prominence, posterior in front of collar. Median tentacle of moderate length, smooth,
as are also the lateral tentacles, tentacular cirri and palpi, which are of moderate length.
Body about § inch long, of thirty-six to forty-one segments, with madder-brown pigment
posteriorly on the dorsum, and more sparingly on the ventral surface. Segmental
eminences fairly developed, but without evident papillge. Scales, fifteen pairs, adherent,
smooth, with the exception of a small and somewhat triangular group of papillae at the
anterior curve in those of a reniform shape; variously bordered with madder-brown.
Dorsal bristles translucent, somewhat short, slightly curved, little tapered, and with a
rather abrupt point; spinous rows faint. Ventral bristles translucent, with short spinous
regions; fine rows of spines, a well-marked hook at the tip and a secondary process after
an interval.
'S ynonyms.
1868. Eunoa. Report Brit. Assoc., 1868, p. 387.
1876. Malmgrenia castanea, McIntosh. Trans. Zool. Soc., is,- 376, pL-lxvii, f. 15—19.
1886. Malmgrenia castanea, Harvey-Gibson. Verm. Liverp., 149 and 345.
„ Lsenilla castanea, Giard. Bull. Sc. Nord, i, 3.
1891. Polynoe (Malmgrenia) castanea, Hornell. Op. cit., p. 235.
Habitat.—Dredged by Dr. Gwyn Jeffreys off North Unst, Shetland, in 1867, in
90 and 96 fathoms, on Spgtangus purpureus, and again in 1868, attached near the
mouth of the same Echinoderm, living on a bottom of shell-sand in 85 fathoms, twenty-
five miles north-north-east of TTnst. The same veteran explorer of our seas found it in
80—125 fathoms, fifty miles west of Valencia, and in 110 fathoms, thirty miles west of
the Blasquet, south-west Ireland, in 1870. I t was also dredged off St. Peter Port,
Guernsey, in 5—7 fathoms, in 1868. Mr. Hornell procured a“ few on the same host
in the Liverpool district in 20—22 fathoms, and Professor Herdman at the Isle of
Man. The Royal Irish Academy’s Expedition of 1886 also procured a small example
in 480 fathoms. Professor Giardr found it on the shores of France on the same
Echinoderm.
Head (Plate XXVIII, fig. 15) somewhat like that of Lepidonotus and Halosydna in
so far as the anterior border of the head runs into the base of the lateral tentacles. The
head is pyriform, broad and rounded behind, and narrowed in front. A pair of large
eyes lie in front of the nuchal collar, and a still larger anterior pair in front of the
lateral prominence, looking forward and Qutward. They are thus separated by a
considerable interval, and in the preparations nearly occupy the corners of a square. A
trace of a lens appears in the centre of the anterior pair, which are only partially visible
from the dorsum. The smooth median tentacle is moderately developed, and has a slight
swelling below the tapering tip (in spirit). The lateral tentacles are short and subulate,
with brownish pigment above the base. The palpi are smooth and of moderate length.
The tentacular cirri have a similar structure to the tentacle, most being somewhat
fusiform in outline.
Body about | inch in length, and having from thirty-six to forty-one bristled
segments. In most of the preparations it is pale anteriorly, but marked with madder-
brown pigment on the posterior segments. The colour varies considerably. The
under surface of the body is iridescent pinkish. In some a considerable amount of
brown pigment occurs posteriorly on each side of the median groove, and on the
segmental eminences, the site of the papilla being indicated by a darker speck. On the
whole the body is rather firm and broad, tapering a little anteriorly and more so
posteriorly. I t terminates in two tapering caudal cirri, often of a deep brownish hue.
The segmental eminences are fairly developed, but no distinct elongation of the papillae
occurs.
Scales (Plate XXXIII, fig. 10), fifteen pairs, covering the dorsum, only a brief
portion of the tail being uncovered. The first pair are rounded, the succeeding reniform,
then ovoid, while the large posterior scales are irregularly quadrate. They are smooth
glistening organs under a lens. Under the microscope they present a somewhat triangular
group of papillae on the anterior concavity of the reniform scales, but in the
posterior scales these almost disappear. They are surrounded by a madder-brown belt,
with a tendency to the development of a denser portion in the anterior band. In
addition to broader marginal belts, the posterior scales have a general sprinkling of the
brown pigment. In some, especially those near the mouth of Spatangus purpureus,
all the exposed portion of the scale is tinted of a deep madder-brown. The scales
seem to adhere with considerable tenacity. The nerve-supply is similar to that in
Scalisetosus communis, but it is considerably obscured by pigment.
Feet.—In those examined only a spine occurred in the first foot.
In the typical foot (Plate XXX, fig. 5) the dorsal lobe is not much developed, forming
a small process from which the somewhat short bristles project. They are very
slightly curved, and taper a little towards the tip, which ends in a short point (Plate
XL, fig. 23). They are translucent, finely striated longitudinally, and with faint spinous
rows which go almost to the point. The dorsal spine projects in its sheath only a short
distance towards the lower edge of the bristle-bundle. The ventral bristles have slender
translucent shafts with a median axis, and striae distally as well.as in the spinous region.
The ordinary appearance of one of the superior ventral bristles is shown in Plate XL,
fig. 24, scarcely a trace of the secondary process being visible below the well-marked
hook at the tip, and it altogether disappears ventrally (Plate XL, fig. 25). In the
developing form the secondary process is clearly indicated. The spinous rows are
close, and leave only the short terminal region bare. In specimens from Valencia (southwest
of Ireland) this process is very distinctly seen, for instance, when the bristle is
slightly turned round (Plate XL, fig. 26). The secondary process is less marked in
specimens from the Ghannel Islands and Shetland, though indications are present in all.
In viewing the body from the ventral aspect the feet after the thirteenth become considerably
larger, and continue so till the thirtieth. This, as* in Harmothoe marphysse,
may be associated with reproduction.
The dorsal cirri are of moderate length, smooth, slightly enlarged towards the end
of the column (in spirit), and with a filiform tip. They increase in length (as usual)
posteriorly. The ventral cirri extend to the bases of the bristles, and are subulate and
smooth.
In a small example dredged at 480 fathoms off the south-west coast of Ireland
both dorsal and ventral bristles are shorter and proportionally thicker, the former being