SHARK, Squalvs, a Linnuean genus of cartilaginous fishes, now forming in Anther's system a suborder of plagiostami (q.v.). and divided into a number of families and many genera. The sharks have generally an elongated form, tapering gradually to the taiLt and not much thickened in the middle. The muzzle projects over the mouth; the nostrils are situated on the under-side of the muzzle. The males have elaspers. The gill-openings are lateral. There is no cartilage between the snout and the pectoral tin; as in the rays. Some of the sharks are ovoviviparous; others lay eggs, generally a pair at a time, more being produced in succession. The eggs are large in comparison with those of osseous fishes, and are of a square or oblong form, with a tough horny coat, each corner prolonged into a tendril, the tendrils being apparently of use for their evanglement among sea-weeds. These eggs, or at least their empty cases, are very freqamtly cast up by the waves on the sea-beach, and are popularly known as sea purses or mermaids' purses. Near the head of the inclosed embryo there is a slit in the, case through which water enters for respiration, and there is another at the opposite end, by which it is discharged. The young fish ruptures the case at the head, where it is weaker than at any other part, and on issuing from it, carries a yolk attached to its belly for its nourishment. until it is able to seek food. At this stage of its existence, its respiration is also aided by filaments projecting from the gills through the gill-openings, which are absorbed as it grows older. The teeth are generally large, sharp, and formed for cutting, with the edge often serrated; but in the genus cestraeton (q.v.) the teeth are pavement-like; and in some genera they are small and numerous. The angel-fish (q.v.l is ranked among the sharks, but differs from the rest in its flattened form. Some of the smaller sharks are popularly known by the names dogfish, hound, tope, etc. In the articles Cestracion, Dogfish, Fox Shark, Hammer-head, and Tope, sonic of the shark tribe are noticed. It only remains here to notice a few of the more interesting of thoSe which do not come under any of these heads.
The SHARK, Carchurius vulgaris, is the most dreaded of all the monsters of the deep. The family carcharidce, to which it belongs, have two dorsal fins, the first dorsal-placed over the space between the pectoral and ventral fins; they have a nicti tating 'membrane; and have no spout-holes. In the genus carcharlas the snout is flattened. ' The white shark attains a great size; one has been caught of 37 ft. in length. The body is covered with a hard skin, and is grayish-brown above and whitish below. It is a very rare visitant of the British coasts, if indeed another -species has not been mistaken for it; but is found in the Mediterranean. and is plentiful in the seas of many
of the warmer parts of the world, often following ships to feed on any animal substance that may be thrown or may fall overboard, and' often in its indiscriminate voracity swallowing things which are indigestible. A lady's work-box has been found in a shark's stomach; and the papers of a slave-ship, which had bean thrown overboard, in that of another. Human beings are not 'infrequently its prey, and a large shark is not only capable of biting off the limb of a man. but of snapping the body in two, and has even been known to swallow a man entire. Its head is large, the mouth large and wide; furnished with a terrible apparatus of teeth, of which there are six rows in the upper jaw and four in the lower; the teeth are triangular, sometimes 2 in. in breadth, sharp edged, and serrated; when not in use they are laid back in the mouth, nearly flat, but when the shark bites they are brought up—or at least those of the outer rows—by atoms of muscles with which each tooth is independently provided. The tail, as in all the sharks, is beterocercal, but its lobes are more nearly equal than in most of them. The shark is often captured by sailors, by means of a great hook baited with a piece of meat, and attached to a chain, as the shark's teeth readily bite through any rope. When the shark is hooked and hauled on board. great care is requisite to avoid danger both from the mouth and from the tail, the powerful action of the latter being generally interrupted by a sailor springing forward and cutting it above the fin with a hatchet. A curious method of catching the shark is practiced in the South Sea Islands; a log of wood is set afloat with a strong rope attached to it, at the end of which is.a noose, and the sheiks gathering about it as if from curiosity, one of them may be expected soon to get its head into the noose. and is at last wearied out by the log. Formidable as the shark is, !mu have sometimes successfully braved it in its own element, watching its turning— as from the position of its mouth it must do—to seize its prey, and stabbing it in the belly The BLUE SHARK, Carcharias glaucus, is much smaller than the white shark, seldom exceeding 8 ft. in length. It is also of a-more slender form. The upper parts are of a blue color, the belly white. This species is common in the Mediterranean and in the warmer parts of the Atlantic. It is not unfrequent on the south-western coasts of England in summer, apparently coming in pursuit of pilchards, and often doing great mischief to the nets and lines of fishermen, its sharp teeth biting through a net or line with the utmost ease.