. Elements of conchology / Prepared for the use of schools and colleges. Mollusks. TRIGONIA.—MUSSELS. 79 on each face {jig. 99), and entering between four plates of the left (opposite) valve, like- wise crenulated upon their internal face only. There is but one living species known, — Trigonia pectinata,—which in- habits the seas of j^g, pectinata. New Holland; exter- nally, it has the aspect of Pecten without ears. 21. In the Family of Mytilacea, the mantle is widely open in front, as in the Ostracea, but there is a particular opening for the escape of excrement; this orifice, ho
. Elements of conchology / Prepared for the use of schools and colleges. Mollusks. TRIGONIA.—MUSSELS. 79 on each face {jig. 99), and entering between four plates of the left (opposite) valve, like- wise crenulated upon their internal face only. There is but one living species known, — Trigonia pectinata,—which in- habits the seas of j^g, pectinata. New Holland; exter- nally, it has the aspect of Pecten without ears. 21. In the Family of Mytilacea, the mantle is widely open in front, as in the Ostracea, but there is a particular opening for the escape of excrement; this orifice, however, is not prolonged into a tube, as in the families that follow, and there is no special aperture for the passage of water for the purpose of respiration. There is always a distinct foot, and the valves are approxi- mated by the action of two adductor muscles. The Mytilacese resemble each other sufficiently to be commonly known under the single name of Mussels, but they require, never- theless, to be separated into several genera, the most important of which are, Mussels properly so called,—Mytilus,—Anodonta, and Unio. 22. Mussels properly so called—Mytilus—abound on the rocks of the coast of France and of other countries, where they live fixed by the by^sus, and generally closely united to each other. Their shell is shut, and its valves, triangular in form, are equal, arched and united by a narrow ligament on the side of their acute angle. The mouth of the animal is situate near the summit of the shell, the opposite extremity of which gives passage to the byssus; the anus also is placed near the hinge; and opposite to this orifice there is a particular opening or small tube formed by the mantle; towards the round angle of the shell, where the water necessary for respiration passes, the edge of the mantle is fringed; and the foot is slender, cylindrical, and furnished behind with a silky byssus. Mussels are generally eaten as food, but they sometimes occasion
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectmollusks, bookyear184
