débris from the haddock-hooks on the 16th September, 1889. The injured specimen had
nine or ten bristled feet. The head showed two broad lobes in front, with a deep median
notch. Only the ceratophore of the median tentacle remained. The lateral tentacles
formed two short subulate organs. The palpi were fairly developed, with tapering tips.
The tentacular cirri had long slender tips, readily distinguished from those of allied
forms, and all these organs were smooth. A pair of black eyes—very widely separated-^
were situated at the posterior part of the head. The teeth of the proboscis were clearly
visible as four hollow, pointed chitinous processes, with a small spur near the base, and
with long horny limbs for the attachment of muscles. The dorsal bristles were recognised
by their characteristic scalariform structure, from three to six or seven rows of spines being
present. They wère more slender than in the adult, and tapered to a delicate tip. The
ventral bristles had the prominent basal spur, and the long slightly curved and more
finely spinous tip. They projected considerably on each side, as became the nectochæte
stage.
The Aphrodita velox of Dalyell (1853) is in all probability this form, its translucency,
irritability, and general aspect being characteristic. His example was scarcely half an
inch long.
Kinberg’s Hermadion (1857) had the following characters :—Head broader posteriçrly.
Posterior eyes distant from the anterior. Elytra fifteen, not covering the posterior
part of the body. Inferior bristles serrate below the apex. Foot elongate. There is
little that is diagnostic in this, and certainly the present genus requires a more precise
definition. His species were quite different from the British, and-came from the Straits
of Magellan.
Ehlers (1864) gave a long and careful description of the species from Quarneo in the
Adriatic, detailing the essential characters, though his figures of the bristles and scales
needed improvement. His specimens were small, only from 7 to 9 mm., and of twenty-
two segments. The ciliated processes on the dorsum of the foot he considered the
external part of the segmental organs ; and as his examples bore reproductive elements
(summer), he was the more certain of the function.of these organs. Haswell and Bourne
have both pointed out, in other species, the true segmental organs, which are on the
ventral surface. Ehlers thought the species had relationship with Kinberg’s genus
Hermadion.
Claparède (1868) published a fairly accurate account of this species from Naples,
pointing out the palpocils on the cilia of the cirri, and the ciliated cushions on the dorsum
of the feet. He also describes the remarkable facility with which the distribution of the
nerves can be followed. Its irritability struck him, and it cast off both scales and cirri.
He, like Ehlers, placed it under Kinberg’s genus Hermadion mainly because the scales
only overlapped in the anterior region of the body.
In his supplement to the ‘Annelids of Naples ’ (1870), the same author recognised
that his Hermadion fragile was Delle Chiaje’s I/ysid/ice communis, which that author
had represented with only the anterior pair of scales, and to which his artist had
added a pair of cirri on every segment—of which the figure shows no less than
about sixty. In this communication Claparède describes the segmental papilla
at the inner border of the foot ventrally, and shows a membrane investing the
developing ova. He could not say that this membrane represented the wall of the
segmental organ ; indeed the absence of cilia inclined him to think it did not. He also
drew attention to certain cell-masses, with yellowish concretions in, the centre, in the
intestinal diverticula—which he thought excrementitious. Prof. Giard agrees with me in
considering the distinctions of this form and 8. communis insignificant.
Marenzeller (1876) found 8. commimis—in the Bay of Muggia at Trieste at a depth
of 18 metres, on Ophiothrix alopecurus—with thirty-three segments, and measuring 10 mm.
His example had fourteen pairs of elytra. He also mentions the advantages of the species
for the study of the nerves of the elytra, and alludes to the characteristic structure of the
bristles.
Langerhans (1879) records large examples (2 cm.) from Madeira. In connection
with the scales he discourses on tactile hairs and rudimentary organs of various animals.
Hornell (1891) found all his specimens as commensals on Echinoderms—one in the
ambulacral groove of Astropecten irregularis, another on Grossaster papposa, and the third
on Ophiothrix rosula. In one the pellucid scales had posteriorly a crescent of orange,
while the first pair had an orange belt all round.
2. S o a l is e t o s u s a s s im il is , McIntosh, 1875.
Specific Characters.—Head similar to that of .8. communist the eyes occupying the
same position, and the larger anterior pair having lenses. Median tentacle long, smooth,
slightly dilated below the filiform tip ; lateral tentacles short, also slightly dilated below
the tip. Palpi smooth. Tentacular cirri similar to the median tentacle. Body narrow
and elongated, with a brownish-black median band from the nuchal collar to the posterior
end. I t is widest at the posterior part of the proboscidian region, though even there
less than a third of the breadth of the dorsum. Segmental eminence prominent, but a
special papilla could not be made out. Scales even more delicate and transparent than
in 8. communist minutely punctate on the under surface. The outer and posterior borders
and neighbouring surface have short clavate cilia—less numerous than in the former
species. The finely branched nerves and nerve-endings are similar. From the dorsum
the tips of the feet are blunt, and viewed laterally the dorsal eminence for the bristles
is large, while the spine has a broader border of granular epiderm. The dorsal bristles
are smaller than in 8. communis, slightly curved, the spinous rows being less prominent
and covering a shorter region of the bristle. The tip is bluntly rounded, bearing a minute
terminal claw and a small secondary process with a notch between. The ventral division
shows a broad terminal lobe with a bluntly rounded margin in front of the tuft of
bristles. The latter, as in 8. communis, has the distal end of the shaft expanded, with a
small spinous collar, and from this the spinous region, with a slight bend to the dorsum,
tapers to the tip, which turns bluntly round to the spiked side and ends in a small hook;
then, after an edge directed obliquely backward, a secondary process, lateral in position,
occurs. The rows of spines are extremely fine. The dorsal cirri are apparently shorter
than in the previous species, but of a similar shape—smooth, with a long filiform process
at the tip. Only one was observed.