Zoologically the oyster is known as _Ostræa edulis_. Its outward appearance is familiar to even very landward people, and no human engineer could have invented so admirable a home for the pulpy and headless mass of jelly that is contained within the rough-looking shell. The oyster is a curiously-constructed animal; but I fear that, comparatively speaking, very few of my readers have ever seen a perfect one, as oysters are very much mutilated, being generally deprived of their beards before they are sent to table, and otherwise hurt, both accidentally in the opening and by use and wont, as in the case of the beard. Its mouth—it has no jaws or teeth—is a kind of trunk or snout, with four lips, and leafy coverings or gills are spread over the body to act as lungs, and keep from the action of the water the air which the animal requires for its existence. This covering is divided into two lobes with ciliated edges. Four leaves or membranous plates act as capillary funnels, open at the farthest extremities. Behind the gills there is a large whitish fatty part enclosing the stomach and intestines. The vessels of circulation play into muscular cavities, which act the part of the heart. The stomach is situated near the mouth. The oyster has no feet, but can move by opening and closing its shell, and it secures food by means of its beard, which acts as a kind of rake. In fact the internal structure of the oyster, while it is excellently adapted to that animal’s mode of life, is exceedingly simple.