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 A HISTORY OF NORFOLK V. GEPHYREA 22. Phascolosoma vulgare (Blainville). Body cylindrical ; skin yellowish, smooth, tough, shining. Proboscis about half the length of the body, and invaginable into the latter ; its anterior swollen part provided with a diffuse band of small brown booklets, and with 1 6 circumoral tentacles. Length 5-6 inches. Burrows in sand. VI. CH.ETOGNATHA 23. Sagitta bipunctatay Quoy and Gaimard. Body cylindrical, elongated, transparent ; provided with 2 pairs of lateral fins ; tail fins small. Length f inch. Lives freely floating in the sea. Mouth armed with lateral hooks. VII. POLYZOA Animals of minute size, provided with a circlet of ciliated tentacles, and forming exten- sive colonies, either reticulate, encrusting, or arborescent. The lower part of the body of each individual (or zoo/W) has usually a horny or calcareous skin, which forms a box or tube (called the zocecium), into which the delicate upper portion can be quickly withdrawn for purposes of protection. In the Cheilostomes the ' mouth ' of this box can be closed by a movable lid (the operculum) which in certain modified zooecia of the colony is converted into a snapping beak (avicularium) or a long slender spine {vibraculum) for cleansing the colony. Nomenclature : Hincks, British Marine Polyzoa, 1880. I. CHEILOSTOMATA 1 . Eucratea chelate (Linn.)., Colony composed of a creeping base (usually lines of decumbent zooecia) and of delicate branching shoots. Zooecia in single rows, white, subcalcareous, expanding upwards ; aperture oblique, margin unarmed ; often bearing a short tubular appendage below the aperture. Yarmouth, on Amathia and Vesi- cularia (Harmer). 2. Menipea ternata (Ell. and Sol.). Colony arborescent, forming delicate white tufts with curling branches on the larger Hydroids {Hydrallmania, Sertularia, etc.) to which it binds itself by numerous tendrils. Zooecia tapering below, united in sets of three ; overhanging fan-shaped spine, and 2 or 3 terminal spines. Large lateral avicularia. Off Hasborough (P.). 3. Scrupocellaria scruposa (Linn.). Colony arborescent, forming stiff bushy tufts of a white colour. Zooecia in double series. Aperture large, elliptical, with 2 slender spines only on each side above. Under stones and on weeds, zoophytes, etc. OfiF Hasborough (P.), Yarmouth (Harmer). 4. Scrupocellaria scrupea, Busk. Like the preceding, but the aperture oval, and protected by an overhanging opercular plate, as well as by 3 spines on the outer margin above, and i, or occasionally 2, on the inner. OfiF Hasborough (P.). 5. Scrupocellaria reptans (Linn.). Colony forming stiff ragged sprays. Mar- ginal spines as in S. scrupea, but the opercular spine is branched and antler-like. Avicularia and vibracula present in all three species. Not yet recorded, but generally common between tide-marks. 6. Bicellaria ciliata (Linn.). Colonies pearly white, in delicate feathery tufts. Zooecia biserial, alternate ; the ellipti- cal aperture guarded by exceedingly long marginal spines, viz. 4-7 above, 1 centrally below, and i or 2 on the back. Yarmouth, common (Harmer). 7. Bugula plumosa (Pallas). Colony in tall feathery tufts, with fan-like branches spirally arranged. Colour, when alive, bright buff. Zooecia biserial. Aperture large, with a single spine at the top. Avicu- laria (' birds' heads ') very small. Recorded off Hasborough and Lowestoft (P.), Yarmouth (Harmer). 8. Flustra foliacea (Linn.). The ' sea-mat.' Colony erect, in large flat fronds of a brown colour, deeply divided. Aperture with 2 marginal spines on each side and often i at the top. Abundant off« shore and thrown up in quantities on the beaches (P.). 9. Membranipora lacroixii, Audouin. Colony forming a thin gauze-like crust over shells and stones. Zooecia oval or elongated ; aperture oval, occupying the whole of the front ; margin thickened ; spines usually I pair above, rarely numerous (11), and then very delicate and pointing inwards. Abun- dant on dead Mytilus shells and other objects, Yarmouth (Harmer). 84
 * aperture ' subterminal, oval, protected by an