Length one and a half to one and three quarters inches.
Head (Plate XXVIII, fig. 5) somewhat like that of Harmothoe imbricata in outline,
only the anterior peaks are less acute and the widest region is further forward, so as to
give the head a more distinctly ovate form. The posterior pair of eyes are nearer each
other, and the larger anterior pair are more visible from tho dorsum. The median tentacle
is of moderate length, with just a trace of a dilatation below the filiform tip, and furnished
with sparsely distributed short clavate cilia. The lateral tentacles are short and tapering,
and have a very few of the same small clavate cilia. The palpi are smooth under a lens, but
show very minute papillaa under a high power. The toughness and extensibility of these
organs are well seen in this species. The tentacular cirri also show a trace of an enlargement
below the filiform tip, and have sparsely distributed short clavate cilia. These and
the tentacles are sometimes tinted brownish.
Body rather elongate, slightly tapered in front and more distinctly from the anterior
third backward, and having thirty-eight bristled segments. In some the dorsum is
pale, but in others, as in the drawing, it is barred with brown throughout, the pattern in
each segment posteriorly being beautifully defined. The under surface is pale. The
segmental prominence is distinct, and a considerable papilla projects between the feet.
The body terminates in two long, tapering, caudal styles.
The pre-gastric caeca agree with those in Harmothoe imbricata.
Scales (Plate XXXIII, fig. 5) fifteen pairs, entirely covering the dorsum; the first
pair rounded, the succeeding reniform-ovate. The anterior cling somewhat firmly to the
pedicles. The surface is densely covered with minute chitinous-papillaa (really minute
spines), so that it appears like shagreen under the microscope. Towards- the outer
border a few short clavate cilia project from the edge and also appear on the neighbouring
surface. The scales are comparatively thin, but of considerable toughness.
They increase in size posteriorly. Their colour is often pale, but in some it is brownish,
and in the coloured figure the papillae of the scales and other organs are ipfested by a
blackish parasitic growth which greatly alters the aspect.
In two fine examples procured after a storm on the west sands at St. Andrews
(E. M.), the scales had a broad marginal belt in the exposed portions, leaving a large
ovoid pale region in the middle. The dorsum besides was richly tinted with brown.
Coloured examples, indeed, are more common in the north than in the south.
Many Loxosomse occur on the scales of a specimen from the Moray Frith.
Feet.—The first foot has a very strong spine and a group of about four short
bristles of the dorsal type.
In the second foot the dorsal bristles form a dense tuft, the closely arranged spinous
rows and the rudimentary bare portion at the tip being diagnostic, though the bristles
have not attained the length of the typical forms. The ventral division consists of a
series of slender bristles with long, tapering, spinous regions, and simple slender tips.
Moreover the shape of the foot is peculiar, the dorsal division in lateral view forming a
high crest, while the ventral is distinguished by its long, acute cone projecting
horizontally above the spine.
In the third foot the bifid condition of the ventral bristles is more evident, and the
dorsal are longer. The conical process of the ventral division is larger. By easy stages
the typical foot (Plate XXX, fig. 12) is soon reached, showing a ventral division
terminating superiorly in a long conical process above the spine. The dorsal bristles
(Plate XL, fig. 5) spring from an oblique eminence, and are characterised by their great
proportional length, slight curvature, and gently, tapered extremities, those next the
body having somewhat blunt tips, those next the ventral being more acute. The tips of
the blunt forms scarcely show a bare portion, the rows of spines being continued to the
tip, but the acute bristles next the ventral have a minute bare portion which sometimes
presents a slight keel. The spines are short and the rows very close, so that the bristle
is at once distinguished from that of Harmothoe imbricata, irrespective of the length of
the tip. The, ventral bristles are numerous, long, and slender, the spinous region of the
upper forms being of great length, the rows closely arranged, and the spines rather
short. The tips are bifid, the terminal hook is small, and the secondary process makes
a very slight angle. Moreover the smooth region is remarkably short, the spines
passing up to the fork (Plate XL, fig. 6). Both sets of bristles are of a lustrous pale
yellow, almost like those of Ghloeia, and. thus afford a contrast with thé dull straw-
coloured organs of Harmothoe imbricata. In shape the ventral lobe of the foot is
peculiarly pointed, the base being bevelled superiorly, and with a projecting fold
inferiorly.
In the terminal feet the dorsal bristles are few in number, more slender and
elongate, the tip pointed, and the rows of spines distinctly wider. . The ventral are also
few in number, slender, with long, tapering, spinous regions, and attenuate, simple tips.
The dorsal cirri present scarcely any enlargement below the filiform tip, are pale
throughout, have short clavate cilia sparsely scattered over the surface, and they are
longer distally than proximally. The ventral cirri are long subulate organs, the tip
extending considerably beyond the bases of the bristles.
The dorsal bristles are the seat in some of a peculiar blackish fungoid growth, as
indicated in the coloured figure. This minutely granular structure finds a suitable site on
the spiny ridges of the dorsal bristles, and thus both shaft and tip are barred with
black in a characteristic manner. This coating can readily be removed by pressure, and
no evident change is apparent in the bristle. It is rendered brown by hydrochloric acid,
while caustic potash does not seem to alter it much. This growth also affects the
spinous region of a few of the ventral bristles.
Habits.—This is another example of the fact that species which frequent off-shore
waters in the north are found between tide-marks in the south, as in the Channel
Islands. I t is a comparatively hardy form, and the example from which the coloured
drawing was made lived for weeks in the centre of Perthshire, though towards the
termination of the period many of the ventral bristles were shed.
After careful consideration this form has been associated with Savigny’s Polynoë
setosissima.
Audouin and Milne Edwards (1843) assigned forty segments to this species, and
they and Savigny found their examples at Havre.
De Quatrefages (1865) included it under his fourth group, in which the body is more
or less elongated, and covered by fifteen pairs of scales. He describes the species as
provided with a simple triangular head; the median antenna large, about as long as the