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protected by a hard shell, Univalve or Bivalve. Taking first now the Univalves, which have a distinct head, eyes, and tentacles, the mouth being armed with jaws, we find that Cuvier has arranged them into three classes, the animals belonging to the first of which are termed Cephalopoda (from Cephale the head, and poda feet), because their feet, or rather arms, which are attached to the head form a circle around the mouth; the Cuttle fish is a familiar example, and its shell, which is internal, as in almost all comprised in this class, is constantly thrown upon our shores;—the beautiful little discoidal chambered shell of the Spirula, is not uncommon on the Warrnambool and other of our coasts, the animal itself would indeed be a prize, for although an inhabitant of all the warm seas, it is not often met with.
The animals of the second class, or Gasteropoda, of which the common garden snail is a good type, creep by the successive expansion and contraction of their broad muscular foot, which is formed by the under side of the body, and thus the name of the class is obtained from gaster, the belly, and as before poda, feet. Some breathe air, (pulmonifera), others water (branchifera.) Many of the individuals of the latter division close their habitations with a horny or calcareous covering called an operculum, and it presents strange modifications of structure; we find it in some spiral, in others concentric, and occasionally claw-shaped; that of a Natica found on the Western Coast, is commonly used as card counters, and we have seen them polished and tastefully mounted as wrist studs and shawl pins.
