1594 THE VOYAGE OF H.M.S. CHALLENGER, 



Oxycephalic. He does not mention the extreme development of the upturned apex of 

 the first joint of the flagellum in the male upper antennas of Leptocotis, except in the 

 description of the type-species ; nor would the character be of much use, since it 

 probably only belongs to a limited portion of the animal's life, 



Leptocotis ambobus, n. sp. (PI. OCV.). 



Head as long as perseon with the first two segments of the pleon, the neck 

 depressed, more than half the total length of the head in front of the eyes, the rostral 

 tract in front of the upper antennas narrow and slightly arched, rather more than a 

 third of the total length of the head ; the first three segments of the pleon with the 

 lower margins finely serrate, the postero-lateral angles of the first two segments not 

 outdrawn, but those of the third segment much outdrawn and acute, those of the 

 fourth segment acute, but only little outdrawn ; the double segment elongate, with 

 sharp lateral edges and two dorsal ridges traversing its whole length. 



Eyes not nearly reaching the point at which the upper antennae are inserted, 

 the front ocelli the smallest, the ocular pigment long, but the principal point from 

 which the ocelli appear to radiate situated low down and much behind the centre of 

 the eye. 



Upper Antennse attached considerably in advance of the eyes, at about a fourth of 

 the whole distance between these and the apex of the rostrum ; the first joint of the 

 peduncle much longer than broad, the second short and imperfectly developed ; the 

 first joint of the flagellum very much longer than the peduncle, the convex side 

 carrying a thick brush of filaments, the apex upturned at a right angle with the main 

 portion of the joint, forming a prominent, tapering process with a few filaments on 

 the almost straight outer margin ; the three following joints are very small and 

 narrow, lying back against the first joint, in line with the apical process, but pointing 

 in the opposite direction. 



Lower Antennse. — The third (first free) joint of the peduncle elongate, curved near 

 the base, distally thickened, fringed with short filaments ; the fourth joint a little but 

 decidedly longer than the third, more slender, with each end a very little thickened ; 

 the fifth joint of about the same length as the fourth ; the first joint of the flagellum 

 very slender, nearly as long as the third joint of the peduncle ; the second joint 

 minute, with the fringing filaments only at two points. 



Epistome apparently almost semicircular in outline, but bent so that the two 

 divisions of the front surface produce an angular projection down the centre. 



Mandibles.— The trunk very short compared with the length of the palp ; the 

 secondary plate on the left mandible similar to the principal, but smaller ; the first 

 joint of the palp slender, a little shorter than the first joint of the flagellum of the 



