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



females (one of which has been mounted on a glass slide) and a broken male specimen, 

 which I thouglit it right to dissect for anatomical purposes. The length of the adult 

 female is 10 mm., that of the male about the same. 



The form of the body (see PI. XXXV. figs. 1, 2) is much more slender and elongate than 

 in the typical species, and somewhat resembling that generally met with in the species 

 of Mysis ; the anterior division being very slightly dilated and about half as long 

 as the posterioi". 



The integuments exhibit a peculiar, and, as it were, scjuamous sculpturing, most con- 

 spicuous on the ocular pedicles and the basal parts of the several limbs. 



The carapace is comparatively small and narrow, contrary to what is found in the 

 typical species, not nearly covering the whole surface of the trunk, two segments of wliich 

 are exposed behind. It has, moreover, the posterior edge evenly emarginate in the 

 middle, and tapers anteriorly in such manner that its most anterior part does not exceed 

 in breadth the first caudal segment. The frontal margin juts out in the middle between 

 the eyes as an acute triangular projection, and forms, moreover, on either side, a similar 

 triangular lobe, projecting between each of the eyes and the base of the antennse. The 

 antero-lateral corners (see fig. 3) are rather broad and acuminate at the tip, and the 

 inferior margins of the carapace form at the side of the oral parts a very conspicuous sinus. 



The tail is rather slender, cylindrical, though slightly tapering posteriorly. The first 

 segment exhibits in the female, as in the preceding species, on either side, a narrow 

 elliptical vaulted plate or epimeron, and the last segment is rather elongate, about as long 

 as the two preceding segments taken together. 



The eyes are much narrower than in the preceding species, alnaost cylindrical, with 

 the cornea scarcely at all expanded, and not fully occupying the outer half of the eye. 

 The ocular pigment is of the usual dark hue. 



The antennular peduncle (fig. 4) is less robust, with the second joint quite of a 

 normal form, the last regularly cylindrical, scarcely at all dilated at the end. The outer 

 flagellum has a similar lamellar expansion at its base to that of the typical species, and 

 the male appendage would also seem to be quite similar. 



The antennal scale (see fig. 5) exhibits an appearance very nearly agreeing with that 

 in Anchialus typicvs, but is a trifle larger, having the denticle of the outer corner 

 distinctly developed, as also the marginal setse much coarser. A suture is seen to run 

 across the scale in close proximity to the inner corner, marking off" an obtusely triangular 

 terminal articulation, to which seven of the marginal setae are affixed. The proximal 

 part of the flagellum projects, as in the preceding species, considerably beyond the scale, 

 but has the terminal joint comparatively larger than in that form, and the basal spine 

 would seem to be somewhat smaller and quite smooth. 



The oral parts, though developed upon the same type as in the preceding species, 

 still exhibit in their structural details well-marked specific differences. 



