If a pair of the shells from which the delicious morsel has been extracted, be taken in the hand, it may be noticed that one is much thinner, smoother, and flatter than the other; this is the side most exposed to the action of the water; the rougher and rounder side is that which is attached to the rock, or other substance to which the animal forms an attachment, that is usually life-long. The two portions of the shell are joined together by a hinge of curious workmanship, which is formed of the inner layer of the shell, and strengthened by a ligament which is wonderfully elastic; when the shell is drawn together by the abductor muscles, the ligament is at full stretch, and as soon as they relax at all, it contracts, and causes the shell to gape. This process is repeated as often as may be necessary for the safety and sustenance of the animal within, whose mouth is situated at the narrowest part of its habitation, namely, near the joint of the hinge, which connects its upper and under shell. The anatomical structure of the Oyster is more perfect than would be supposed, from its apparently low state of organization; it has a heart, liver, and intestinal canal, and a bag near the mouth, which answers the purpose of a stomach. Its breathing organs are gills, closely resembling those of most other fish; it has little vessels which convey the bile from the stomach to the liver, and may perhaps be subject to bilious attacks, as well as those who swallow this curious piece of organization at a mouthful, without thinking at all of the goodly structure they are demolishing. There is the tiny heart with its series of blood-vessels, just as perfect as in the larger animals. There are the nerves in the shape of minute feelers, which appear to be acutely sensible not only of actual contact with foreign bodies, but also of sounds and movements from without. A very nice sense of feeling appears to reside in what is called the beard, in scientific language _bissus_; this is a kind of double fringe to the two lobes of the mantle, or sac, as it is called, which envelopes the body of the animal, and floats free from the shell, except just at the part nearer the valve where it is attached. We have just spoken of the beard of the Oyster, and this reminds us of a conundrum which may serve to amuse our readers, and enliven these dry details a little. Why is an Oyster the most anomalous, that is strange, contradictory, creature in existence? Do you give it up? Well then it is because “It wears a beard without any chin, And leaves its bed to be tucked in.”