Four species of Sturgeon are commonly known. The Caviare Sturgeon, the Huso or Isinglass Fish, the Great Sturgeon and the Common Sturgeon. The Caviare Sturgeon is the best known in this country, as well as in European waters, and it is the most eagerly sought after by fishermen because it is from the roe of this Fish that the noted delicacy called caviare is made, which until recent years was confined principally to Russia, but which is now well known and consumed on both continents. What is known as the Isinglass Fish, besides supplying us with roe similar to that of the Caviare Sturgeon, also furnishes a valuable commodity known as isinglass. The Common Sturgeon abounds in the North Sea and the Mediterranean. It is usually about two yards to seven feet long, but has been known to attain the length of ten or twelve feet. It is remarkable for the number and form of the osseous plates or scales, which cover the body like so many bucklers. It has no less than twelve to fifteen of these rough bony plates, relieved by projections, which are pointed in the young, and soften down with age. On each side is a row of thirty to thirty-five of these triangular plates, separated from each other by considerable intervals. The head is broad at the base, gradually contracting towards the point, and terminating in a conical nose. The mouth is large and considerably behind the extremity of the nose, and its jaws, in place of teeth, are furnished with cartilages. Between the mouth and the nose are four slender and very elastic barbs, or wattles, like so many little worms. It is claimed that these wattles attract small Fishes to the jaws of the animal, while it conceals itself among the roots of aquatic plants. In the sea the Sturgeon feeds on Herrings, Mackerel, Cod-fish and other Fishes of moderate size. In the rivers it attacks the Salmon which ascend them about the same time. Mingling with them, however, it seems a giant. Its flesh is delicate, and in countries where they are caught in quantities it is dried and preserved. The Great Sturgeon, which sometimes exceeds a thousand pounds, is only found in the rivers which flow into the Caspian and Black seas. The Volga, the Don, and the Danube produce the largest species. THE CHIMERA. [Illustration: CHIMERA]