The structure of these animals is very remarkable. Their body is nearly cylindrical, and, in some of the species, entirely covered with a fleshy sheath; in others the sheath reaches only to the middle of the body. They have eight arms, or rather legs, and in general two feelers, much longer than the arms. Both the feelers and arms are furnished with strong circular cups or suckers. The mouth is hard, strong, and horny, resembling in texture the beak of the parrot. The body is of a jelly-like substance, and usually covered with a coarse skin, having the appearance of leather. This skin contains cells of different colours, which are capable of changing their relative position, so that the Cuttle-fish is able to change the colour of its skin. By means of the numerous circular cups or suckers with which the arms are furnished, they seize their prey, and firmly attach themselves to the rocks. Their adhesive power is so great, that it is generally more easy to tear off the arms than to separate them from the substance to which they are affixed: if the arms happen to be broken off, they are soon reproduced. The size to which this creature grows has been variously stated; and, although evidently exaggerated by some authors, it undoubtedly attains to a very considerable magnitude. When attacked in its own element, it has been known to overcome a large dog. Its jaws are extremely strong and powerful, and with its beak it can crush in pieces the shells of the fish on which it feeds. In the body is a bladder filled with a dark inky fluid, which it emits when alarmed, and which not only tinges the water so as to conceal its retreat, but is so bitter as immediately to drive off its enemies. This inky fluid, when dried, forms a very valuable colour, used by artists, and known as Sepia.
The bone, or calcareous plate of the Sepia Officinalis, a species common on our coasts, is a well-known substance, and is much employed in the manufacture of toothpowder; and by silversmiths for moulds, to cast their small work, such as rings, &c. It is also converted into that useful article of stationery, called pounce.
THE POULPE, (Octopus vulgaris,)
Has only eight arms, the two long tentacles of the Sepia being absent. It is found on our coasts, and is especially abundant in the Mediterranean, where it is regularly brought to market as an article of food.
THE ARGONAUT, OE PAPER NAUTILUS,