7G THE VOYAGE OF 11. M.S. CHALLENGER. 



of EiqjJicmsia, and, as it cannot reasonably be supposed to have escaped the attention of 

 Dana, I have deemed it advisable to refer the animal to one of the four species described 

 by that author. Of these, the species Euphausia jicllucida is the one that would seem 

 to agree best with the present form, for which, accordingly, I propose to retain the 

 specific appellation first suggested by Dana. That the Euphausia miillerl of Claus is 

 identical with the form here treated of is undeniable, and the form described by myself 

 as Tliysanopoda hidentata unquestionably also belongs to the same species. 



Description. — The usual length of the adult female is 10 to 15 mm., that of the male 

 somewhat less ; but there are a few specimens in the collection that reach a length of 

 17 mm. 



The form of the body (see PI. XL figs. 1, 2, 4) is rather slender, and, as usual, 

 somewhat compressed throughout, with the tail about twice the length of the anterior 

 division. 



The carapace has the anterior part distinctly keeled above, and jutting forth as a 

 sharp-pointed rostral projection, reaching to about the middle of the basal joint of the 

 antennulje. Posteriorly it exhibits an almost rectangular emargination, the lateral 

 angles of which are produced into narrow sinuses, marking sharply off above the lateral 

 wings of the carapace, which are broadly rounded (see also figs. 5, 6). Immediately 

 superior to the lower margins on either side occur two small anteriorly pointing denticles, 

 the posterior of which is placed above the point of insertion of the fourth pair of legs, 

 the anterior above that of the maxillipeds. The antero-lateral corners of the carajiace 

 constitute at the side of the basal part of the antennae a very slight dentiform projection, 

 apparently corresponding to the antennal spine in other Podophthalmia. 



The caudal segments are powerfully developed, and quite smooth aljove, diminishing 

 somewhat both in height and breadth posteriorly. The epimera are rather large and 

 laminar, projecting considerably beyond the ventral face, and covering at the sides the 

 bases of the pleopoda. They all exhibit a comparatively uniform appearance, being 

 somewhat angular in shape, and pointing obliquely backward. The last segment is a 

 trifle more elongate than any of the preceding, and much narrower, without any trace 

 of epimera, l)ut armed at the end, beneath, with a compressed, tridentate, pectiniform 

 spine (fig. 3), placed immediately in front of the anal orifice. 



The eyes (fig. 7) are of moderate size, and pyriform, witli the cornea rather expanded, 

 and projecting on either side (see fig. 2). 



The antennular peduncle (PI. XII. figs. 1, 2) is about half as long as the carapace, 

 and nearly cylindrical in form ; it is more particularly distinguished by the basal joint, 

 having at the end above a conspicuous erect leaflet or membranous lobe. In most of the 

 specimens this lobe is divided into two acuminate lappets (fig. 3) ; but in some speci- 

 mens, though differing in no other respect from the typical form, these lappets are much 

 more numerous, forming a dense fringe along the free edge of the leaflet (fig. 4). 



