S ynonyms.
1860. Polycirrus aurantiacus, Grube. Arch. f. Naturges., Bd. xxvi, p. 110, Tab. iv, f. 8.
1861. „ idem. Ausfl. Triest, pp. 78, 128, 149, Taf. iv, fig. 8.
1864. „ ,, idem. Insel Lussin, p. 89.
„ Aphlebina pallida, Claparäde. Glanures, p. 25, pi. ii, fig. 2.
1865. Apneumea aurantiaca, De Quatrefages. Annel., t. ii, p. 383.
1869. Polycirrus aurantiacus, Grube. Mitt. St. Yaast, etc., p. 38, Abhandl. Schles. Gesell., p. 105.
„ „ „ McIntosh. Trans. Roy. Soc. Edin.j vol. xxv, p. 424, pi. xv, figs. 18
and 19.
1875. „ ,, Panceri. Atti R. Accad. Sc. Napoli, p. 7, Tav. ii, figs. 4—7:
1880. „ „ Langerhans. Zeitsch. f. wiss. Zool., Bd. xxxiv, p. 108, Tab. v, fig. 23.
1884. » „ idem. Ibid., Bd. 1, p. 266.
1885. ,, ,, Carus. Fauna Medit., i, p. 267.
1893. „ ,, Marenzeller. Polych. Grund., p. 34.
„ „ „ Lo Bianco. Atti R. Accad. Sc. Nap., vol. v, No. 11, p. 60.
1894. ' „ „ De St. Joseph. Ann. Sc. nat., 7s ser., t. xvii, p. 239.
1897. „ „ Brumpt. Compt. Rend. Acad. Sc. Paris, 21 June, 1897 (Crust. Parasite).
1904. „ Journ. M. B. A., vol. vii, p. 229.
1909. „ „ Fauvel. Bull. Inst. Ocean., cxlii, p. 38.
„ „ „ idem. Ann. Sc. nat., 9® ser., t. x, p. 209.
1916. „ „ Caullery. Bull. Soc. Zool. France, t. xl, p. 242.
1917. „ „ Rioja. Anel. Poliq. Cantab., p. 60.
„ Hessle. Zool. Bidr. Uppsala, Bd. v, p. 226.
Habitat.—Abundant under stones and in crevices of rocks between tide-marks and
also dredged on the oyster-beds at St. Peter Port, Guernsey ; occasionally in a tube of
sand inside the valves of Tapes. It sometimes occurred in masses of GelLepora dredged in
15 fathoms in the same region, but it does not appear to bore. Not uncommon in similar
regions in Herm. Both this and P. haematodes haunt the mud under stones in the Channel
Islands. Dredged in the Minch off Lochmaddy, and abundantly amongst the tangle roots
obtained by the “ dreg” in Bressay Sound, Shetland; St. Magnus Bay; Symbister
Harbour; in 50 fathoms off Balta (J. G. Jeffreys).
Mediterranean and the Adriatic (Grube) ; common in colonies amongst littoral Balani
at Naples (Lo Bianco); shores of France, De Quatrefages, De St. Joseph; shores of
Cantabria (Rioja) ; Madeira (Langerhans).
The cephalic region has even more voluminous folds than in P. medusa, the plate
being frilled anteriorly as well as forming the two broad folds posteriorly, Moreover
dorsally is an indication of a collar in the shape of a smoothly rounded ridge. The whole
is occasionally spread as a wide border to the oral region, which thus assumes the form of
a shallow funnel.. When viewed from the dorsum the slight dorsal collar runs on each
side and bends downward behind the projecting fold of the anterior arch, and it
sometimes happens that a median fold in front divides the tentacles into two symmetrical
series after the manner of Phoronis. The entire outer surface gives origin to
the dense series of dull yellow tentacles which form a seething mass of threads—slender,
flattened and fusiform. Each tentacle extends even to a greater degree than in
P. haematodes, becoming paler when stretched though still retaining a trace of the
yellow hue. Their extensibility and elasticity are remarkable, and the thinnest strand
presents a minutely cellular appearance with a central streak. The smaller and shorter
tentacles occupy as usual the edges of the posterior lobes, so that when the flaps
are adpressed they are close to the fissure leading to the mouth. As in P. haematodes the
tentacles form an inextricable mass in a vessel, enclosing other annelids, fragments
of shells, Balani and mud. When much stretched, the tip, which is generally the
widest part, is yellowish, the attenuate region below it being pale, and the intermingling
of these hues, especially against a dark background, is striking.
A specimen of moderate size can stretch its tentacles 3 or 4 inches, the processes
being dilated at the tip but of extreme tenuity toward the base, and the corpuscles
of the coelomic fluid are observed in the centre. Moreover, besides those in a straight
line many tentacles form curves, a coil or two or! a series of coils like a corkscrew, and
then suddenly these are drawn rapidly towards the cephalic region as if they were
sliding along one of the attenuated tentacles in the line of retraction. By aid of these
organs the annelid pulls itself along the bottom of a vessel, its body meanwhile remaining
in various coils, and apparently taking no part in progression. Having reached the
corner of a glass vessel it seemed to be contented—keeping up a constant movement of
body and tentacles, apparently for respiratory purposes, the tail being frequently thrust
beyond the central mass as a finely tapered region with a slight swelling at the tip, whilst
waves of dilatation occured at intervals, and the numerous and closely arranged uncini-
gerous processes projected like lateral spines or serrations. In retracted tentacles the
grooves were evident.
Instead of the single large first oral scute of P. medusa, this species has a tongueshaped
median glandular process, the edges of which are free, and the anterior border
runs smoothly forward to the mouth. In one example this process was bifid posteriorly
whilst a small area was cut off anteriorly, the whole being symmetrical. It may represent
the first scute.
The body resembles that of P. medusa, and like it is in the preparations almost
always coiled; only the tail is generally more tapered than in the species mentioned.
It is rounded dorsally and often dilated anteriorly, grooved ventrally, and terminating
posteriorly in the anus, which may have a simple crenate margin, though it generally
shows a more prominent ventral papilla, occasionally a smaller dorsal papilla or both
a dorsal and a ventral. Probably much depends on the condition of the region with
regard to reproduction. In the preparations dilatations occur dorsally both in the
region of the scutes, and, when this part is contracted, in the region behind.
The ventral scutes commence with the large median tongue-shaped one already
mentioned, and laterally are two small scutes each of which abuts on a bristle-
process (first and second). Each of these has its inner edge bevelled by the
encroachment of the median scute. Six pairs of scutes follow, for the deep median
furrow separates the respective sides. A rounded glandular scute of small dimensions
is conspicuous on several of the succeeding segments, which have a longer anteroposterior
diameter than those in front. A glandular belt also envelops each bristle-
tuft anteriorly, and is continued, though less distinctly, posteriorly (Plate CXX, fig. 4),
where the uncinigerous processes are more evident than the setigerous. In the large