206 THE VOYAGE OF H.M.S. CHALLENGEE. 



anterior part tliau is the first caudal segment. The cervical impression is well marked, 

 thouoh not particularly deep. The frontal margin juts forth in the middle between the 

 eyes as a narrow triangular lappet, sharply pointed at the tip, Ixit not very prominent. 

 The antero-lateral corners of the carapace are obtuse-angled, and but slightly produced. 



The caudal segments are simple cylindrical and taper very slightly posteriorly, the 

 anterior five about equal in length, whereas the last segment is somewhat more elongate. 



The eyes are very large, pyriform, with the cornea considerably expanded, and 

 occupying the greater part of the eye. The ocular pigment is of a dark black colour. 



The antenuuLir peduncle is rather slender, almost half as long as the carapace, 

 and has the last joint in the female simple cylindrical, in the male (see fig. 4) slightly 

 dilated, and about as long as the basal. The male appendage is rather large, but only 

 slightly projecting in front of the peduncle, connate, as it is, with the lower face of the 

 terminal joint to its very base (see fig. 5). On removing the numerous fine hairs, with 

 which this appendage is clothed, the latter nre found to originate from a narrow band 

 doubled upon itself along the whole lower face of the appendage (fig. 5). Of the flagella, 

 the outer is much more elongate than the inner, and provided along its proximal part 

 with a row of delicate curved sensory bristles. 



The antennal scale (fig. 6) does not quite reach the tip of the antennular peduncle, 

 and exhibits a very narrow, linear form, about five times as long as broad. The outer 

 edge is perfectly straight and naked, terminating with a small dentiform projection. 

 The apex is somewhat obliquely truncate, with the inner corner slightly projecting. The 

 flagellum does not attain the length of the outer antennular flagellum, and has the 

 proximal part, or peduncle, shorter than the scale and very slender, with the middle joint 

 by far the largest, and the last exceedingly small. 



The anterior lip (see fig. 7) is produced anteriorly as a spiniform projection, similar to 

 that occurring in the genus Anchialus. 



The posterior lip does not exhibit any peculiarities in its structure. 



The mandibles (see fig. 7) are of moderate size, with the armature of their cutting 

 edges (fig. 9) perfectly agreeing with that in the other species of the genus, and rather 

 difiering from that in most other Mysidans. Thus, the molar protuberance forms 

 merely a simple conical process, without any trace of the usual fluted surface. The palp 

 (see fig. 7) has the middle joint considerably expanded and laminar, whereas the last joint 

 (fig. 8) is comparatively narrow, with a dense row of ciliated bristles along the posterior 

 half of the inner edge. 



The first pair of maxillae (fig. 10) exhibit quite a normal structure. 



The second pair of maxillaj (fig. 11), on the other hand, are highly distinguished by 

 the absolute want of the posterior masticatory lobe, only two such lobes being found. 

 The palp is very fully developed, with the terminal joint rather large, oblong, and not 

 incurved. The exognath is comparatively small and elliptical iu form. 



