22 
THE VOYAGE OF H.M.S. CHALLENGEE. 
off in such an animal, and the anal region accommodates itself with such ease to the 
altered circumstances, that little weight is to be put on this feature. Both dorsal and 
ventral surfaces are somewhat convex, the former being marked transversely with the 
segment-lines and slightly corrugated throughout ; the latter showing the segment- 
junctions even more distinctly, each being coarsely rugose, and having a median 
longitudinal furrow. The three segments behind the mouth are somewhat smoother. 
For so large a body the head seems disproportionately small. In front the snout, 
which consists of the anterior border of the buccal segment and corres]3onds to the 
prominent anterior labial folds in Euphrosyne and Chloeia, bears two tentacular cirri 
(palpi) which are larger than the succeeding processes of the kind. They are conical 
and of a ferruginous hue from base to apex. The next organs are the two cirri situated 
at the anterior border of the slightly differentiated cephalic region, which indeed appears 
at this part to be continuous with their buccal division. Their bases are separated by a 
slight interval, and each has a basal bluish segment, and a terminal conical ferruginous 
division. Immediately behind is the small tongue-shaped caruncle, which springs nearly 
in a line with the anterior border of the first bristle-papilla, and terminates in a groove 
in front of the posterior border of the first body-segment. The organ is attached along 
the middle throughout its entire length, but is free at the edges. Its upper surface is 
quite smooth, or in some slightly wrinkled, and the whole is somewhat darker (bluish- 
black) than the surrounding parts. In some the edges are of the latter shade, while the 
central region is of the ordinary bluish colour of the dorsum. It is deeply cordate in 
front, and at the termination of the sinus bears a short ferruginous conical process — the 
median tentacle. The mouth opens inferiorly at the anterior border of the third body- 
segment, and from the oral aperture two well-marked folds (corresponding with sjDecial 
thickenings in Chloeia) run forward to the anterior prominence of the snout which bears 
the cirri. These folds are wide in front, narrow behind. Two additional plaits pertain to 
the second segment, and another to the first. 
The branchiae commence on the third body-segment, and have the form of dense 
arbuscles, the first being nearly as large as any of the succeeding. So dense are they, 
indeed, that Pallas likened them to the cotyledons of the ruminant chorion. Each 
arbuscle consists of six or seven main stems springing from a common base, and divi din g 
somewhat dichotomously into a dense bush of filaments. The outer stems have shorter 
terminal processes, the inner possess both longer stems and longer terminal processes. 
The latter are ferruginous in colour throughout, while the stems and branches are of the 
usual bluish tint. The tuft is situated close to the base of the dorsal bristle-papilla, and 
somewhat to the inner or dorsal side. The larger (dorsal) branches of the arbuscle 
envelop the bristle-papilla in the preparation, so that only a small portion of its anterior 
and inferior region is bare. The branchiae are continued to the tip of the tail. Towards 
the posterior fourth of the body, as Pallas says, they meet on the dorsum, again separat- 
