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



19. Eupliausia antarctica, G. 0. Sars (PI. XV. figs. 1-8). 



Euphausia antarctica, G. 0. Sars, Preliminary Notices on the Challenger Schizopoda, No. 18. 



Specific Cliaracters. — Form of l)ody ratlier slender, with tail less powerful in 

 development than is generally the case. Carapace without any lateral denticle ; anterior 

 part slightly keeled above and projecting as a broad, triangular, frontal plate. Caudal 

 segments smooth above, with remarkably small, rounded epimera. Last segment 

 slightly exceeding in length the preceding, with a minute, simple, preanal spine. Eyes 

 claviform. Antennular peduncle slender, without any dorsal lobe, l_)ut with the outer 

 corner of the basal joint produced into a sharp spine. Antennal scale obloug-Hnear, 

 obtusely truncate at apex, outer corner jutting out as a well marked dentiform pro- 

 jection. Mandibular palp remarkably slender, with terminal joint linear. Last joint of 

 second pair of maxillae oblong-ovate. Legs very elongate and densely setose. Telson 

 with three pairs of dorsal denticles ; subapical spines moderate in size, smooth. Uropoda 

 much shorter than telson, inner plate slightly overreaching outer. Length 1 7 mm. 



Remarks. — This is a rather anomalous form, and readily distinguished from all 

 the other species by the remarkably narrow tail and very slender legs, as also by the 

 broad triangular frontal plate and the form of the antennal scale. 



Description. — All the specimens collected are females, and the largest measures about 

 17 mm. in length. 



The form of the body (see PI. XV. fig. 1) is rather slender, and the proportion 

 between the anterior and posterior divisions somewhat different from that observed in 

 most of the other species, the tail Ijeing relatively far less powerfully developed. 



The carapace lacks every trace of lateral denticles, the inferior margin being quite 

 smooth and but very slightly incurved along their anterior part. The antero-lateral 

 angles of the carapace project considerably and are acutely angular ; the frontal 

 part (see fig. 2) protrudes over the base of the eyes as a broad horizontally extending 

 plate of triangular form, reaching nearly to the middle of the basal joint of the 

 antennulse. From the l^ase of the plate, a slight dorsal keel is seen to extend backwards 

 along the anterior part of the carapace. 



The caudal segments are smooth above and rather narrow, the epimera being 

 comparatively very small and evenly rounded. The last segment but slightly exceeds 

 in length the preceding, and has a very small, simple preanal spine (fig. 4), mostly 

 hidden between the bases of the uropoda. 



The eyes (see fig. 2) project considerably, but have the cornea not very much 

 expanded, with the greatest breadth about the middle of the pedicle. 



The antennular peduncle (ibid.) is comparatively slender, and lacks every trace 

 of dorsal lobes, but has the outer coi-ner of the basal joint jutting forth as a sharj_), 

 spiniform projection. 



