Page:Natural History, Mollusca.djvu/24

12 bulk of the shell; yet let the creature be disturbed, and the whole is suddenly withdrawn into the cavity, so completely that not a trace of it is visible. "When shrunk within its shell," observes Dr. Johnston, "you might well deem any animal that could hide itself there, all too small and weak to carry about a burden larger and heavier than itself,



and that safety might be here advantageously exchanged for relief from so much heaviness of armour, and from such an impediment to every journey. There is in my small cabinet a fine specimen of Cassis tuberosa, which measures fully ten inches in length, and upwards of eight in breadth, another of Strombus gigas is nearly one foot in