serrate on both edges, set 



