aperture is richly ciliated, and Mr. Watson found "that when severed from the body the
anal aperture contracted at regular intervals of four or five seconds.
Habits.—This is one of the forms which aids in counteracting the effects of the borings
of Pholas and other forms, and in resisting the erosion of the sea in every climate. It is
agile in movement in its tube, to which it clings with great pertinacity, but is somewhat
sluggish when removed, lying in the vessel with the tentacles ventral, and the branchi»
generally though not always dorsal.
Arnold Watson observed in a living example that the tail at times assumed a
moniliform outline, and that the bristles posteriorly were in constant motion, apparently
assisting in the circulation of the water and the expulsion of waste matter. The long,
liook-lamellæ were always in contact with the lining of the tube as the body moved
forward or backward. The same observer (in MS.) considers that this species is that
best fitted for study from its hardihood, living always under water, whereas 8. alveolata
prefers alternations of air and water. In Scotland, however, 8. spinulosa covers
considerable areas between tide-marks, so that it follows similar habits to S.
alveolata.
Mr. Watson considers that rotation of the body on the long axis of the annelid is
produced by the bristles on the third, fourth and fifth feet, which are so arranged that a
cross-thrust can bè obtained, the small ventral fascicles being directed forward at a right
angle to the body, whilst the broad lateral fascicles of short bristles are directed backward
as if to thrust the body out of the tube.
Reproduction.—Breeds in May at Plymouth (W. G-arstang) ; September (Allen)
mature specimens in September in Ireland (Southern). Arnold Watson found the ova
collected in Wales in June of a deep pink hue* and a specimen only a quarter of an inch
long discharged about sixty. They are larger than the ova of ./S', alveolata. Dehorne1
observed that the number of the chromosomes in the spermatogenesis of this species was
eight, so that it agrees generally with what Schriener found in Tomopteris and Oplmjo-
trocha. The larvæ are abundant in the tow-nets during the summer months off the east
coast of Scotland.
Fauvel9 notices that the larvæ occurred at St. Vaast-la-Hougue in July.
The tubes are composed of coarse shell-gravel, or sand-particles more or less neatly
cemented together, and forming as a rule at the East Rocks, St. Andrews, large masses,
apparently having no very definite arrangement, though fracture reveals many tubes
running in the same direction, yet they are often sinuous. Apparently each tube is closed
posteriorly. Single tubes occur on shells and stones. The materials of which the tubes
are composed show endless variety ; fine sand-grains may form one part of the tube,
coarse shell-gravel another, and larger fragments of shells, or Balani, may be on a third
region. Internally the tube is lined by the secretion, and a fold of this sometimes
occurs at the aperture, which is slightly dilated, the margin being inclined outward so as
to make a firm hold for the paleæ. At Lochmaddy, North Uist, the tubes, composed of
sand-particles, are met with singly as long, wavy diminishing tunnels, the posterior end
being pointed. This locality was in strong contrast, for instance, with St. Andrews,
1 ‘Assoc. Française l’avancem. sc. Lille/ 1909, p. 124.
2 ‘Ann. Sc. nat. Zool./ 9e sér., t. x, p. 2Q8.
where the tubes as a rule formed masses. Amongst the tubes are many other forms
which seek shelter in their grooves or cavities, such as Syllids, Nereids, Ephesia,
Pholoe, etc.
When in its tube all the branchiae are directed forward—sloping obliquely toward
the middle line. The triangular lateral process in front of the first or thoracic region is
directed forward. The dorsal bristles follow the direction of the branchi». On the
other hand, the lateral lamellae for the hooks are directed backward and flattened to the
sides, even the cirriform terminal ones having this tendency. The crown and its pale»
form an effective operculum, and even in spirit the animal cannot be released by dragging
it from behind.
The closure of the tube at the posterior end is an important feature in connection
with the circulation of the water. When the closed end is fractured the animals fail in
health and frequently abandon the tube' (Arnold Watson).
On the French coast the tubes of this form are sometimes accompanied by those of
S. alveolata, and thus De Quatrefages confused the structure of the two species.
Varieties.—Besides normal examples preserved on oyster-shells off St. Peter Port,
Guernsey, two are peculiar in having irregular crowns. In one the dorsal fissure between
the halves is enlarged; the pointed papill» are present on the right, but are absent on the
left, with the exception of a single large one, their places being taken posteriorly by an
imperfect outer row of small flattened .pale» which cease about half way ventralward.
Little regularity is observable in the left half of the crown except that a curved row of
the second series occurs dorsally, and a fleshy bare pad occupies the position of the inner
series. All the rest are irregular, but the various types of the three series are present
amongst them. On the right the outer row is more regular, though not normal, and the
individual pale» show peculiarities, such as ending in a single blunt point, though a few
are nearly normal. In the other example the row of pointed papill» is present on the
right and on the posterior half of the left.. The outer pale» on the right are nearly but
not quite normal, the left are irregular, and the second and third series are irregular on
both sides. In both the condition appears to be due either to injury or congenital
defect.
A specimen in the British Museum is labelled Psamatotus alveolatus, Dr. Johnston.
Dalyell1 (1853) appears to refer to this species under the name of Sabella alveolaria,
and he gives an interesting account of its tube-making, reproduction, and general habits
in confinement. It showed a decided preference for sand rather than pounded brick or
glass.
Besides this form, Dr. Johnston (1865) described Sabellaria crassissima and figured
one of the pale», but so far as can be observed it is a variety of S. spinulosa,, or the author
has confused the two British species (De St. Joseph). Dr. Johnston considered Alveolaria
lumbncalis (Mus. Leach) this form.
De Quatrefages (1865) probably included this species under 8. alveolata. The figures
referred to in the synonymy pertain to 8. spinulosa. The occurrence of the two
species in company on the shores of France led the distinguished French author to
confuse them.
1 ‘Pow. Créât./ vol. ii, p. 176, pi. xxv, figs. 1—3.