The segmental papilla is directed between the feet, and is in the form of a slightly
tapered process of some length. The northern forms agree with the British in regard
to this structure.
Posteriorly, the body terminates in two elongated caudal styles, which have a
similar structure to the cirri.
Proboscis.—When extruded, the organ shows on each edge nine terminal papillse
similar in shape to those of Lepidonotus. The horny jaws appear to resemble those of
the genus named, and they are acutely pointed.
Two long, slender casca pass forward into the peripharyngeal space.
/Scales (Plate XXXI, fig. 1)—fifteen pairs. The first pair are somewhat
circular and ciliated all round, the inner and anterior margins having short
and somewhat clavate cilia, the rest being densely covered with similar cilia, which,
as usual, are often thickened by parasitic growths. The surface has numerous
small horny papillm scattered over it, so that it is finely spinous. Such a scale,
however, is in contrast with the Arctic examples or those from the Gulf of St.
Lawrence, Norway, and Finmark, in which the sharp brown spines form prominent
features in every’scale of both large and small examples. Bifid tips also occur on many
of the spines, as mentioned by Malmgren. It is not a question of size in regiard to this
difference between the British and the other examples, for in large representatives
from the west of Ireland the same features are present as in the other British specimens.
Moreover, the cilia are more prominent in the northern forms. These features, however,
by no means indicate specific difference, for the general characters remain diagnostic.
The condition of the scales of the British examples is more like that of Gattyana
Amonsdeni, Mrgn., though the spines are not so visible under a lens.
The scales of some have grains of sand and mud attached externally. Old and fine
specimens have a dull olive hue on the dorsum, while the edges are flanked by the paler
bristles and cirri, which are often, however, so coated with parasitic algas and other
structures, and grains of sand, that their normal hue is obscured. The scales of the large
examples from the tubes of Amphitrite have a finely-streaked appearance from the dark
growths on the spines. .
Colour.—Dorsum of a pale yellowish-brown or sandy colour, the anterior scales
being somewhat darker. In a considerable number (the majority of those tossed
on shore at St. Andrews) a dark greyish-brown spot occurs at the point of attachment,
and these form a somewhat regular row along each side. The prominent spines of the
Arctic examples are brownish. The same dark spot at the point of attachment is present
in some of these, and a dark touch at the inner border of each scale, so that an
interrupted double band occurs along the middle of the dorsum. Tentacular processes
pale. Head deep pinkish red, or only between the posterior eyes. In some the central
process of the nuchal collar is bordered with dark pigment.. Under surface pale,
iridescent. Bristles pale yellow.
None of the British examples appear to show the dark median band of the dorsum
from the nuchal fold backward, with fainter touches of colour in the median depressed
parts of each segment to the tail, where darker pigment again appears, which
characterises some Arctic examples (Godhaven Harbour). Flecks of pigment are also
seen along the mid-dorsal line even when no distinct band is present anteriorly and
posteriorly.
Feet.—The tentacular cirri agree with the median tentacle. The basal region has the
usual small tuft of serrated bristles (corresponding to the dorsal) with a spine. They
are somewhat short and rather stout bristles, with rows of short spikes towards the tip.
In the second foot the dorsal bristles are shorter and more roughly spinous than in
the typical foot. The latter is probably partly due to their shortness and greater curvature.
On the other hand, the ventral bristles have much more elongated tapering tips than in
the typical foot. The ventral cirrus has a few short clavate papillae throughout the whole
series.
The third foot presents a considerable change in the dorsal bristles, which now show
the strong series with curved, serrated tips next the body, and the slender series with
tapering tips adjoining the ventral division. The dorsal cirrus is somewhat shorter and
thicker than in the fully developed foot. Both shafts and tips of the ventral bristles are
still much more slender than in the average foot.
In the fourth foot a near approach to the condition in the typical foot occurs,
though both dorsal and ventral bristles are more slender.
In the typical foot the dorsal division is bluntly rounded and turned upwards (Plate
XLII, fig. 27), the spine, which is sheathed in skin, passing out as a slender process
towards the inferior edge of the bristles. The dorsal bristles are rather slender
(Plate XXXVII, fig. 18), have a long tapering tip, with rows of spines, the extremity
being hair-like. The ventral division, on the other hand, has a somewhat triangular edge,
the spine, which is sheathed at the base, and forms an independent process posteriorly,
passing outward at the apex of the triangle. The ventral bristles show tips increasing
in leno-th from below upward, the superior bristles (Plate XXXVII, fig. 16) having
more delicate tapering tips and more numerous rows of spines, while the tips are slightly
hooked, the intermediate series (Plate XXXVII, fig. 17) often having a slight enlargement
below the hooked tip. In large examples from deep water beyond St. Andrews Bay the
smooth tips of the ventral bristles are somewhat shorter and broader. In contrasting
these with the bristles of Arctic examples, the tips (that is, the region beyond the spines)
of the latter are longer, and the bristles, both dorsal and ventral, are in some cases rather
stouter. In the Arctic forms also the cilia on the cirri are somewhat longer.
In the posterior feet the tips of the ventral bristles again become elongated and the
shafts more slender. In the last foot, indeed, the tips are so attenuate that, leaving the
shafts out of sight, the curve of this region is almost the only distinction by which they
can be recognised. The ventral cirri also are more elongate.
A curious ochreous appearance occurs in certain forms from Godhaven, Greenland,
in which the tips of the dorsal bristles are covered with a minutely granular reddish-
brown deposit, probably derived from their surroundings. The same structure coats the
cilia of the cirri and scales.
The figure of the foot in Malmgren’s paper does not show the upper spine, and in
the ventral division the conical process for this structure is absent.
Parasites.—Loxosoma is not uncommon on the bristles and feet of the Arctic forms
and those from the Gulf of St. Lawrence.