segmental organs of the ordinary type with ventral nephridiopores. Neural canals largely
developed. Neither thoracic membrane nor operculum.
Tube cylindrical, of mucine, leathery, or membranous, coated with dark mud, rarely
with sand or other material.
The general structure of this and several of the succeeding genera has been given in
the | Annals of Natural History ’ lately,1 so that it will only be briefly alluded to tinder the
species dealt with.
The term 44 Sabella ” was employed by Linnaeus in the tenth edition of the 4 Systema
Naturae ’ to designate a form similar to the Nereides with a tube of grains of sand, and
two thick tentacula behind the head.
Cuvier noted that the members of the group rarely possessed a calcareous tube, whilst
they had the same fan-like gills as the Serpulae, and in many the same thoracic
membrane.
The Sabellids were ranged under his comprehensive group 44 Annelides Serpulees ” by
Savigny (1820)—along with Amphictenids, Arenicolids and other forms. The special
genus Sabella (Genus XXI) was, however, described with considerable minuteness and
oare. He made three tribes, viz. (1) Sabellse Astartse, (2) S. Simplices and (8) S. Spiro-
graphes.
The circulation of the Sabellids was stated by Milne Edwards2 (1888) to be akin to
that of Nephthys and the Nereids. A dorsal and a ventral trunk are present, whilst the
inner aspect of the integument is supplied with a multitude of vascular filaments for the
secretory organs, and the bases of the feet present also a capillary rete which probably
aids in respiration, but the main respiratory organs are the cephalic fans in front.
The elder Sars did much to place the genera of this group on a proper footing by
giving carefully revised characters.
It is difficult to distinguish the Glymeneis stigmosa of H. Rathke,8 in his 44 Fauna
Norwegens ” (1843). It is apparently a Sabellid, and at first sight might pass for Ghone
infundibuliformis without branchiae, but the author was familiar with that species, and
would not have omitted reference to the elongated anterior hooks. It is, at any rate, a
Sabellid.
According to De Quatrefages (1850), the cephalic ganglia of Sabella flabellata form
two pairs connected by a large commissure. Branches from these go to the branchiae
and to the eyes. The oesophageal connectives are extremely short. The visceral system
seems to arise from the ganglia as a small twig on each side and furnished with two
ganglia. The ventral cords are separate throughout, though nearer each other posteriorly,
and the first ganglion is close to the cephalic ganglia, the others following in each segment
and on each cord. Fine connecting trunks occur between each ganglion, whilst
branches from the latter pass to the muscles and other organs. He mentions that in
the branchiae of the Sabellidae and Serpulidae are venous and arterial twigs which mingle
in a system of vessels, the walls of which cannot be distinguished from the surrounding
tissues, and in which respiration is carried on through the thin covering tissues and
1 ‘ Ann. Nat. Hist./ ser. 8, vol. xvii, 1916, p. 1.
8 Op. oit., p. 212.
3 4 Nova Acta Cur./ Bd. xx, p. 228, Tab. ix, figs. 10—14.
their cilia.1 He describes what he terms a cartilaginous skeleton in these branchiae,
composed of cells, with a tough fibrous investment like a periosteum. He refers to the
chondroid tissue of the organs.
This family was united with the Eriograpliididæ and the Serpulidæ, under which
latter title the whole were ranged by De Quatrefages (1865), but it is difficult to see
what was gained by this method, which, if anything, increased the complexity of the
subject. It is true it led to certain interesting homologies of the organs of the two
families, such as that of the tentacles of thè Sabellidae with the opercula of the
Serpulidæ. In his arrangement of the large family thus constituted De Quatrefages
employed the operculum, the regions of the body, the branchiæ, the tentacles, the feet and
the tubes in separating the genera, of which he made twenty-one. Under his first tribe,
the Serpulea sabellea, were ranged the Sabellids proper, Oria, Fabricia, Amphiglena, and
Protula, whilst in the second division, the Serpulea heterosabellea, were Anamæbæa,
Amphicorina and Myxicola. He distinguished these from the former by the supposed
indistinct separation between the thoracic and abdominal regions—a misapprehension
corrected by Claparède.
Following De Quatrefages Dr. Johnston (1865) included the Sabellidæ under the
Serpulidæ. Grube (1878), like various previous authors, placed the Sabellidæ along with
the Serpulidæ in his Family Serpulacea, Blainville. This author in 1838 showed that
the vessel to the branchial filaments was single.
Claparède (1868), following Burmeister and De Quatrefages, included the Sabellidæ
under the Serpulidæ as the first tribe of that group, and distinguished from the other
tribe by the fact that they have no thoracic membrane whereas the Serpulids have.
Moreover, the Sabellids are characterised by the presence of a ciliated median ventral
groove, which, passing between the right feet at the posterior part of the thorax, becomes
dorsal in that region. This 44 sillon copragogue ” of the Swiss author carries fæcal
matter to the front, and discharges it from the tube without contact with the mouth.
In those species in which the groove is ventral throughout it becomes less and less deep
anteriorly and disappears in front, so that when the animal projects its anterior region
from its tube at the usual angle the fæcal matter is dropped at a distance from the
mouth. He corroborated Grube’s observation that the blood-vessel to each branchial
filament was single, and that the skeletogenous support was independent of the
perivisceral prolongation.
Langerhans . (1880) groups the Sabellids under his Serpulacea, but readily
distinguishes them from the Serpulids by the absence of the thoracic membrane. He
arranges the genera of the Sabellidæ thus :
I. Tori on the thorax with two rows of bristles.
a . With a collar.
a. Branchiæ spiral . . . . . . . . . Spirographis.
b. Branchiæ simple.
a. Sub-terminal branchial eyes. .....................................Branchiomma.
(3. No sub-terminal eyes.
1 Grube and Claparède, on the other hand, pointed out that in the Sabellids the trunk to the
filament was single.