TELEOSTEI, the order of bony fishes, corresponding very nearly with Cuvier's division of osseous fishes, and comprising nearly all the common fishes. The skeleton, instead of remaining throughout life nearly or quite cartilaginous, is nearly or com pletely ossified. The notochord is not persistent, as in the inferior orders; there is a well developed vertebral column, although it is sometimes more or less cartilaginous. The bodies of the vertebra' are araphiccelcrus or concave at both ends, forming a double conical, or globular cavity which is filled with the cartilaginous or semi-gelatinous remains of the notochord, which confers great flexibility on the vertebra] column. The ossification is not carried further, except in the bony pike, a ganoid. The skull is much complicated, being composed of a great number of distinct cranial bones, and a lower jaw, or mandible, is always present. The pectoral arch has a clavicle, and the paired fins, when present, are supported by rays. Those having soft rays are called nudacop terygii; those having spinous rays are called acanthopterygii. Besides the paired tins there is a variable number of unpaired integumentary expansions known as median fins, which when fully developed consist of one, two, or three fins on the back, called dorsal fins, one at the posterior end, called the caudal fin, and one or two on the ventral sur face, called anal fins. The spines of the caudal fin are set vertically, and not horizon tally, as in cetacea, and in all the bony fishes the form is said to be homocercal, that is, consisting of two equal lobes, but this is not strictly true, as the tail is generally not quite symmetrical, although not so manifestly unsymmetrical as in the cartilaginous fishes, sharks, and rays. Tha median fins are always supported by joints upon a series of interspinous bones whose spines pass inward and are attached to the spinous pro cesses of the vertebrw. The heart contains two chambers, an auricle and a ventricle, and the branchial artery has its base developed into a bulbus arteriosus, which, however, has no striated muscular fibers, is not rhythmically contractile, and is only separated from the ventricle by a single row of valves. The respiratory organs are in the form of
free, pectinated, or tufted branchim, situated in two branchial chambers, each of which communicates internally with the pharynx by a series of clefts, and opens externally by a single aperture or gill-slit, protected by a bony gill-cover, beneath which there is a branchiostegal membrane, supported upon branehiostegal rays. The branclike are sup ported by a series of bony arches, usually five on each side (the anterior four only bear ing gills), which are connected below with the hyoid bone, and above with the skull. The nasal sacs never communicate posteriorly with the pharynx. These fishes are gen erally covered with horny clycoid or etenoid scales overlapping each other, and forming what is called an exoskeleton,but these scales are sometimes absent,or represented by plates of true bone, which are sometimes ganoid, that is composed of an inferior layer of true bone covered by a superior layer of polished enamel; and sometimes formed of shagreen like bony spines. The stomach is capacious; pyloric eca are present. An air-bladder may or may not be present, and may or may not communicate with the gullet. The subdivisions of the osseous fishes are numerous, and comprise a great number of fami lies which cannot be enumerated here.
The suborder malacopteri, or soft-rayed division. always have an air, or swim-blad der, which communicates with the ces3pliagus by a duet which is regarded as homolo gous to the wind-pipe of air-breathing animals having lungs. The skin is sometimes naked, but is usually covered with cycloid scales, sometimes with ganoid plates. The rrutlacopteri arc into two groups, the apoda which have no ventral fins, and con tain the eel (q.v.) including the gymnotus (q.v.); and the abdominalia, having ventral fins, containing the pikes (q.v.) of the esociche (q.v.). ; the carp (q.v.), chub (q.v.), roach (q.v), minnow (q.v.), of the family of cyprinitha (q.v.); the various species of salmon and trout (q.v.) of the salmonidce (q.v).