"Most of these species are straight, but others of the family contract after death, so as to form a grotesque resemblance to a horse in miniature. These form the genus Hippocampus, and from their shape are generally called Sea-horses. Hippocampus brevirostris (the short-nosed Sea-horse) is occasionally met with on the British coast. It is from six to ten inches long, the body much compressed, short and deep; the whole length of the body and tail divided by longitudinal and transverse ridges, with tubercular points at the angles of the intersection. The snout is slender, and the tail long, quadrangular, and terminated in a naked or finless tip. When swimming about, the Hippocampus maintains a vertical position, but the tail is ready to grasp whatever meets it in the water; it quickly entwines in any direction round weeds or other objects, and darts at its prey with great dexterity." 6. PLECTOGNATHI (Plaited jaw). [Illustration: FIG. 43.--THE SUN-FISH (Orthagoriscus).] The Sea Porcupine (Diodon hystrix) belongs to this order. These Fish are of a peculiar thick rounded form, and occasionally inflate their stomachs with air, which makes them almost spherical, in which state they float with the belly upwards, and being covered with spines, present rather a formidable object to attack; the flesh is unwholesome, and, it is said, the liver is violently poisonous; some of the species of this fish are phosphorescent, and from this appearance they derive the name of Sunfish, as they shine very brightly in the dark. The short Sunfish (fig. 43) turns round as it swims; it is very large, sometimes weighing from three to four hundred pounds. They yield a considerable quantity of oil, for which they are caught. Their jaws are not divided into teeth, but consist each of a single piece; they live upon seaweeds and various crustaceans. The Cartilaginous Fishes are divided into three orders. 1. STURIONES (Sturgeons). [Illustration: FIG. 44.--THE STURGEON (Accipenser sturio).] Sturgeons (fig. 44) are inhabitants of the northern seas, but are occasionally found in our rivers. They have rows of bony plates imbedded in the skin; they sometimes attain the length of twenty feet, but are usually from six to eight feet long. Isinglass is made of the swimming bladder of the Sturgeon, and the roe (dried and salted) forms the "Caviare." 2. PLAGIOSTOMI (Wide-mouthed). [Illustration: FIG. 45.--THE SHARK (Carcharias vulgaris).]