Fig. 164.—Aphrodite aculeata L. (from Règne Animal). Nat. size. c, Neuropodial chaetae; p, palps; 1, iridescent bristles; 2, stiff chaetae; 3, felting bristles of notopodium.
Aphrodite.—The fifteen pairs of elytra, arranged as in Polynoë, are concealed by a "felting" of hair-like chitinous threads arising from the notopodium (Fig. 139, p. [268]). A. aculeata L.—The "sea-mouse" is one of the most beautiful of the Polychaetes. The small tentacle is very readily detached; the palps are very long; the parapodia of the peristomium are directed forwards so as to form lateral lips; and its cirri are not especially modified (see Fig. 132, p. [260]). The body, which measures 3 to 6 inches, consists of thirty-five to forty segments, and is broadest in the middle, the last dozen segments being very small; the body terminates in a point. Some of the notopodial chaetae are brilliantly iridescent, and give the worm its characteristic coloration. It is fairly common in the coralline regions, and is frequently thrown ashore after storms. Atlantic and Mediterranean.
In Hermione the "felt" is absent, so that the elytra are exposed. H. hystrix Sav. occurs in ten to thirty fathoms of water all over the British area and Mediterranean. It resembles in its general appearance a fat Polynoid, with strong chaetae. Laetmonice filicornis Kinb. also occurs on our north-west coasts, and L. producta Gr. has been dredged in 500 fathoms off the west coast of Ireland; it has been recorded also from Kerguelen and from Japan, so that it has a very wide distribution.[[373]]
Sub-Fam. 3. Acoetina.[[374]]—The long, vermiform body has some thirty-nine to ninety-three pairs of elytra, placed on every alternate segment throughout. It is represented in the British area by Panthalis from 75 fms., which forms a tube of black mud.
Sub-Fam. 4. Sigalionina.—This sub-family includes forms with a long, vermiform body; anteriorly the elytra are on alternate segments, up to the twenty-sixth, and posteriorly on every succeeding segment; "gills" here coexist with elytra; cirri are absent. The prostomium in Sthenelais Kinb. has a median tentacle, which is absent in Sigalion Aud. and Edw. Sth. boa Jnstn. is common off our coasts near low-water mark, where it burrows in the loose sand with rapidity. It is an elegant worm, and may attain a length of 8 inches, though it is generally smaller; it is narrow, flat, and only slightly tapering at each end; the elytra, which may be more than a hundred pairs, are greyish or slightly brownish, some being lighter than others; the margin is fringed with simple processes (which in Sigalion are pinnate). Atlantic and Mediterranean. In Psammolyce the elytra are covered with sand grains. British and Mediterranean.
Fam. 4. Phyllodocidae.—The members of this family make use of the foliaceous cirri (Fig. 136, F) in their very active movements. The rounded prostomium bears four or five tentacles; there are four long peristomial cirri on each side (see Fig. 134, E).
Sub-Fam. 1. Phyllodocina.—The body is elongated, with numerous segments; the eyes are small; the chaetae are jointed; the dorsal and ventral cirri are foliaceous; the pharynx is covered with papillae externally, but contains no "jaws."
Phyllodoce has a more or less depressed body; four prostomial tentacles; four pairs of peristomial cirri. P. lamelligera Jnstn.[[375]] (the "paddle-worm") may reach a length of 24 inches, but is usually 8 to 12 inches long and ½ inch across. The general colour is bright bluish-green or yellowish-green, with metallic iridescence; the parapodia olive-green or brown, the sensory processes yellow. It lurks, during day, under stones and shells, etc., in the Laminarian zone. The green egg masses, so frequently referred to as belonging to Arenicola, are laid by Phyllodocids.[[376]]
