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base, osts) ; dermal rays of the dorsal and anal fins more numerous than their endo-skeletal supports. Heterocercal. Vertebrae acentrous. Families: Palaeoniscidae, Platysomidae, Catopteridae, Belonorhynchidae, Chondrosteidae, Polyodontidae, Acipenseridae. In the three first families (Devonian to See also:

Jura), the mouth is toothed, praemaxillary bones are present, and the maxillaries are large, the bones of the upper See also:

SURFACE

surface of the See also:

head are paired, branchiostegal rays are present, and the See also:

BODY

body is covered with rhomboidal, typically ganoid bony scales.

In the See also:

FOURTH

fourth See also:

FAMILY

family (Trias to See also:

LIAS

Lias), the snout is much elongate, and See also:

LONGITUDINAL

longitudinal See also:

SERIES (a Latin word from serere, to join)

series of scutes extend along the body, one on the back, one on the belly, and one on each side. The Liassic Chondrosteidae show an approach to the sturgeons, and See also:

FORM (Lat. forma)

form a sort of connecting See also:

LINK

link between them and the Palaeoniscidae. The mouth was edentulous, praemaxillary bones were absent, but the maxillary bone was well developed, though small; the membrane bones of the skull were paired; branchiostegal rays were present; scales were absent, except on the caudal See also:

LOBE

lobe. In the See also:

MODERN

modern Polyodontidae and Acipenseridae, whose first representatives appear in the See also:

EOCENE (Gr. *In, dawn, icauvos, recent)

Eocene, praemaxillaries are absent and the mouth is edentulous (Acipenseridae) or beset with See also:

minute See also:

TEETH (O.E. Eel); plural of tooth, O.E. top)

teeth (Polyodontidae), the membrane bones of the skull are more irregular and comprise azygous elements, branchiostegal rays are absent, and the body is naked or covered with small ossifications and longitudinal series of bony scutes, whilst the caudal fin is scaled exactly as in the Palaeoniscidae. Barbels are absent in the Polyodontidae. In the Polyodontidae, represented by one See also:

SPECIES

species, the See also:

PADDLE

paddle-See also:

fish or See also:

SPOON (O. Eng. span, a chip or splinter of wood, cf. Du. spoon, Ger. Spahn, in same sense, probably related to Gr. r4 v, wedge)

spoon-See also:

BILL

bill (Polyodon See also:

FOLIUM

folium), in the See also:

MISSISSIPPI

Mississippi, See also:

OHIO

Ohio and See also:

MISSOURI

Missouri See also:

rivers of See also:

North See also:

AMERICA

America, and by another (Psephurus gladius) in the Yang-tse-kiang and Hoang Ho rivers of See also:

CHINA

China, the snout is produced into a very See also:

long, spatulate (Polydon) or sub-conical (Psephurus) appendage, apparently useful in stirring up the mud of the thick See also:

WATERS, TERRITORIAL

waters in which these fishes live, and perhaps a tactile See also:

ORGAN

organ compensating the very reduced See also:

SIZE

size of the eyes. Psephurus gladius is said to grow to a length of 20 ft. The sturgeons (Acipenseridae) are divided into two genera: Acipenser, distributed over the coasts and fresh waters of the temperate parts of the See also:

NORTHERN

northern hemisphere, and Scaphirhynchus, inhabiting North America and Central See also:

ASIA

Asia. About twenty species of Acipenser and five of Scaphirhynchus are known. The sturgeons are of See also:

GREAT

great value for their flesh, their eggs (See also:

CAVIARE, or CAVIAR

caviare) and the See also:

ISINGLASS (probably a corruption of the Dutch huisenblas, Ger. Hausenblase, literally " sturgeon's bladder ")

isinglass from the air-bladder; several species are migratory, ascending rivers to spawn. The largest species attain a length of to to 18 ft. SUB-ORDER II.—HOLOSTEI Clavicle proper absent.

Ventral fins inserted more or less far back, without or with See also:

mere rudiments of endo-skeletal rays; dermal rays of the dorsal and anal fins corresponding to their endoskeletal supports. Caudal fin of an abbreviate-heterocercal or homocercal type. Families: Semionotidae, Macrosemiidae, Pycnodontidae, Eugnathidae, Pachycormidae, Lepidosteidae, Aspidorhynchidae, Amiidae. First appear in the See also:

PERMIAN

Permian with the Semionotidae, become abundant in the Trias, dominant in the See also:

JURASSIC

Jurassic, begin to decline in the Cretaceous, and from the Eocene to the present See also:

day are reduced to the two families Lepidosteidae and Amiidae, the modern representatives of which inhabit the fresh waters of North America. In most of the Holostei the scales are bony, rhombic and covered with an See also:

ENAMEL (formerly " amel," derived through the Fr. amail, emmll, esmail, from a Latin word smaltum, first found in a 9th-century life of Leo IV.)

enamel-like (ganoine) coating, but there is every gradation between this so-called ganoid type of scaling and the See also:

CYCLOID (from Gr. iciidws, circle, and ennos, form)

cycloid type exemplified by the Amiidae. Fulcra also disappear in some of the more specialized types. The mouth is always large and toothed, and branchiostegal rays are invariably present; a single gular See also:

PLATE

plate is often present. In the earlier See also:

groups the notochord was persistent, with or without See also:

ANNULAR, ANNULATE

annular centra, or with each centrum composed of two elements—pleurocentrum and hypocentrum; these elements remain distinct and alternate in the caudal region of the Amiidae, whilst in the Lepidosteidae the centra are as fully developed as in most Teleosteans, and opisthocoelous or convexo-See also:

CONCAVE

concave. The See also:

pike-like genus Lepidosteus was abundant in See also:

EUROPE

Europe in Eocene and See also:

MIOCENE

Miocene times, and is now represented by three species in eastern North America, See also:

Mexico and See also:

CUBA (the aboriginal name)

Cuba. The largest species reaches a length of to ft. Amia, the bowfin, of similar See also:

GEOLOGICAL

geological See also:

AGE (Fr. age, through late Lat. aetaticum, from aetas)

age, is a much smaller fish, not exceeding 2 ft., from the eastern parts of North America. Its air-bladder is cellular and acts as an See also:

ACCESSORY

accessory breathing organ.

It deposits its eggs in a sort of See also:

NEST

nest, which is protected by the male, who for some See also:

time accompanies the swarm of See also:

young See also:

fry and defends them with great courage. Leedsia problematica, one of the Pachycormidae from the See also:

Oxford See also:

clay, probably reached a length of 3o ft., and is the largest known Teleostome.

End of Article: ORDER II1

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