(a) Bristles with a simple point. Hooks having a rounded base which
is prolonged in the anterior segments or throughout ; three to five
rows of denticles on the vertex.
Rows of hooks alternate, or double; two to three pairs of
branchiæ—Pista, Mgrn.
Two pairs of subulate branchiæ—Eupista, McIntosh.
(ib) Hooks clustered or thick-set with moderately long base, a ligament
for fixing, three to five teeth on the vertex and from three to twelve
denticles (teeth) in all. Rows of hooks alternating in a certain
number of segments. One pair of branchiæ with few branches—
8done, Mgrn.
(c) Two teeth and two transverse rows on vertex- of-hook ; two pairs
of ramose branchiæ—Nicolea, Mgrn.
(d) Hooks with elevated crest, and base of moderate length. Two
teeth and two transverse rows of two to three denticles. Two
rows of hooks ; three pairs of finely branched branchiæ ; seventeen
setigerous segments—Lanice, Mgrn.
(e) Hooks not clustered, with a long base ; two teeth on the vertex ;
two transverse rows of one to three denticles. Double row
of hooks facing each other, rarely simple and alternate ; three
pairs of arborescent branchiæ; seventeen setigerous segments—
PoVymnia, Mgrn.
2. Bristles commencing on the second or third segment, with simple points.
Hooks with a long base and a button ; two teeth on vertex, two transverse
rows of denticles or more. Hooks in a single row, retrogressive.
(а ) Bristles beginning on the third segment; two or three pairs of
cirriform branchiæ—Thelepus, Leuckart.
(б ) Bristles commencing on the third segment ; three pairs of cirriform
branchiæ—Grymoea, Mgrn.
Two or three pairs of subulate branchiæ as in the Ampharetidæ—EutKe-
lepus, McIntosh.
II. Hooks pectiniform, without transverse rows of denticles on the vertex ; four to six
teeth. Double row of hooks in certain segments. Three pairs of arborescent
branchiæ ; seventeen bristled segments—Loimia, Mgrn.
This classification does not seem to facilitate rapid work, and the variations in the
rows of denticles on the crest of the anterior and posterior hooks are considerable. The
form of the hook would appear to be of greater moment than the number of these teeth.
Other authors have increased our knowledge of this group, such as Ehlers, Gravier,
Fauvel and Wirén.
The presence of otocysts in the Terebellidæ was first pointed out by Claparède in the
larval Lanice conchilega, and in the young of another Terebellid by Agassiz, whilst Giard
and Nordenskiôld worked at the same form as the first mentioned, considering it a special
form which Giard termed Wartelia. Meyer and Andrews also added to the knowledge
of the subject, whilst Fauvel (1909) carefully investigated it by serial sections,
and found only two Terebellids, viz., Lanice conchilega and Loimia medusa, possessing
otocysts.
An account of the circulatory and digestive systems in several species was given by
Wirén (1885), accompanied by excellent figures.
Goodrich1 (1900) observes that in the Terebellidæ the nephridium opens internally,
and that the genital funnel becomes connected with the nephrostome and loses its
primitive opening to the exterior. He considers these organs in this group as coelomo-
ducts.Cunningham2 found a median neural canal in Lanice conchilega, but none in Amphitrite
Johnstoni or Terebellides strcemi.
Ssolowiew8 (1899) gave an account of the Terebellids of the White Sea, the species
on the whole resembling the Norwegian, though he adds Soloivetia Mabngreni, a new
genus and species, and Ampliitrite birulai, a new species, and makes various changes in
the synonymy. His figures, though fairly accurate in most cases, are somewhat deficient
in finish. He places the Terebellids under nine heads, founding the separation of the
groups chiefly on the structure of the cephalic lobe, that of the branchiæ, and on the
arrangement and structure of the bristles and hooks, the genera having the following
order : Poly cirrus, Terebellides, Trichobranchus, Artacama, Solowetia, Amphitrite, Laphania,
Pista.Wollebæk (1912) makes six groups of the Terebellidæ, the first containing Eauchiella
and Lysilla; the,second, Amoea; the third, Terebellides and Trichobranchus; the fourth,
Ereutho, Polydfrus, Leucanste, Streblosoma, Grymoea and Thelepus: the fifth, Leoena,
Artacama, Scione, . Nicolea, Terebella, Pista, Amphitrite and Lanice ; whilst the sixth
includes only Laphania, with, perhaps, Solowetia near it. No exception can be taken to
the first group, both being devoid of hooks, yet the one genus has and the other has not
bristles. The second group is sharply separated from those in front and behind. The
third group is a natural one. The fourth might well be subdivided and the same may be
said of the fifth. Laphania, which constitutes the sixth group, does not appear to require
isolation.
Hessle4 (1917) replaces Malmgren’s classification of the Terebellids, which has been
in use for fifty years, by one of his own in which the nephridia play a prominent part, but
the results do not seem to be commensurate with the trouble, and the grouping of the
genera, e. g. Amphitrite and Artacama, is in some cases unsatisfactory. Most of the
characters are of old standing, but the introduction of the nephridia in the series is new.
His first division has the anterior nephridia smaller than the posterior, or absent, and here
fall Pista, Lanicides, Lanice, Loimia, Nicolea and Polymnia, Neo-amphitrite, Neolepi'sea,
Terebella, Amphitrite and Artacama. He thus more or less reverses the arrangement of
Malmgren, and the foregoing representatives differ materially amongst themselves as to
the details of nephridial arrangement, whilst, as regards the old character of bearing
branchiæ, they all agree. They certainly could all be recognised and separated without
Quart. Journ. Micr. Sci./ vol. xliii, n.s., p. 740.
2 Ibid., vol. xxviii, p. 264.
8 ‘ Annuaire Musée Zool. de Acad. Imp. des Sc. de St. Petersbourg/ t. iv, p. 179,'Taf. x xiii.
* ‘ Zool. Bidrag Uppsala/ No. 5, pp. 149—151.