the additional item of the nephridia, however interesting these may be as corroborative
distinctions.
In his second division, in which the branchiæ are absent, all the nephridia are free,
though the anterior may vary in size from the posterior. Here are Leoena, Proclea,
Laphania, Lanassa, Pliisidia and Spinosphæra. The first four and probably all form
a natural series.
In the third group, which has branchiæ, nothing is entered about nephridia, but the
hook-rows are single or absent and the branchiæ are filamentary. In this division are
Thelepus, Streblosoma and Pamtlielepus.
The fourth group is devoid of branchiæ and the nephridial characters are not
entered. It contains Amoea, Polycirrus, Lysilla and Hauchiella, the last (the Poly cirrus
trUmllata of the author) having neither bristles nor hooks.
The Terebellidæ have various ectoparasites, generally Protozoan. Thus Gothunna
was met with by Schmarda on Terebella macrobranchia ; Rhabdostyla sertularium on the
branchiæ and feet of the Amphitritea and on Lepræa lapidaria from Naples by
De St. Joseph ; and Rhabdostyla arenicoloe, Fabre-Domergue, has also occurred, and on
the tentacles of Nicolea venustula De St. Joseph records Ophryodendro-n annulabrum.
Crustacean parasites are rare in the Amphitritea, but Sars mentions Tei'ebellicola
reptans, a female of which was fixed to a Terebellid1 and Levinsen Grypsidomus
Terebellæ, which with its egg-sacs lived in the intestine of Amphitrite cirrata.
Busch8 (1851) describes and figures a pelagic Terebellid larva in its tube, similar
to that formerly recorded by Milne Edwards, and subsequently^ by Giard, E. Nordenskiôld
and others.
Several stages of Terebella Meckelii are given .by Claparède and Mecznikow (1868).
They show the segmenting egg, the trochophore, the larva of two segments, and
lastly one of six bristled segments in the pelagic stage (so-called Wartelia) in its
transparent tube, with its complete alimentary canal, viz., proboscis, oesophagus,
stomach, intestine and vent, on each side of which is a papilla. A pair of segmental
organs occur opposite the first two bristle-tufts. They thus supplement the previous
stages described in Terebella conchilega by Claparède (1868).
Willemoes-Suhm8 (1871) found the larva of Nicolea in April in Kiel Bay, the
early forms being pear-shaped and ciliated; then they become more elongated, being
cylindrical and tapered at each end. The next stage has a conical snout and four
eyes, with three bristled segments and two papillæ posteriorly. He describes the ova
of T&rebellides stroemi as attached to sea-grass by a stalk, and gives an account of the
early stages (trochophores) with two reddish eyes and an otocyst.
Hacker (1896) thought the Terebellids and Arenicolidæ had not pelagic larvæ,
for they only rotated in their galleries. Terebellides stroemi, however, has pelagic young
(Willemoes-Suhm). The same author4 (1898) mentions a Terebellid larva from the
Sargasso Sea which had formed its tube of Radiolarian skeletons. As it was included
1 ‘ Christ. Vidensk.-selsk. Forhandl./ 1861, p. 46 (sep. copy).
2 ‘ Beobach. Anat. u. Entwickel. Wirb. Seeth./ p. 73, Taf. xi, fig. 7.
8 ‘ Zeitsch. f. w. Zool./ Bd. xxi, p. 388, Taf. xxxiii.
4 ‘ Plankton Exped. Polych., etc., Larvæ/ p. 31, Taf. iv, fig. 39.
in the “ Drift-Larvæ ” it was probably pelagic. Those captured in British waters have
hitherto had transparent tubes of secretion.
Erik Nordenskiôld1 (1901) gives a careful account, with a plate, of the structuré
of a larval Terebellid ( Wartelia) which he found at St. Andrews.
Some remarks on fossil Terebellids comparatively recently (1911) made by
Dr. Bather3 are of special interest, since certain tubes originally described by W. Davies
are partly composed of the bones and scales of various species of fishes—a feature
apparently unknown in living forms, though the composition of the tubes is sufficiently
varied. The slender fin-rays are arranged in the long axis of the tubes, just as the
linear leaves of the pines are in the Japanese forms of the “ Challenger ” and in those
from the cretaceous beds of Bohemia. Tubes composed entirely of secretion occur both
in these fossil types and now. Whilst tubes of the same species are generally speaking
similar, it may happen that a widely distributed species removed from its ordinary
surroundings in sand to a muddy bottom in deep water is compelled to fashion its tube
of neatly arranged sponge-spicules placed transversely.
^ Terebellids abound on sandy shores, especially beyond low water, though many
fine species occur between tide-marks and in fissures of rocks. Others inhabit deep
water, even to great depths, viz., 2750 fathoms. They are strictly tubicolar, though
some, as Nicolea venustula, when free were found by Michaelsen to swim freely, and
others do the same. In size they range from 40 cm. downward, and their colours are
often both varied and bright, the rich red branchiæ, the roseate tentacles and the
speckled body of certain forms being noteworthy.
Young Terebellids are abundant in the pelagic condition, especially in the bottom
tow-nets from May to September, in their transparent tubes shaped somewhat like a
post-horn, and they are accompanied during the warmer months by young examples
of Glione. A post-larval Terebellid, Amphitrite præcox, of De St. Joseph, possesses long
bristles like an epitokous form, and develops ova.
Their food consists of the forms in their immediate neighbourhood, such as
Diatoms, Foraminifera, Radiolarians, spicules of sponges, and fragments of Polyzoa,
molluAscss manedn thioynderdo,i desx. ternal crustacean parasites (e. g. Terebellicola) are rarely present,
but Distomes occur anteriorly in the gut (De St. Joseph), a Nematode {Lyorhynchus,
Rud.) in Loimiamedusa, and another and a Tetrarhynch in Poly cirrus, whilst Protozoan
parasites, such as Gothurnia, Rhabdostyla and Ophryodendron are more common.
Terebellids are by no means sluggish animals. When freed from their tubes they
swim actively with a quick, wriggling movement, the tentacles being m front; the jerks
are rapid and vigorous, and they make considerable progress.
The tubes of the Terebellids comprise many and varied structures, from the fringed
anterior processes of Lanice conchilega to the remarkable spinose tube of the “ Challenger ”
species, or the more delicately hirsute tube of the British Terebella B (Plate CXIX, fig. 7).
The compact spiral tube of Caullery’s Streblosoma longiremis is another curious form,
1 ‘ Ofversigt Finsk. Vet.-Soc. Forhandl./ B. xliii.
* " Upper Cretaceous Terebelloids from England,” f Geol. Mag./ dec. v, vol. viii, p. 481/pl. xxiv.