at the ventral edge, with short spinous regions having a marked dorsal curve, presenting
only a short knob, smoothly rounded, at the tip (Plate XL, fig. 30).
The dorsal cirri are stout, shorter than in M. castanea, brownish, and, in spirit, taper
from base to tip, a few short clavate cilia occurring on the surface. The ventral cirri
are slender and tapering, and only reach a little beyond the bases of the nearest bristles.
A few short cjavate cilia are present.
Habits.—This species is probably commensalistic on another form, probably an
echinoderm, but hitherto it has occurred at St-. Andrews only in the free condition, viz.
as thrown on the beach after storms.
Genus XIX.— H a l o sy d n a , Kinberg, 1857.1
Body linear-oblong; head continuous anteriorly with the bases of the median and
lateral tentacles. Eyes large. Palpi smooth. Nuchal collar with a prominent flap.
Segmental eminences distinct and the papillae long. Proboscis with twenty-two frilled
papillae along each border. Only two short, wide, and glandular gastric caeca'pass
forwards into the peripharyngeal space. Scales eighteen pairs, large, soft, and with a
frilled outer border, not covering the dorsum. Dorsal division of the foot minute, with
slender, simple, and finely spinous bristles. Ventral division rather long, with numerous
somewhat slender bristles with tips of varying breadths.
H a l o sy d n a g e l a t in o s a , M. Sars, 1860. Plate XXV, f i g . 5.
Specific Characters.—Head ovoid, pinkish, running into the bases of the lateral
tentacles. Transverse diameter greatest. Eyes large, furnished with lenses, close
together, the larger anterior pair on the lateral prominence, and the posterior close
behind. The median tentacle is long, smooth, and tapering, with a filiform tip, and the
lateral tentacles are also long. The tentacular cirri agree with the median tentacle in
length and structure. The palpi are of moderate length, and smooth. Most of these
organs are tinted pale madder-brown. Body elongated, bristled segments forty-
three, barred. transversely with pale greyish-brown belts between the pedicles for
the scales. The nuchal collar has a prominent flap, which covers the posterior part of
the head. Segmental eminence distinct, and the papilla long. The proboscis is characterised
by about twenty-two frilled papillae along each border in extrusion, and a
muscular fold at each side. Scales eighteen pairs, not covering the dorsum completely,
large, soft, and rounded, with a folded or frilled outer border in spirit. The outer region
is studded with minute trifid papillae, but the margin is quite smooth throughout. The
dorsal division of the foot is minute, with slender simple and finely spinous bristles. The
1 Kinberg, in his description of the genus, gives little to discriminate it from Lepidonotus except
the numerous elytra and the elongated body.
ventral division is rather long, and has a long cone for the spine superiorly. The bristles
are somewhat slender, with, the spinous region of varying breadth, the superior simple
and Ion», the middle and inferior broad and bifid. Dorsal cirri rather long, slender,
and smooth, with a slight swelling (and a dark belt),;J)^lpw the filiform tip. The ventral
cirrus does not reach the adjoining tip of the fleshy part of the foot.
. S ynonyms.
1820. Polynoe foliosa, Savigny. Syst. des Ann., p. 23.-
1826. PoUno'e „ Risso. L’Europ. Merid., 414. .
1834. Polynoe „ Audouin and Edwards. Annel., 89.
1835. „ ’ gelatinosa, Sars. Beskr. og Iagtt, p. 63, Tab. 9, fig. 25.
1851. „ foliosa, Grube. Pam. d. Ann., 37.
1853. Aphrodita cirrosa, Dalyell. Powers Creator, ii, 164, pi. xxiv, f. 1 and 2.
1858. Halosydna gelatinosa, Kinberg. Preg. Eugen. Resa, Zool., p. 19, Tab. 5, fig. 26.
1860. Polynoe gelatinosa, Sars. Christ. Vid. Selsk. Forhandl., 1860, p. 58.
1865. „ „ . De Quatrefages. Ann., i, p. 249.
„ Lepidonotus imbricatus, Bail'd. Johnston’s Cat. Brit. Mus., p. 340.
,, Alentia gelatinosa, Malmgren. Nord. Hafs.-Annul., 81.
1866. Halosydna (Alentia) Jeffreysii, Ray Lankester. Trans. Linn. Soc., 25, p. 377, pi. li, figs. 12, 19
—21, 26, 27.
1867. Alentia gelatinosa. Malmgren. Ann. Polychast., 14.
1869. Halosydna gelatinosa, McIntosh. Trans. R. S. E., 25, p. 408, pi. xv, f. 6.
1870. Polynoe foliosa, Grube. Archiv f. Naturges., 1870, p. 288.
1875. Alentia gelatinosa, Ehlers. Annel.f Porcup.,’ op. cit., p. 34.
,, Halosydna gelatinosa, McIntosh. Invert, and Fishes St. A., p. 117.
1876. )> „ idem. Trans. Z. S., ix, p. 388.
1879. „ „ Tauber. Ann. Dame., 82.
1883. Alentia gelatinosa, Levinsen. Nord. Annul., 196.
1886. „ „ Langerhans. Zeit. f. w. Zool., 40, p. 251, Taf. 15, f. 6.
1888. Halosydna gelatinosa, De St.-Joseph. Ann. d. sc. nat. (7), v, p. 154, pi. vi, f. 6—21.
1891. ,, {Alentia) gelatinosa, Hornell. Op. cit., 237.
Habitat.—Everywhere distributed round British shores—from Shetland in the north
to the Channel Islands in the south. I t is generally found under stones and in crevices,
in laminarian roots between tide-marks, or in the valves of old shells in deeper water. It
ranges also to the Scandinavian coasts, as well as to Madeira. A small specimen, 13*5
mm. long, is described by Ehlers (1875) from the ‘ Porcupine ’ Expedition of 1869, from
the great depth of 1366 fathoms, on a bottom of fine mud. This, so far as my experience
goes, is a rare habitat, and no station or date is given—only the position of 54 54 N.
and 10° 59' IV.
Head (Plate XXVIII, fig. 11) with the transverse exceeding the antero-posterior
diameter, so that it forms anlivoid. Anteriorly the prominent base of the median
tentacle takes origin between the lateral lobes, and thus-well within the anterior margin,
while the bases of the lateral tentacles are continuations of the head, no peaks being
present. The eyes are proportionally large and prominent, and have lenses. The larger
anterior pair oooupy the projecting lateral region ; the smaller posterior pair are situated