after preservation inch, and it had about sixty-six segments. The first two
bristle-tufts are somewhat short, the third to the sixth are long, and these corresponded
to the first region of the body ; consequently only five pairs of dorsal hook-rows are
present. The seventh pair of bristle-tufts is slender and small, so that the outline is
narrowed, the adjoining tufts being longer. Toward the tip of the tail elongated, slender
simple bristles occur as in the adult. The bristles correspond in arrangement and
structure with those of the adult. The anterior hooks differ in having a shorter
posterior basal process, but they are accompanied by the same paddle-shaped bristles.
The anal segment is bilobed, and has a peculiar series of dark pigment-specks.
Four pairs of setigerous processes bearing short bristles occur behind the last hooks,
which are small and only three in number. The bristles increase in length at the
sixth from the tip. The opaque glandular tissue splits at the termination of the
rows of dorsal hooks at the second ring from the latter, since the first has a bar
obliquely bevelled at the lower edge. The splitting continues to the tip of the tail and
gives a regular arrangement to the parts. Both anteriorly and posteriorly the bristles
commence before the hooks. Four pairs of bristles occur before hooks appear,
the first hooks being between the fourth and fifth bristle-tufts, and their bases
are undeveloped. The first five pairs of bristles are short, but the sixth are decidedly
longer.
Reproduction.—Lo Bianco (1909) found that at Naples the rose-coloured ova were
deposited in April. At St. Andrews ova occurred in the coelom in October.
Parasites.—M. Sars found a parasitic Copepod on this form, viz. Sabelliphilus elon-
gatus. The body is elongated, somewhat rounded, attenuated posteriorly, and has ten
segments. In the female the head is fused with the first thoracic segment, but in the
male it is separate. Rostrum bifurcate. First pair of antennæ with seven articulations,
the first two in the female much dilated, in the male less dilated. A second pair of
antennæ quadriarticulate, the terminal joint with three hooks and the penultimate with
one hook. Maxillipedes triarticulate, terminal joint with a hook. First four limbs
triarticulate, fifth rudimentary, simple, uniarticulate. Ovigerous sacs elongate,
subcylindrical.. The same parasite occurred in examples from St. Andrews and the
West Coast of Ireland, and in both cases attached to the left edge of the branchiæ at
the dorsal fissure.
Habits.—S. penicillus is fond of a muddy bottom at some depth. When sickly it
leaves its tube, apparently for better aeration. It is most active at night, and is exceedingly
shy and sensitive. The posterior end, like the anterior, can be regenerated. Thus in
a large example (Plate CXX, fig. 5) the new segments form a conical appendix with a
streaked purplish spot of pigment near the tip.
The tube may reach the length of 2 feet, and is fixed to stones on the bottom. The
elasticity of the distal end closes the aperture, the rest of the tube being composed of
secretion and mud, and so smoothly rounded as to resemble a tube of caoutchouc (Dalyell)
of considerable firmness, and some are nearly f- inch in diameter. Many are coated
with patches of, or entirely sheathed in, Alcyonium digitatwn, so that the tube must stand
more or less erect, and have free aération. In connection with the muddy surroundings
from which the animal forms its tube, further light is thrown on the azoic-mud theory of
the late distinguished Dr. W. B. Carpenter. As formerly indicated1 this theory would not
stand criticism. The lining of the tube is tough and well fitted for strengthening it.
Orton2 found that this species formed a tube 12*6 cm. long in less than thirty-one weeks,
and at this age contained well-developed, but not quite ripe ova.
Ellis (1755) terms this form “ Turkey feather,” though parts of the description do
not apply to the plate (33). He figures both tubes and animals in and out of the tubes.
He further cites it as “ Fungus auricularis.”
It is probable that the Serpula penicillus of Linnaeus (1758) refers to this species.
Pallas8 (1766) gives a fairly good figure of this form under the title of Serpula
penicillus in a vessel of sea-water. Moreover, his acquaintance with the literature of the
subject is evident by his references to Rondeletius, Ellis and Baster.
In this and in many other instances 0. F. Muller’s (1799) figures of the animals are
in advance of Delle Chiaje’s in minute accuracy and general pose.
Dalyell (1853) records a series of interesting observations on the living animal in
confinement in regard to the branchiae, the tube-building organs, and their action with
mud as well as regeneration of lost parts. He expresses wonder at the faculty by which
the annelid communicates its purpose to one, ten or one hundred of its infinite parts whilst
all the rest remain inactive. He secured young specimens with few branchiae (six) and
watched their increase and the enlargement of the tube, as well as the attachment of the
end of the latter to glass or other bodies.
Pruvot (1885) demonstrates the massive condition of the great nerve-trunks as they
leave the cephalic ganglia and the large size of the anterior commissures immediately
behind the ganglion (Plate XV, figs. 12 and 13). The great trunks have neural canals.
He notes and figures the chlorogogenous tissue around the ventral blood-vessel between
the ganglia. He figures four cephalic ganglia—’two small anterior median sending twigs
to the tentacles (his antennas) and two large ovoid lateral ganglia.
De St. Joseph (1894) gives an account of the variations in the number of the thoracic
segments and the “ sillon copragogue” (ventral groove), and he concludes that the
differences are to be attributed only to the size of the animal or its age. He enters into
a detailed account of its structure.
Cunningham4 (1888) could find no connection between the neural canals and the
cephalic ganglia. The canals reached the oesophageal commissure, and he found a single
transverse connection between the canals in the first commissure, but no more. He
noticed the coagulable substance (formerly described by the author)5 in these canals.
Hornell (1891) describes a variety from Hillbre Island with unequal tufts of branchiae,
viz., sixty-one filaments on one side and thirty on the other, and as the form is a large
one, the branchial fan being about 4 inches in diameter, the condition is conspicuous,
and he imagines such may be mistaken for Spirographis.
1 ‘ Ann. Nat. Hist.,5 January, 1872.
2 ‘ Journ. M. B. A.,5 vol. x, p. 316, 1914.
8 ‘ Misc. Zool.,5 pi. x, fig. 1.
* ‘ Quart.. Journ. Micr. Sc.,5 vol. xxviii, p. 271.
6 ‘Proc. Roy. Soc. Edin.5 1876—77, p. 380.