occurs, and by which the nerve-supply to the cells and protoplasmic contents of the
sensitive organs takes place. He also notes that the muscular fibres show no striae,
either transverse or longitudinal, and that the elytra, after Haswell’s description, have a
double cuticle superiorly and inferiorly, two layers of cells, and an intermediate fibrous
layer. They contain no cavity, but have a nervous plexus. They are evidently organs
of considerable sensibility. Amongst other interesting points he refers to the nerve-
supply of the palpi and dorsal cirri with their ganglia near the base of the terminal
division, the nerve-trunk in each breaking up into a tuft of cells in this region.
Family III.—P olynoidj:.
Body more or less elongate; no facial tubercle, convex cephalic lobe; the base of
the tentacle arising from the middle anteriorly; two lateral tentacles; four eyes; palpi
elongate. Peristomium, bearing the first, foot, with long dorsal and ventral cirri,
and the ventral cirrus of the next segment long. Pharynx exsertile, muscular,
Fig. 19.
Alimentary apparatus of Harmothoe imbricate.—A. W.
cylindrical, with papillae round the margin; horny jaws. Intestinal caeca shorter than
in the ApJvroditidx, slightly branched; first foot bearing only a few minute bristles
conforming to the dorsal type. Scales twelve to thirty-five pairs or more; segments
carrying these devoid of cirri. Segmental organs (nephridia) opening ventrally on a
papilla near the bases of the foot; nerve-cords within the granular layer of the epiderm
and between the oblique muscles. Dorsal bristles with more or less tapered simple tips ;
ventral bristles with simple or bifid hooked tips. Development by trochophores. The
general arrangement of the body-wall in this family may best be understood by consulting
the accompanying figure.
Fia. 20.
Section of body-mil of Poly »of m lo p a d r im , S»v„ ir. the line of a median donnai papilla (a), about the
middle of the body, b, bases of dorsal bristles; V , bases of ventral bristles; c, ova scattered in the
various parts of the perivisceral (coelomic) space {p v ) ; d, intestine; d', portions of intestinal casca; dm,
dorsal longitudinal muscles; bn, band of longitudinal muscular fibres above the nerve-area; om, oblique
and nearly vertical muscles; vm, v entral longitudinal muscles; nc, nerve-cords; dv, dorsal vessel with
mesenteries a t side; v, ventral vessel with mesenteries; vc, ventral cirrus; so, segmental organs
(nephridia). The dorsal cirrus is n o t shown, nor the perivisceral corpuscles. The drawing was made
by Dr. Masterman from a somewhat contracted example.
Many authors, such as Audouin angljMilne Edwards, Johnston, (Ersted, Grube,
Dé Quatrefages, and Marenzeller, following Savigny, regarded the Polynoidæ as one or
more genera of the family Aphroditidæ.
Kinberg, on the other hand, gave them the position of an independent family, or
indeed two, if we include Iphione, with the characters indicated in the subsequent
summary. In this he was followed by Malmgren and Théel. Claparède, again, varied the
latter arrangement a little by making them his second Tribe, an equivalent position.
Savigny (1820) placed the Polynoidæ as a genus of his family Aphroditæ under the
Nereids, the general characters being the oval or oblong body, with its elytra, which
were typically a dozen pairs, branchiae (which he says are easily recognised), head and
its median unpaired, and external antennæ, four eyes, and armed papillose proboscis.
With the exception of the remarks on the branchiae his description is fairly good.
By Audouin and Milne Edwards (1884) the Polynoidæ were distinguished from the
Aphroditidæ by the number of their antennæ, by the armature of the proboscis, and by the
alternation of scales with oirri. Some have large scales completely covering the dorsum,
others have them so minute as to leave the dorsum more or less bare, and in some oases
they are vesiculate. The antennæ are five or rarely four; probosois armed with large
jaws. The simple branchiæ occur with the cirri. The first pair of feet terminate in long
tentaoular cirri ; the appendages of the last segment form styles. They frequent banks