Sub-Order 4. Capitelliformia.
Fam. Capitellidae.[[389]]—Capitella capitata v. Ben. occurs pretty frequently in the sand under stones near low tide-mark. It is a red worm, about 1½ to 2 inches long, greatly resembling a Tubificid Oligochaete. It may readily be distinguished from other Polychaeta by the strong genital chaetae in the male, which replace the notopodial chaetae of segments 8 and 9; those in the former segment are pointed backwards, and in the latter forwards. There is but a single pair of generative ducts in either sex in the eighth segment. North Sea, Mediterranean.
Notomastus latericeus Sars is a longer worm, living in shallow water, off our coast and in the Mediterranean. The anterior twelve segments are wider than the rest of the body. The notopodial chaetae of the anterior segments of the hind body form a ring. Dasybranchus caducus Gr., which occurs in the Mediterranean, but not on our coast, reaches a length of 2 or 3 feet. It has gills on the hinder segments above the neuropodia.
Mastobranchus Eis. is found in the Mediterranean.
Sub-Order 5. Scoleciformia.
Fam. 1. Opheliidae.—Comparatively short, rather ugly worms of a pearly colour, no prostomial processes: parapodia obscure. The family is represented in British waters by four species, occurring in shallow water.
Ammotrypane aulogaster Rathke, is about 2 inches long; the nearly cylindrical body has a ridge running along each side below the chaetae. The conical prostomium is tipped with a small knob, and carries at each side a ciliated pit (Fig. 144, p. [273]). Every segment, except the first chaetigerous, is provided with a filamentous gill (dorsal cirrus). The segmentation is very obscurely marked, for internally there are only three complete septa, placed far forwards. The intestine is bent upon itself. In Ophelia limacina Rthk. the gills commence in the eighth segment, and the longitudinal ridge does not extend in front of this segment. The worm is about 1½ inches long, and occurs between tide-marks. Travisia forbesi Jnstn., North Sea. Polyophthalmus pictus[[390]] Duj. is very abundant at some parts of the coast. There are two bundles of chaetae on each side of every segment; each bundle contains three chaetae, of which only one projects to any distance. Paired eye-like spots exist on the sides of twelve segments. The worm is about an inch in length.
Fam. 2. Maldanidae (= Clymenidae).—Represented on our coasts by four fairly common species. They form sandy tubes, which are embedded in the sand with a short portion projecting. In some places they are so abundant that at low water the sand has quite a rough appearance. The prostomium is frequently truncated and depressed, and is always fused with the peristomium. A horny plate may be developed on the upper surface of the head, and the skin at the side of the prostomium is frequently raised into a more or less prominent fold. The hinder end of the body carries a funnel surrounding the anus. There are no gills or sensory processes on the body. Some of the segments towards the middle of the body may be longer than the rest. Peculiar serrated hooks of characteristic shape constitute the neuropodial "torus." The buccal region is eversible.
Nicomache lumbricalis Fabr. is a rosy-pink worm with white spots anteriorly; the chaetigerous ridges are red. The worm consists of twenty-six segments, and measures 2 or 3 inches. It is very narrow and readily breaks in pieces. The prostomium is laterally compressed; the anal funnel is fringed with a number of short equal processes. Under stones in the Laminarian zone.
