SiiiiPULiD^. ANNELIDA. Sabellakiiu^. 299 
are neither antennae, ej'es, proboscis, nor jaws visible 
on the crown, or on a lobe above the mouth, or on 
each side near the mouth. On the anterior segment 
of the body we see in most of the species a series of 
filiform extensile tentacles, and on the first two or three 
segments the branchiae are placed. These organs are 
few in number, are large, much branched, plumose, or 
pectinated; and are arranged along the sides, rarely on 
the middle of the back of these anterior segments : 
sometimes the}' are wanting altogether. The feet are 
distinct, but not projecting or fitted for enabling the 
animal to walk, as in the preceding order. They are 
not uniform in structure, but present a different appear- 
ance in different parts of the body. They are biramous, 
enlarged transversely, and armed with the ordinary 
setaceous bristles, as well as with hooked bristles or 
uncini, which serve the animal for moving up and 
down in its tube. The mouth is terminal and placed 
transversely. Some of these Annelides form a homo- 
geneous calcareous tube, which is generally attached to 
a stone, rock, or shell, &c. Others construct tubes by 
agglutinating grains of sand, fragments of shells, and 
particles of mud, which they join by means of mem- 
brane. A third set, again, inhabit tubes which are 
entirely membranous or horny. 
Family I.-SERPULID^. 
The animals belonging to this family have an elon- 
gated, worm-shaped body, divided into short segments 
and distinguishable into thoracic and abdominal por- 
tions. The head is amalgamated with the following 
segments, and not noticeable in the adult. The first 
segment is encircled with a collar, which is said to be 
the part of the body that secretes the shelly tube. It 
is also furnished with a tuft of bristles on each side. 
The feet are composed of two branches. In the thoracic 
portion of the body the dorsal branch is armed with 
setaceous bristles, while the ventral is furnished with 
hooked ones. In the abdominal portion of the body 
(which is the longer) it is the ventral branch that is 
armed with the setaceous, and the dorsal with the hooked 
bristles. The branchiae are attached to the vertex or 
first segment, consist of two divisions, and resemble 
a fine plume in shape of a fan, and are, in general, 
adorned with the jnost lively colours. Each of these 
divisions consists of a pedicle, the upper edge of which 
is furnished with a great number of filaments placed in 
a line, like the teeth of a comb, and each in their turn 
provided with a double row of movable barbules. 
Though these branchiae serve the purpose of respiratory 
organs, it would appear, says Audouin, that it is not 
the only use to which they are applied; for Bose has 
observed that these animals live on small worms, which 
they attract to their mouths by the whirlpool caused by 
the rapid motion of these organs in the water. — Ser- 
pula cortortuplicata (fig. 205) will illustrate the family. 
Family II. — TEREBELLID.®. 
In general form the animals of this family resemble 
very much the preceding, being vermiform and cylin- 
drical, without distinct head, and divided into thoracic 
and abdominal portions. The feet on the thoracic 
portion are similar to those of SerpuUdee^ but on the 
abdominal portion the dorsal bristles, or both dorsal 
and ventral, are frequently wanting. The branchias 
are pectinated or much branched, rarely filiform, and 
placed laterally. These animals inhabit membranous 
Fig. 205. 
tubes, which are coated with particles of sand, gravel, 
or broken shells agglutinated together, and open at 
both extremities. 
Family III.— SABELLARIID^. 
In this family the body of the animal is composed 
of few segments, and is divided into two distinct por- 
tions. The anterior portion has the segments provided 
with setigerous and uncinated feet ; the posterior is 
narrow, without segments, and without feet, more like 
a caudal appendage. The first segment is large and 
truncate, disc-shaped, and having an operculum com- 
posed of several rows of flattish bristles. The mouth 
is placed in the centre of this disc, and encircled with 
a somewhat extensile lip. The feet are in two series ; 
the upper prominent, armed on some of the anterior 
segments with flat, or sometimes hooked bristles, and 
on the following segments with small fascicles of capil- 
lary bristles. The branchiae are in pairs on all the 
segments. 
