Sturgeon, the name of cartilaginous fishes of the class of ganoids and family sturionidae. The body is elongated and fusiform, covered with a rough skin protected by five longitudinal rows of tubercular plates; the largest of these rows is along the back, and there is also one on each side, and one from each pectoral to the ventral fins; the plates are flattened, and marked with radiating striae. The head is depressed, and ends in a long triangular snout covered with bony plates; mouth funnel-shaped and protrusible, on the under surface, without teeth, having in front a few depending barbels, evidently organs of touch; gill covers very large and gills free; pseudo-branchiae and spiracles are present, but no bran-chiostegal rays; fins well developed, the dorsal and anal opposite and behind the ventrals; tail heterocercal or unsymmetrical, the vertebral cord being prolonged into the upper lobe as in the sharks, and strengthened by fulcra along its upper margin; a soft caudal on the under surface of the tail. The vertebral column consists of an undivided soft chorda dorsalis; the air bladder is very large, communicating freely with the oesophagus; there is a spiral valve in the intestine, and a conglomerate pancreas.

They are generally large, and inhabit the northern temperate seas of both coasts of America, eastern Europe, and western Asia, from which they ascend the rivers in spring to spawn, returning to the salt water in autumn; species are also found in the great American fresh-water lakes, which never descend to the sea. They are oviparous; the food consists of any soft substances which they stir up from the bottom with their snouts, and of small fish; they frequently jump out of water. - The genus acipenser (Linn.) has the characters of the family. The common sturgeon of Europe (A. sturio, Linn.) attains a length of 6 to 10 ft., and sometimes more; it is found in the Caspian and Black seas and the rivers opening into them, and sometimes on the coasts of Great Britain and the Baltic; the flesh is delicate, and is largely consumed in Russia, fresh, salted, and pickled. A larger species, also found in the seas and rivers of S. E. Europe, is the beluga (A. huso, Linn.), attaining a length of 12 to 15 ft. and a weight of 1,200 lbs., and occasionally much larger; it ascends the rivers opening into the Caspian and Black seas, with other and smaller species.

The flesh is tough; the sound or air bladder furnishes an abundant supply of isinglass, for which great numbers are caught in Russia. Caviare is also made from the roe of the female, which sometimes constitutes one third of the weight of the fish; the skin is used for harness leather, and the dorsal cord, cut in pieces and dried, is used as food. The sterlet (A. Ruthenus, Linn.), found in the Caspian, and growing to a length of 2 or 3 ft., furnishes a most delicate food and the best caviare. In the Volga it spawns early in May, on rocky bottoms, in water of 54° F.; the eggs, which are easily fecundated artificially, soon adhere to any object; they are hatched in about seven days, the embryos being then about a quarter of an inch long; in ten weeks these attain a length of two inches, feeding on larva) of insects on the bottom. Both eggs and young will safely bear a journey of five days, and have been carried to W. Russia, and even to stock British rivers; the young live only in fresh water. The color in these species is brown of various shades, the plates whitish, and the abdomen silvery.

The several species in the Baltic hybridize freely, and are probaby only varieties of one. - In North America sturgeons are not found north of the watersheds between lat. 53° and 54° N., where the mean annual temperature is about 33° F.; they seldom enter clear cold streams, but ascend muddy rivers in such numbers that many largo Indian tribes subsist entirely on their flesh in summer; each watershed has its own species, varying in some minor characteristics. The sharp-nosed sturgeon (A. oxyrhynchus, Mitch.) attains a length of from 3 to 7 ft.; it is found on the coasts of New England, New Brunswick, and Nova Scotia; it is common in Long Island sound from the middle of June to October, and is taken by harpoon and in nets; the smaller specimens are esteemed for the table; it is grayish brown above, silvery on the sides, and white below. The short-nosed sturgeon (A. brevirostris, Mitch.) is dusky above and white below; the snout is short and blunt; it attains a length of 2 to 5 ft., and is so common in the Hudson that its flesh in the market has been known as Albany beef; it much resembles the A. sturio of Europe. Other species are described from the northern waters, the rivers of the N. W. coast, and from Lake Superior, by Richardson and Agassiz. - The genus polyodon (Lac6p.) or spatularia (Shaw) has the general form of acipenser, but is without the bony plates on the body and head; the snout is very much elongated, and compressed into a thin leaf-like organ, partly bony and partly cutaneous, sometimes nearly as long as the body; gill covers very large, extending far back in a membranous point; the mouth is wide, with numerous minute teeth in the young animal, which are lost with age.

The spoon-bill sturgeon (P. folium, Lacep.) is steel-blue above and white below; it attains a length of 5 ft., and is found in the Mississippi, Ohio, and their tributaries; it is also called shovel fish and paddle fish; the flesh is tough; the singularly shaped snout is used to shovel up the mud in search of food. The genus plati-rostra (Les.) is probably only the adult of polyodon, the principal difference being the absence of teeth.

Common European Sturgeon (Acipenser sturio).

Common European Sturgeon (Acipenser sturio).

Sharp nosed Sturgeon (Acipenser oxyrhynchus).

Sharp-nosed Sturgeon (Acipenser oxyrhynchus).