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



Description. — Four specimens only of this form were collected, the largest of which, 

 a male, has a length of 26 mm. 



The form of the body (see PI. XVI. fig. 9) appears much more robust than in the two 

 preceding species, and a good deal comj)ressed. 



The carapace is rather short in proportion to its height, and has on either side, 

 posterior to the middle, a very strong denticle, which, however, does not, as is generally 

 the case, project from the inferior margin, but occurs at some distance above it, arching 

 over a sinus, from which a ridge extends anteriorly, joining the margin at the side of 

 the mandibles. The anterior part of the carapace is provided with a very marked dorsal 

 crest, jutting out in the middle as an ei-ect tooth. The rostral projection is remarkably 

 strong, projecting horizontally as a sharp dagger-like process, reaching nearly to the 

 end of the basal joints of the antennulas. Above the eyes, moreover, the frontal margin 

 juts out, on either side, as a well-marked, somewhat upturned dentiform projection, or 

 supra-orbital spine. 



The caudal segments are powerfully developed, and provided with rather large 

 lamellar epimera. Of these the two anterior pairs are almost c[uadraugular, whereas 

 the three posterior ones exhibit a more pronounced triangular form, their posterior angle 

 being slightly produced. The third segment, as in Euphausia mucronata, projects 

 posteriorly as a strong dorsal spine, pointing straight backwards, and has, moreover, 

 extending from the posterior margin, on either side an angular lobe. Again, the two 

 succeeding segments are distinguished liy their posterior margin lieing divided into 

 several pointed lappets, one of which occupies the median line dorsally. The last 

 segment is much narrower and more elouo-ate than the other, althoug-h not attain- 

 ing the length of the two preceding segments taken together. The preanal spine 

 (fig. 16) is distinctly bidentate, or has a rather strong secondary tooth at the posterior 

 edge. 



The eyes (see figs. 9, 10) are very short and thick, almost globular, with the cornea 

 exceedingly expanded. 



The antennular peduncle (ibid.) is rather slender, and distinguished more par- 

 ticularly by the pi'esence of a broad, but very thin and memljranous, dorsal lobe, 

 extending from the end of the basal joint and overlapping the base of the succeeding 

 joint. This lobe, too, is divided at the edge into several acute lappets (see fig. 12), 

 somewhat irregularly disposed, and forming two or three bunches. Another and very 

 much smaller lobe is found to project from the second joint, being almost spiniform in 

 shape, with a small lateral lappet proceeding from the outer edge (see fig. 13). 



The antennal scale (see fig. 10) projects appreciably beyond the second joint of 

 the antennular peduncle, and exhibits an oblong-linear form, ^\-ith the apex narrowly 

 truncate and the outer corner jutting out as a well marked dentiform projection. 



The oral parts could not be more closely examined for want of sufficient specimens. 



