make a series of circular bauds, as in S. penicillus and other forms, thus conferring great
beauty on the expanded organs. In some cases when mounted the reddish-brown
pigment is in isolated masses at intervals along the filament and patches occur on the
terminal process. There are about 11 filaments on each side springing from the central
region of the cephalic plate, a basal fissure, most distinct ventrally, occurring dorsally
and ventrally. They are connected only at the base and free throughout the rest of
their extent, and are long tapering organs with proportionally short pinnge, which as
they reach the tip gradually diminish in length, and end in a series of short papillae
at the base of the terminal strap-shaped tapering process. The chordoid skeleton is
continued along the centre of the flattened tip, and into each pinna. In young forms
the pinnae are short, but the flattened terminal strap is well developed.
The body is comparatively small, elongated, and distinctly segmented throughout—-a
feature characteristic of the species. Segments fifty-six, but the tail in the majority of the
examples was in process of reproduction, so that the actual number of segments must exceed
the figure mentioned. The body is widest in front and gradually tapers behind the middle
to the posterior end, where the rounded anus is terminal. The dorsal surface is more or
less rounded, the ventral flattened and marked by the scutes from end to end. A slight
depression occurs in the mid-dorsal line anteriorly, and continuing to the right behind the
sixth bristle tuft it crosses the seventh segment obliquely to the middle line at its posterior
border, whence it passes to the tip of the tail, cutting the ventral scutes into two in each
segment. Six bristled segments are present in the anterior region and five uncinigerous
rows, but occasionally only five and four occur respectively. Other variations, apparently
arising from lost parts in process of reproduction, show the ventral furrow running to
the front, or a diminished number of anterior ventral scutes. Moreover, the two anterior
scutes may be split by a furrow quite independently of the main-ventral furrow. The
first setigerous process is situated behind the collar, and is inconspicuous. It has a
small tuft of simple bristles with acutely tapered tips and narrow wings as in the dorsal
group of the anterior region. The bristles of the succeeding segments of the anterior
region (five in number) have dorsally translucent bristles with straight shafts and finely
tapered tips and narrow wings, the upper, having longer and more delicate tips, and
ventrally narrow, spatulate forms (Plate CXXVIII, fig. 1 a), the outline of the wings
being more or less a long ellipse, the tapering shaft being continued as a fine process
distaily. Moreover, those with broader tips form a shorter row than those with more
elongated tips. The outline of the tip of the latter bristles thus essentially differs from
that in Potamilla reniformis and also from those of P. Torelli. In the posterior region
the bristles form a tulip-like fascicle with a knee or curvature on each bristle toward
the end of the shaft, the convexity with the wings being external. Those with the
longest and most delicate tips (Plate CXXVIII, fig. 1) are dorsal, those with slightly
broader wings (fig. 1') are ventral, and the former are most conspicuous near the tip of the
tail. In the anterior region five uncinigerous rows lie to the ventral edge of the setigerous
processes, their inner ends impinging on the scutes opposite them. The first commences
opposite the second bristle-tuft, and all are longer than those of the posterior region. The
hooks (Plate CXXVIII, fig. 1 b) are in a single row with a main fang and a series of serrations
above it, a neck of moderate length, with strise where it enlarges into the boldly
convex prow, and an oblique, tapered base (corresponding to the shaft). Moreover, a series
of short, modified bristles occur with them, the tips being short, bent at an angle and with
broad wings, the whole resembling a beak. The curved shafts dilate from the base to the
neck, where a slight constriction occurs; then it bends forward and tapers to the short
tip. In some views slight grooves appear on the enlarged basal part of the tip, so that
they at first sight resemble the long hooks of Terebellides and other forms. The posterior
hooks (Plate CXXVIII, fig. 1 c) are smaller, their necks longer, and the bases more
oblique.
Tube.—Borne are in tubes of tough secretion with a few fine sand-grains attached,
after the manner of the Canadian examples of P. Torelli.
Amongst the masses of the foregoing Sabella B.G. from Berehaven are a few
characterised by the striking madder-brown pigment-spots on the branchige, and without
the general arrangement of the pigment characteristic of the former Sabellid B.C.
Yet in the disposition of the cephalic collar the two forms appear to be identical. It is
true some of them show seven anterior segments with bristles, but others have the normal
number, and some which apparently have lost the cephalic plate and other parts have
fewer. Injury or abnormality also would explain the occurrence of the median ventral
furrow from the first scute backward. The anterior hooks and their accompanying
bristles and the posterior hooks are identical.
Genus CLXIII.—Laonome, Malmgren, 1865.
Cephalic region with the collar slightly developed, and a wide dorsal fissure which
increases from behind forward, the margins being slightly reflexed, whilst the edges of
the ventral fissure are carried a little further forward and the one overlapping the other.
Branchiae forming a semicircle on each side, not elongated; filaments with slender
tapering free extremities, and bearing ocular spots. Tentacles comparatively short, broad
at the base, tapered to a blunt point. Body elongated, little tapered anteriorly, more so
posteriorly, rounded, with the anus terminal. Ventral scutes broad in front, forming a
narrow belt posteriorly divided by a median groove. Dorsal groove turns to the left and
joins it, . Setigerous lobes from the second segment, bearing long, tapering winged
bristles and paddle-shaped forms, posteriorly bristles with broad wings and finely tapered
tips. Hooks commence at the second segment, are avicular throughout, but the basal
region posteriorly shows only a rudiment in the anterior bristles, and is absent in the
posterior. Tube of secretion and mud. This genus extends to the Antarctic Seas.
1. Laonome Kroyeri, Malmgren1865. Plate CXXIX, figs. 3—Be—branchia, bristles
and hooks.
Specific Characters.—Cephalic region with a short collar widely split dorsally, the
sides of the ventral hiatus overlapping in spirit. Branchial (fourteen to sixteen) of
moderate length, the chordoid axis with narrow segments toward the base; plunge of
moderate length, ;the tips delicately filiform. Tentacles short, bluntly tapered. Body
narrow and long, somewhat rounded; ventral scutes broad in front, continued posteriorly