REPOKT ON THE ANNELIDA. 
505 
somewhat flattened, and excavated by a median depression. The usual fissure proceeds 
forward in the central line to the thoracic division, and it shows only a slight bend to 
the right in the two anterior abdominal scutes. In the preparations the ventral scutes 
are (transversely) very wide and (antero-posteriorly) very short. A dark pigment-speck 
exists at the commencement of each uncinigerous row. 
The cephalic collar originates as a V-shaped structure dorsally, the inner leg of the 
V being less prominent and running as a slight ridge along the sides of the median 
groove forward to the base of the branchiae. The collar proper commences in front of 
the first bristle-tuft, and, somewhat within it, proceeds rather more than a third of the 
distance downward, where a break or fissure occurs, and ends in two large broad lappets 
on each side of the median line. In the preparation the collar still remains of a rich 
purple. 
The branchiae are arranged in two spiral tufts of the same fine purple colour, mottled 
here and there with pale streaks. Their number is very large, and in this respect 
they present a decided divergence from Schmarda’s form, which is described as having 
but twenty-one on each side. It is not easy to estimate the exact number, but they must 
be considerably more than a hundred. The radioles are comparatively slender and 
flexible, and are furnished at intervals with pairs of small external appendages 
(PI. XXXIXa. fig. 7), which do not occur at the base in the intervals between the 
radioles, as in the former species ; moreover, they become longer and somewhat spathulate 
or auricular (as indicated in the figure) toward the tip, which has a short, bare filiform 
termination. The pinnae are very numerous but not proportionally long, and gradually 
diminish distally, without, however, showing the truncated nodular or papilliform stages, 
as in some allied forms. 
The tentacles are short, stout, acutely pointed processes placed on each side at the 
anterior end of the dorsal cephalic furrow, and their tips only extend a little beyond the 
separation of the radioles from the basal web. They are slightly grooved on the ventral 
surface. 
The thoracic region possesses the ordinary eight segments, and the approximation of 
the bristles of the opposite sides anteriorly gives a marked curvature to the outline of 
the dorsum. The bristles are comparatively uniform in structure, the differences between 
the dorsal and ventral types being less pronounced than usual, some of the dorsal being 
longer and narrower, and some of the inferior shorter and broader than the intermediate 
type figured (PI. XXXIa. fig. 7). The tips of the posterior bristles do not show much 
elongation, while the wings are somewhat broader. 
The anterior hooks (PI. XXXIa. fig. 8) have remarkably fine serrations above the 
great fang, appearing, indeed, under a low power to be almost smooth. The prow 
or anterior projection is moderately developed. The posterior basal process is com- 
paratively short, truncated and bent downward at the tip. The dorsal outline curves 
(ZOOL. CHALL. EXP. — PART XXXIV. — 1885.) LI 64 
