It would seem that, in view of the present failure of the foreign markets, vigorous steps should be taken to encourage the consumption of fish in this country, and so preserve this valuable industry from ruin. A national scheme of development should be inaugurated, having for its objects, (1) the systematic exploitation of local and periodic coastal fisheries; (2) the discovery of methods of preserving for future consumption fish that cannot be disposed of just when it is caught; (3) the education of the public to use more freely the large supplies of excellent fish food that are available at our very doors. CHAPTER II CHARACTERISTICS AND HABITS OF FISHES Fishes are the most primitive vertebrate, i.e. backboned, creatures known. All reptiles, birds, and animals have gradually evolved from fish-like ancestors by a series of age-long processes, the stages of which are recorded in fossilized remains that are found in various rock strata throughout the world. A fish lives exclusively in water. It has no lungs, but extracts oxygen from the water as it passes over the surface of its gills. Instead of limbs, it has fins, with which it balances itself and propels itself through the water. Its skin is either bare, e.g. the cat fish, or is covered with scales, e.g. the herring, or with bony plates, e.g. the sturgeon. The skin of certain sharks is studded with minute teeth and produces, when cured, the well-known shagreen leather. In nearly all cases the skin of fishes is liberally supplied with small glands which constantly produce a lubricating mucus. This mucus greatly reduces friction between the fish and the water through which it moves. The body of a fish is adapted to move swiftly and smoothly through the water; it is shaped more or less like a torpedo, but this form is greatly modified in different species. Certain species of fish living at the bottom of the sea, for example skates and rays, have become flattened, as though by a pressure applied vertically downwards. Others, for example plaice, flounder, sole, appear to have been flattened sideways. In the various members of the eel family, the body is greatly elongated. [Illustration: FIG. 1] The body of a fish is generally coloured and marked in such a way that it becomes practically invisible when seen from above or below, the under-surface being silvery white, and the upper surface generally olive or blackish-green. Sometimes, as in the mackerel, the upper surface is mottled, resembling rippled water.