First, then, it belongs to the class _Conchifera_; this is a word which we must stop to examine a little; it seems to come from the Latin _concha_, which means a shell-fish with two shells, in other words a bivalve mollusk. Second, our Oyster belongs to the class _Pectinidæ_. Now _pecten_ is the Latin for a comb, and this class includes those bivalve shells whose edges are toothed, or, as it is said, _pectinated_; in the scallop and the cockle shells this peculiarity is more observable than in those of other members of the class, and these form the typical, or so to speak, pattern genus, _pecten_. Thirdly, the Common Oyster is a _Monomyarian Conchifer_. Ah! that’s something like a name for the acephaloid monarch! Look at these two words, _mono-myarian_, _di-myarian_, you know of course that mony-syllable means one syllable, and dis-syllable means two. You sometimes hear of a person who leads a _monotonous_ life, and you think perhaps of the Oyster shut up in his shell all alone, _one_ by himself; this notion you now know to be a false one; although it is true that he has but one abductor muscle, and therefore belongs to the division of the _Pectinidæ_ family called _Monomyaria_, while the Pearl Oyster has two, and therefore belongs to that termed _Dimyaria_. If, as they say, there is reason in the roasting of eggs, surely there must be in the names given to the classes and divisions of shells. We hope to have succeeded in making the why and the wherefore in this case somewhat plain;—_one_—_two_—and away we go out of this maze of hard names. But what about the abductor muscle, above spoken of? well, this must be explained; _abduce_, coming from the Latin _abduco_, means to separate, to draw away, hence we have _abduction_. During the life of an Oyster, the usual and natural state of the shell is that of being kept open for a little distance, to allow the water necessary for its nourishment and respiration to flow in and out; but as a security against danger, it was necessary to furnish the animal with the means of rapidly closing the shell, and retaining the valves in a closed state. These actions being only occasional, yet requiring considerable force, are effected by means of a muscular power, for which purpose one or two, or sometimes more strong muscles are placed between the valves, their fibres passing directly across from the inner surface of one to that of the other, and firmly attached to both, and these are called the abductor muscles, because their office is to draw or pull; how strongly they do this those whose business it is to open Oysters can best tell; if the animal within were not alive, the process would not be a difficult one, as in that case the muscles would be relaxed, and the shell would come open of itself, so that actually people who eat Oysters directly they are opened, swallow them “all alive-O!”