. A conchological manual. Shells. 12 INTRODUCTION. stances, then they are named " Petricolce"—some of these latter form the holes in which they live by corroding or eating away the stone. A section of these form the family of " Li- thophagidce" or stone-eaters, of Lamarck. Others,again, take up their parasitical abode in the bodies of animals, and feed upon their substance ; as for instance, the Stylifer, which is found in the vital part of star-fish, and Coronula, and Tubici- nella, found buried in the skin of the whale. LOCOMOTION—Attached, Unattached. A much more subordi
. A conchological manual. Shells. 12 INTRODUCTION. stances, then they are named " Petricolce"—some of these latter form the holes in which they live by corroding or eating away the stone. A section of these form the family of " Li- thophagidce" or stone-eaters, of Lamarck. Others,again, take up their parasitical abode in the bodies of animals, and feed upon their substance ; as for instance, the Stylifer, which is found in the vital part of star-fish, and Coronula, and Tubici- nella, found buried in the skin of the whale. LOCOMOTION—Attached, Unattached. A much more subordinate source of distinction arises from the freedom or attachment of the shells. Some of them float or walk freely in their natural element; others are fixed or attached to foreign bodies. Among those which are attached, there is again a difference as to the mode of attachment. Some are united to foreign bodies by means of a glutinating sub- stance, secreted by the animal, and joining part of the surface of the shell to that of the stone, coral, or other substance. In this way shells are fixed to each other in groups; this is the case with the Spondyli among bivalves, and the Serpulse among univalves. M. de Blainville applies the term " Fixa? to these shells. Others are kept in a particular place by means of a Byssus or Tendinous fibrous line or bunch of silky hairs, acting as a cable, and allowing the Mollusc to ride as it were at anchor. This Tendon is connected with some part of the animal from which it passes through an opening or hiatus in the shell, as in the Terebratula and the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Sowerby, G. B. (George Brettingham), 1812-1884. London : Henry G. Bohn
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