northern variety from the Hebrides and Shetland the glandular thickening at each
bristle-tuft is in some developed ventrally (in the preparations), so that four rows of
scutes appear to be present. The ventral surface is often thrown into prominent
transverse rugge, which do not correspond with the processes for th,e long hooks.
The body is dull yellow and semitranslucent, the intestine being visible as an
orange canal. Anteriorly the ventral scutes are pale, the uncinigerous processes are
pale yellow, the lateral glandular belt deep yellow.
The pale golden bristles slope outward and backward from setigerous processes
of considerable length anteriorly,- and which are bifid dorsallv, the longer process being
posterior, and the margin curves inward ventrally. The setigerous processes become
smaller in their progress posteriorly, and cease before reaching the tail, the process itself
showing only the longer posterior papilla, the shorter being indistinguishable. The
number of the setigerous processes seems to be variable, ranging from thirty-five to sixty,
and, whilst the anterior are conspicuous, the posterior are not easily observed. The
bristles (Plate CXXVII, fig. 1) are in two groups, a longer and a shorter. They
are widest at the pale base, and gradually diminish distally, where they taper to a fine
point, which is curved. The longer and stronger bristles are dorsal, the shorter and
less robust ventral. The shorter forms are much more slender, their tapering tips alone
projecting beyond the surface. A simple bristle with a faintly serrated edge is figured in
Plate CXXVII, fig. 1 a. In some of the stronger traces of wings are just visible.
The uncinigerous processes commence on the ninth setigerous segment as a low
elevation with a short row of hooks, which in outline differ from the typical forms in the
middle of the body, in so far as the base is shorter an d~~ pro portion ally thicker, and a
considerable elevation occurs on the anterior outline beneath the main fang. The typical
forms (Plate CXXVII, fig. 1 b) have an elongated base slightly turned up at the prow, a
posterior outline deeply indented above the basal process, an anterior outline with a slight
projection below the chief fang, and a somewhat convex inferior (basal) outline. The
main fang is proportionally large in comparison with the neck, and the tooth above it is
of moderate size. A feature of these hooks is that whilst in lateral view the prow is
narrowed toward the point, in a view from above the end of the prow is flattened and
chisel-shaped. The uncinigerous processes, which are somewhat prominent posteriorly,
continue to the end. The row of hooks is on the anterior face of the tip (Plate CXXVII,
fig. 1 c). In the large northern variety from Shetland and the Hebrides the base of the
hook is somewhat thicker posteriorly.
Habits.—Two occasionally thrust their bodies and tails into a fragment of the tube of
a Serpula, the anterior region and tentacles being free at the opposite end. When lifted
or irritated and often when put in spirit it breaks its body about the ninth bristled
segment, that is, behind the anterior glandular scutes, and in sea-water it pulls this
fragment actively about by aid of its tentacles. As G-rube pointed out, it is brightly
phosphorescent, and by simply blowing on the water in the shallow vessel containing it
phosphorescent streaks appear on all the tentacles, and the corner of the vessel is so
illuminated that its edge can be seen. On touching a Zetlandic example brilliant bluish
phosphorescence gleams on every one of the tangled tentacles—spreading in a stellate
manner around.
Reproduction.—A large example from Plymouth on March 11th had small ova in its
coelom.
Grube (1860), in his original description, gave this form ten pairs of setigerous
processes with capillary bristles and commencing on the second segment, but he added
that behind them were twenty-one pairs of short bristle-tufts—scarcely distinguishable.
The rows of hooks commence on the twenty-first segment and are about seventy-two in
number on each side. In his excursion to Trieste he at once observed the distinction
between this form and P. medusa.
In 1864 Claparède made a note on this group, which was brought into prominence
first by Milne Edwards in his Report of M. De Quatrefages’ observations to the Academy
of Science, Paris (on the AphUbines). In this communication the Swiss author described
two forms, viz. Aphlebina hæmatodes and A. pallida distinguished by coloration, the
structure of the hooks, and, as he thought, by the number of the bristle-tufts.
In 1875 Panceri gave a short description with figures of this species, the figure of
the anterior region and the tentacles representing the luminosity, though the purple is
perhaps too deep. He locates the phosphorescent elements in unicellular glands in the
tentacles and along the body.
Considerable variety seems to occur in the commencement of the tori ; thus Langerhans
(1880) gives a range from the fifth to the ninth, the latter referring to a specimen
with seventy segments. The segments with dorsal bristles range from twelve to thirty-
seven, also following mainly the size.. The number with stout bristles (Stiitzbursten) is
apparently always thirteen. He (1880) gives a recognisable figure of the anterior hooks,
though the posterior outline is rather long in proportion to the posterior projection, and he
has not noticed the slight eminence on the anterior outline just below the throat a process
better marked in the posterior hooks. It occurred at Madeira chiefly in the deeper water
and in fish-baskets. He gives twelve segments to the thoracic region and forty-four in all,
and three pairs of segmental organs, whilst the bristles are from twelve to nineteen pairs.
Parasites.—Brumpt1 (1897) found a curious Crustacean (Saccopsis Alleni) parasitic
on this species at Plymouth, and which is closely allied to Saccopsis Terebellidis, Levinsen.
Caullery and Mesnil2 also describe a remarkable form, Xenocoeloma brnmpti, which is
attached to another species of Polycirrus (P. arenivorus), but has a communication with
the coelome of the annelid, and a process from the intestine exists at its base. The
authors consider that Brumpt’s form has a similar connection.
3. P olycirrus caliendrtjm, Claparede, 1868. Plate CXXVII, figs. 8 and 8 a—hooks.
Specific Characters.—Cephalic region and tentacles as in P. aurantiacus, and show
the same colour and bluish or violet phosphorescence. Tentaculiferous surface often
elegantly pigmented. Body terebelliform, 3—10 cm. long, with a breadth of 2—4 mm.
Setigerous segments 34—70, and non-setigerous 28—75. Ventral scutes eight pairs,
besides the large anterior median one. Six pairs of orange segmental organs in the six
f Comp. Rend. Ac. Sc. Paris/ June 21sfc, 1897.
2 ‘ Compt. rend./ t. clxi, p. 642, 1915.