membrane. This feature is common in the Terebellids and others. Meyer, like Cunningham
and Ramage, again suggests that the peristomial lobes may represent the dorsal
division of the foot of the first segment, and Allen says that in Poecilochaetus the feet of
the first segment are much enlarged and directed forward. Meyer further thinks that
the Hermellidm are closely related to the Spionidm.
The body behind the foregoing is divided into three regions, viz. the first, devoid of
hooks, and with four bristled segments, the second of about forty segments (Allen) with
bristles, hooks and gills, and lastly, the caudal tube with its crenate and frilled extremity.
The dorsal surface anteriorly is somewhat flattened, or at first grooved, then rounded
posteriorly, whilst ventrally it—is rounded in the first region and grooved in the second.
The first region is firm and rounded, then a slight dilatation occurs at the commencement
of the second, and little tapering ensues till near the tail, where, after gently diminishing,
it tapers somewhat abruptly to the caudal tube. The general colour of the body is buff,
with dark chocolate-brown markings in the region of the thorax and peristomium. The
branchiae are dark olive-green, and the smooth caudal portion is also dark green (Allen).
The first segment presents dorsally a pair of branchiae somewhat less than the second,
then a free lamella divided into two, viz., a truncated flap with a conical median papilla,
followed by another with two papillae, broadly conical, then the setigerous papilla, and
lastly the ventral cirrus, which is conical on one side and bifid on the other. The
bristles differ from the succeeding in being longer, simple, finely tapered and smooth
(Plate CXXIII, fig. 1 c). They therefore correspond in structure with the enclosed
bristles observed in Sabellaria spinulosa, and are usually, in the preparations, directed
forward and inward toward the mouth.
The other bristles of the region, viz. on segments 2—5, consist of flattened spatulate
forms with translucent tips—split like a brush and directed dorsally forward and slightly
inward. Each (Plate CXXIII, figs. 1 d and 1 d1) has a fillet or rim at the base, then the
striated shaft slightly dilates all the way upward to the flattened faintly striated blade,
which has a brush-like tip. When these bristles pierce the surface, the tip is pointed and
entire, but it subsequently becomes frayed. In each tuft between these are slender
tapering bristles (Plate CXXIII, fig. 1 e) with hair-like tips which are minutely spiked so
that foreign structures readily adhere. These are shorter than the spatulate forms. The
dorsal bristles of this region are powerful organs borne by four large flattened lamellae,
which increase from the first to the last, and have a direction obliquely outward and
backward. Their structure is uniform throughout, each tuft having large flattened
spatulate bristles' arising from a bristle-sac or cell, the striated shaft dilating gently from
the base to the oar-like tip where a more decided enlargement occurs, and then slightly
narrowing distally.
The next region of the body is characterised by the great development of the
branchiae, and by the presence of the forty lateral lamellae for the hooks. A typical
foot consists of the branchial process dorsally, the thick lamellae with the hooks on the free
ridge, which has a rounded end dorsally, but ventrally the obliquity of the edge leaves a
bluntly conical process followed by an acutely conical cirrus or flap behind the ventral
bristles, and lastly, the edge of the latter is connected with the body by a free frill with a
notch in its margin. Such is the condition in one of the large feet in front, but by-and-by
the bristles become more prominent and longer, the uncinigerous flap projects more
laterally than ventrally, and the region of the conical cirrus becomes a flattened ridge with
a small papilla ventrally—behind the prominent setigerous process. The ventral bristles
are in front directed obliquely inward and forward, but as they become longer and more
slender posteriorly they have a tendency to slope outward and forward, and lastly, in front
of the caudal process, the long silky hairs are directed backward, as, indeed, Dr. Allen s
figure indicates.
In structure the ventral bristles (Plate- CXIII, fig. 1 &). have long smooth shafts with
whorls of spikes on the tip, which is extremely attenuate. Moreover, in glancing at the
fascicles it is apparent that two series of bristles are present, viz., the stronger kind just
described, and a less robust series which are finely tapered and quite smooth. All have
tapered bases with the fillet at the tip, and the shafts are translucent. The same structure
prevails in those immediately in front of the caudal process, the whorls of spikes being
very distinct, but the smooth bristles have now attained pre-eminence, and their finely
tapered extremities stretch far beyond those with the whorls of spikes.
The branchiae are twenty-one in number, including the rudimentary forms posteriorly,
and are of a deep brown colour. The first is smaller than the second and has only a single
frill. The second is flattened and has a double frill—that is, one along each edge. Those
folio wing have a single frili situated along the anterior and inner border. They reach their
maximum size about the seventh or eighth segment of the third (abdominal) region, and
thereafter diminish in bulk, the frill disappearing in three or four of the more slender
terminal branchiae.
The hooks, which form dense rows on the edges of the lamellas, have an elongated
form (PI. CXXIII, fig. If), the posterior outline being almost straight, a very slight
convexity occurring in the middle. In the anterior hooks the crown is rounded, the outline
being broken only by the slight notch for the attachment of the tendon. As a rule
six recurved teeth are present, though a minute additional one is often seen at the crown.
The prow is somewhat narrower than the crown and is also more or less rounded; minute
incurvations for the attachment of the two tendons, however, occur. On the other hand the
posterior hooks (Plate CXXIII, fig. 1 g) have a distinctly concave posterior outline and a
more convex anterior edge usually with eight recurved teeth, the crown and base being
similar to those in front.
The caudal appendix shows four or five transverse ridges and papillas on each side at
its commencement ventrally, as if such indicated a continuation of segments. On the
dorsal surface rings only occur (Plate CXVIII, fig. 1).
The tubes (Plate CXVIII, fig. 1 d) are built of two layers, an internal layer of
comparatively small pieces of shell or thin, flat stones, arranged with considerable regularity
and forming a smooth internal surface, and an external layer of large pieces of
gravel and shell forming a strong but rugged and irregular outer covering (Allen).
Arnold Watson has found that the animals are social with gregarious tubes, “ which are
as smooth externally as can be expected since they are composed chiefly of small shells
or other fragments attached by the flat surface, with here and there a larger shell at long
intervals. Most of the pieces are evidently from the middle of the tube, both ends being
absent, but the outer ends of the tubes are only half as thick as these, the diameter is