Elements of zoology, or, Natural Elements of zoology, or, Natural history of animals / ed. by Reese elementsofzoolog00rees Year: 1849 CLASS CONCHIFERA GENERAL DESCRIPTION. 467 tube leading to it, the orifice of which is furnished with four tentacula or feelers. To the right of this is seen the long and complicated intestinal tube, with the liver lying in separate masses amongst its folds. And nearer the large end, the cavity of the shell is chiefly occupied by the ovarium, in which the eggs are formed. Close to this is the powerful adductor muscle, by which the valves can be drawn togeth


Elements of zoology, or, Natural Elements of zoology, or, Natural history of animals / ed. by Reese elementsofzoolog00rees Year: 1849 CLASS CONCHIFERA GENERAL DESCRIPTION. 467 tube leading to it, the orifice of which is furnished with four tentacula or feelers. To the right of this is seen the long and complicated intestinal tube, with the liver lying in separate masses amongst its folds. And nearer the large end, the cavity of the shell is chiefly occupied by the ovarium, in which the eggs are formed. Close to this is the powerful adductor muscle, by which the valves can be drawn together with considerable force. The intestinal tube is seen to terminate near the open- ing at the posterior (or right hand) extremity of the shell, which discharges its contents, and serves for the exit of the respira- tory current. Interior of Mussel: a, right valve ; b, left valve; c, hinge, d, stomach; e, ten- tacula ; f, foot; g, byssus; h, branchial orifice; i, vent; &, termination of intestine; I, liver ; m, gills ; n, adductor muscle; o, ovarium. 810. The foregoing description will apply, with slight varia- tions, to the structure of almost all Conchifera; but we have now to notice two organs, which are absent in some, and in others more largely developed than in the present instance. From the lower part of the shell passing out between the sepa- rate edges of the mantle, is seen the foot, a fleshy muscular organ, somewhat resembling the tongue of higher animals, and not con- taining any hard support, or being protected by any envelope. This foot, which is the only special locomotive organ possessed by the mollusca of this class, serves a great variety of purposes, sometimes enabling the animal to leap with considerable agility along a hard surface, sometimes being used to bore into the sand or mud, and sometimes serving only to affix the animal to some firm support. From the base of this foot there proceeds, in the muscle, a band of hair-like filaments, forming what is


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