ventral muscles divides the surface into a median and two lateral regions, the former'
having the farrows of the segments from side to side, the latter only at the edges, as the
muscular region is smooth. In some the dorsum is rendered dull ochreous by a deposit
of this colour in the grooves, the ridges being pale, and the same ochreous coating is
found on the under surface and inner edge of the scales. A solution of potash makes no
change, but dilute hydrochloric acid slowly removes the deep orange colour and renders
the granules invisible.
Posteriorly the body terminates in two symmetrical basal processes which bear cirri
longer than on other parts of the body, but having the same structure and coloration.
The anus is a small aperture (especially when contrasted with that of L. clava) opposite
the posterior border of the penultimate pair of feet.
Proboscis.—The exserted proboscis shows a series of eighteen1 papilhe around the
margin. These vary somewhat in shape, being conical or hatchet-like in outline, with a
terminal process and a beak, or in .shape somewhat like a dactylozoid of Millepora. All
have a trace of dark pigment in the centre. The horny teeth alternate, so that the
upper go slightly to the right of the under pair. The horny ridge on each side of these
organs will also subserve the functions of division of food.
Three caeca from the gut pass obliquely outward to the dorsal wall, the fourth being
nearly transverse. They are larger and less alternate than those of Harmotho'e, and of a
darker yellow hue. They are richly glandular, with deep yellow granular cells or masses
here and there, giving a minutely dotted aspect to the surface. Their tips present only
a short lobe in addition to the terminal one. Their arrangement and aspect thus differ
from those of Harmotho'e.
The food in the intestine consists of sand-grains, fragments of crustaceans, and
other debris.
Colour.—The dorsum is of an uniform brownish-grey hue in some, or with a lighter
area on each scale, the inner edge of which has, moreover, a dark brownish spot.. In
others the central pale area has a nearly complete brownish ring encircling it. In
those from the stomach of the cod the papillas, especially on the anterior scales,
retain their colour, so that they are conspicuous. Again, in examples from Guernsey
and Shetland the larger bosses on the anterior scales were of a reddish amber hue, while
some young specimens were mottled with reddish brown or madder brown. Those from
the Gulf of St. Lawrence had bristles of a dusky golden hue, and the papillas of the
scales were also darker. Under surface iridescent, bluish pink anteriorly, and pinkish
posteriorly. In some from Shetland (Bressay Sound) the bases of the posterior feet
ventraily had a well-marked touch of blackish pigment situated between the nephridial
processes and extending from the tail fully a dozen feet forward, and a series of dark
touches in the median line in each segment, a pale longitudinal streak, however, cutting
each into two.
■ Scales. —The first pair of scales are rounded, and, like the two or three following,
have large horny tubercles, the darker colour in some specimens making them very
prominent, and each is ciliated for more than half its circumference. The next pair are
reniform, and the succeeding are more or less ovoid. The brownish horny tubercles or
1 De Saint-Joseph says sixteen.
bosses project as blunt points from the surface in profile. The scales (Plate XXXII,
fig. 1) increase in size posteriorly, the general shape being ovoid, though they are wider
at the ciliated posterior border. The under surface is smooth and iridescent, and shows
the pear-shaped scar for the attachment of the pedicle. In some, however, the surface
presents the ends of fibres torn from the pedicle, and this sufficiently explains why
some are readily removed, and others require separation with a knife. All the scales
considerably overlap each other, and cover the dorsum entirely. The simple filiform
. cilia which occur on the edge appear to preserve the same relative length from the first
to the last, and they are often coated with a muddy deposit, and have various microscopic
growths. So far as can be observed, these cilia are simple and nearly cylindrical
processes with a smoothly-rounded tip, and a median streak, as if from an axis of
differentiated tissue. Under the action of potash the scale becomes coarsely granular or
areolar, the areas of the bosses or blunt spines being characterised by a more regular
arrangement of granular cells.
In young examples, barely 3 • mm. in length, the scales have a few large tubercles,
and the cilia are hirsute, with grains of various kinds, besides being proportionally larger
than in the adult. De Saint-Joseph found that in a small example, 5 mm. long, the
scales were covered with Grammatophora marina.
In general structure the scales have externally a more or less chitinised cuticular
layer, with a cellular (columnar) coat beneath, a fibrous stroma passing between the
dorsal and ventral layers, and finely-branched nerves, from the ganglionic mass at the
scale tubercle, terminating in end-organs. The external surface has various chitinous
tubercles or processes, and the edge has cilia.
The chitinous tubercles and spines are placed in the thick cuticular layer, and the
larger are hollow in the centre, and the surface is roughened with small processes so that
they look honeycombed. This is due to the minutely nodular condition on the surface,
and not to scales, as Baron de Saint-Joseph1 states. When the dark brownish (Algoid ?)
coating begins to cover their surface, the “ bosses ” present a reticulated appearance,
since the parasitic growth first invades the hollows between the minute tubercles.
Pigment occurs in the cellular layer beneath. The scar has a complex series of muscles,
some of which pass into the hollow of the organ. The majority of the muscular fibres
are fixed to the scale-tubercle. As Prof. Haswell3 says, they serve in the Polynoidse for
protection, for the production of phosphorescence, for sensation, and in certain forms
_for incubation.
The scales readily separate in ripe examples, and the under surface is as finely
iridescent as in Haliotis. Captured specimens reproduce their scales. Thus in a month
they reach about a third the size of the original organs, but are pale, and their translucent
condition shows that the tips of the papillae are minutely nodular.
Many parasitic structures occur on the scales, but none more beautiful than
Carchesiumt the long tufts of which resemble, under the lens, miniature zoophytes.
Occasionally examples occur with a deep orange coating on the under surface of
the scales and the dorsum of the body. In structure it is minutely granular, as in the
darker (blackish) ooating on the bristles and. other organs.
1 'Ann. des Sc. Nat./ 8th ser., v, p. 231. 3 'Ann. Nat. Hist./ 8th ser., x, p. 241, 1882,