Shark
2 of the 7 encyclopedias on this shelf carry an entry for Shark. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a voracious fish of the deep sea. Sharks in an arm of the sea are as active, as destructive, and ever-hungry as pickerel in a small pond. The common man-eating or white shark of the Mediterranean and other warm waters attains a length of fifteen to twenty feet, and in extreme cases over thirty feet. Its snout projects over its mouth. Its jaws are fitted with formidable, triangular teeth two inches long. The two jaws close together like immense saws. The teeth of one fit the depressions of the other, and not only that, but there are six rows in the upper jaw and four in the lower. The shark has a full set of fins and a forked tail. It will follow a ship for days for the sake of the offal thrown overboard. Sharks are exceedingly dangerous in certain waters. A man lost overboard or caught swimming is likely to be cut in two by a single snap of those ponderous saw-like jaws before help can reach him. Sailing ships lying becalmed or moving slowly in tropical waters offer opportunity for fine sport,--shark fishing. A large hook is baited with a piece of meat and thrown out astern with a chain for a fishing line, for the shark would cut the strongest cable. If the shark bites he is hauled aboard with a capstan and is chopped into pieces. Sailors insist that a "man-eating" shark is accompanied by a mackerel-like "pilot" fish, sometimes by several, who aim to keep him from harm and are distressed when he comes to grief. The shark family is a large one. There are 150 species. Most of them are from two to eight feet long and are harmless. The Greenland shark attacks whales. A host of dogfishes--small sharks--pursue the shoals of mackerel and other food fishes. The hammer-head is a natural curiosity. The cheeks are extended enormously, giving the head the shape of a carpenter's wooden mallet. The two eyes are in the ends or hammer faces of the mallet, twenty inches apart. The hide of the shark is without scales but it is covered with flinty points. It makes an excellent substitute for sandpaper.
Collier's New Encyclopedia (1921)
an English popular name for any individual of the group Selachoidei. The body is generally elongated; the muzzle, on the under side of which the nostrils are placed, projects over the BLUE SHARK mouth, and the males have claspers (with the function of intermittent organs) attached to the ventral fins. The ova are large and few in number, impregnated, and in some genera developed, within an uterine cavity; in others deposited in a tough, horny case, from which the young fish, carrying a yolk-bag, for its nourishment till it is able to seek food, is discharged; in this stage the gill-laminæ are prolonged into filaments projecting beyond the gill-cavities, but these are soon absorbed. The teeth are generally large, sharp, and formed for cutting, often with serrated edges, but in some genera they form a solid pavement-like mass. Sharks are scaleless, and the skin is usually very rough (see SHAGREEN). They are most numerous in tropical seas. The larger sharks are exclusively carnivorous, and some of them extremely dangerous to The smaller sharks are popularly man. known as dog fishes or hounds, and do great damage to fishermen's lines and nets. The flesh of sharks is coarse, but it is sometimes eaten; the Chinese use sharks' fins for making thick gelatinous soups, and the liver yields an oil. The rough skin is employed by joiners to polish fine-grained wood, and by cutlers to cover the hilts of swords to make them firmer in the grasp. Figurately, a greedy, artful fellow; one who fills his pocket by sly tricks.