been fixed the annelid by a to-and-fro motion appeared to rub the inner surface of the
tube with the region just below the palps, where it is probable glands for secreting the
lining of the tube may exist. He has studied the building organ in a young specimen
2 mm. in length (Fig. 138, p. 27), and two main apertures are present, one at each side
of the organ.
Mr. Watson also noticed in a young example the ejecta discharged from the gut
in a thread-like form, and worked forward by ciliary action and perhaps the movement
of the bristles. The annelid then protruded its anterior region, and with a sudden jerk
inward the refuse was dropped outside the tube. He also noted that where the tube
was broken posteriorly the aperture was closed by a translucent brownish secretion, so
that the respiratory and other functions could thus be efficiently carried on.
Ellis 1 (1755) gives fairly good figures of the annelid with its opercular crown, and
observes that the tubes are interesting as showing a series of saucer-shaped enlargements,
and this observation is correct, though such has not hitherto been observed in the
Scottish spécimens—it may be from their incompleteness. Ellis thought the animal made
a cover of sand at these enlargements for protection, and when alarmed retired into the
narrow part of the tube. Mr. Arnold Watson sent a fine example from the English
coast in which these enlargements occurred at the ends of the tubes throughout the
entire surface.
Guettard (1774), after Reaumur and Ellis, gives a description of this and another
speciea under the title Psavnatotus, with a brief historical account from Reaumur
onward, and shows that Linnaeus at first placed Sabellarian tubes amongst the tubiporous
corals, and that Baker erroneously located a true polyp in the tube of the annelid.
Guettard’s examples of the annelids were chiefly attached to shells. His figure is
quite recognizable. He termed it Penicilliis—Pinceau.
Pennant’s figure (1777) shows the tubes in mass, and he terms the species Sabella
radis, correcting in the subsequent edition the name to Sabella alveolata.
This is the Alveolaria arenosa of Leach in the British Museum, from Sandgate, Kent,
and termed by Dr. Johnston Sabellaria crassicornis.
Donovan (1801), in his ‘ British Shells,’ gives a bold figure of the funnel-shaped
ends of the tubes, and specially refers to it. His figure represents even a more expanded
condition than that on Plate CXXXIII, fig. 15.
Montagu (1805) noticed that the aperture of each tube is considerably expanded,
and the whole has somewhat the appearance of a honeycomb. The length of some of
the tubes was nearly 3 inches.
Cuvier terms it Amphitrite alveolata, and gives an enlarged coloured drawing of the
animal protruding from its tube, and a coloured view of the operculum—more elongated
(elliptical) than 8. spinulosa.
De Blainville, again, figures the tubes with both cylindrical and dilated ends.
Sabella alveolata was included by Milne Edwards in the 1836—49 edition of Cuvier
under the Amphitrites, along with Terebellids, Amphictenids and Chlorcemids.
1 ‘Nat. Hist, of the Corallines.’ Ellis’s figure, or one resembling it, has been copied by
various authors, such as Chenu (IIe livr., pi. ii, fig. 7).
Horst1 (1.881) investigated the development of Sabellaria (his Hermella) alveolata at
Wimereux and corroborated some of the points, such as the formation of a perivitelline
space, mentioned by De Quatrefages. He believed that more spermatozoids than one
entered the ovum, that, in contradistinction to De Quatrefages, the first plane of segmentation
occurs in the direction of the point where the polar globules appeared. He differs also
in regard to the segmentation, and found that the “ animal spheres ” surround the
vegetative part of the ovum, forming an “ amphiblastula.” When four days old the larva
has a dome-like form with a cephalic tuft of long cilia and the peritroch, and there are a
mouth and ciliated oesophagus separated by a constriction from the gut. There are four
provisional setas and two ocular patches. His figures are good, the latest (raetachete)
stage of the larva with its long spinous temporary bristles and reddish pigment being
characteristic.
Giard2 (1913) noted that Axionice fiexuosa frequently occurred at Wimereux in
masses of Sabellaria alveolata. He may refer to another form.
In the British Museum an example from Sandgate, Kent, has Sabellaria crassissima
over the old label Alveolaria arenosa, Mus. Leach. It is further interesting that the
Sabellaria saxicava, Baird, is only an ordinary example of the genus in the usual tube of
coarse sand which, has subsequently been coated with Lithothamnion. It came from
Vancouver Island. So far as known there is no. borer in the family.
Hornell (1891) mentions that a mite is frequently found parasitic on this species in
the Liverpool district (Hilbre Island).
Family XXVII.—A mphictbnidæ, Malmgren, 1866.
Amphitrite, O. F. Müller ; Terebellum, Denys dé Montfort ; Pectinaria, Lamarck ;
Amphictenea, Savigny, Grube.
Cephalic region obliquely truncate or semicircular, with two rows of powerful golden
bristles (paleolæ) nine to seventeen in number which exactly fit the aperture of the tube,
and which are compressed, tapered and arranged in contiguous series in two rows
attached to the buccal (second) segment. Above the paleolæ is a firm region with a
smooth or fimbriated border, whilst beneath them is the membranous fan-shaped veil
with cirri on the margin (rarely entire). To the base of this on the dorsal arch of the
mouth a group of contractile grooved tentacles is affixed on each side. Tentacular cirri
two, the anterior springing from the side of the head, the second from the first segment.
Body of comparatively few segments, and of several regions differently constituted, viz., a
buccal, an anterior or thoracic region, large and devoid of hooks, a posterior (abdominal)
region with prominent lamellæ for hooks, and lastly a short posterior appendicular
or caudal region of about five to six segments (scapha), usually bent at an angle,
excavated above and convex ventrally, the margin crenulate and with a valvular
flap above the anus. Intestine longer than the body. Coelom with one anterior
1 ‘ Yersl. en Meded. afd. Naturk. Amsterd.,’ 2d R D° xvi, pp. 207—214, and plate.
2 OEuvres Div., p. 57.