Note: Information is dated. Do not rely on it.Shark. The general name for a group of cartilaginous fishes, celebrated for the size and voracity of many of the species. The form of the body is elongated, and the tail thick and fleshy. The mouth is large, and armed with several rows of compressed, sharp-edged, and sometimes serrated teeth. The skin is usually very rough, covered with a multitude of little osseous tubercles or placoid scales. They are the most formidable and voracious of all fishes, pursue other marine animals, and seem to care little whether their prey be living or dead. They often follow vessels for the sake of picking up any offal which may be thrown overboard, and man himself often becomes a victim to their rapacity. The basking shark is by far the largest species, sometimes attaining the length of forty-five feet, but it has none of the ferocity of the others. The white shark is one of the most formidable and voracious of these fishes. It is rare on the British coasts, but common in many of the warmer seas, reaching a length of over thirty feet. The hammer-headed sharks which are chiefly found in tropical seas are very voracious, and often attack man. They are noteworthy for the remarkable shape of their head, which resembles somewhat a double-headed hammer, the eyes being at the extremities. Other forms are the blue shark, fox shark, or thresher, and the mackerel shark.