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



Habitat— Station 122, September 10, 1873; lat. 9° 5' S., long. 34° 50' W. ; off 

 Barra Grande ; depth, 350 fathoms ; bottom, red mud. Two specimens ; one male, one 

 female. Trawled. 



The rostrum is compressed laterally, depressed slightly from the level of the dorsal 

 surface to beyond the reach of the eye, and then gradually rising in a straight line; it 

 is smooth on the upper side from the apex to the base, where, on a line with the 

 extremity of the third joint of the first pair of antennae, there stands one small tooth, 

 and at a little distance behind a row of teeth that gradually decrease in size posteriorly. 

 In the male there are seven, in the female only five such teeth ; but there is only one 

 specimen of each for comparison. The surface of the carapace is smooth and polished ; 

 the anterior margin is produced to a small tooth at the antennal angle, and another at 

 the fronto-lateral angle. 



The pleon is smooth and laterally compressed, especially behind the third somite, 

 which is produced posteriorly in the median line, to a slight extent in the male, but 

 forming a sharp point in the female, the point, when the pleon is extended, lying in close 

 proximity to the surface of the next succeeding somite. 



The ophthalmopoda (fig. la, a) are orbicular, and stand upon extremely short and 

 slender pedicles, attached to the ophthalmic somite, which is free and external to the 

 carapace; it lies across the frontal surface, and is produced in the median line to a strong 

 pointed cusp or tooth. 



The first pair of antennas (fig. lb) has the first joint broad, deeply hollowed and 

 furnished on the outer side with a broad, flattened, and pointed stylocerite, which follows 

 the contour of the deep excavation in which the eye rests ; the anterior margin of the 

 joint is fringed with a row of posteriorly directed cilia. The second and third joints are 

 short, and terminate in two flagella, the outer of which is the broader ; it is compressed 

 for a considerable distance, and then suddenly narrows, becoming slender and cylindrical. 

 The two flagella are subequal, and about twice the length of the rostrum. 



The second pair of antennas (fig. lc) is armed with a sharp spinedike tooth on the 

 under side of the outer distal margin of the second joint, near the base of the scaphocerite, 

 which is long, narrow, and rather more than half the length of the rostrum ; the distal 

 extremity is narrower than the base, and has on the outer margin a small subapical tooth 

 passing beyond the apex ; within the margin the upper surface is traversed by a longi- 

 tudinal groove. The flagellum of this antenna is broken off in both specimens, but I 

 judge it to be a little longer than those of the first pair. 



The anterior labrum orepistom a (fig. 1, ant.) is transversely ridged and longitudinally 

 short, and is produced anteriorly to a long projecting tooth in the median line. The 

 metastoma (fig. 1, post.) is transversely wider and shorter; between these two the 

 mandibles articulate on each side. 



