Bony Fishes

Bony Fishes, a book-name for the Teleostei, the largest and most important sub-class of Fishes (q.v.). They appear first in the chalk, and, according to Dr. Gunther, stand in the same relation to the Palaeichthyes (q.v.) as placental mammals do to the marsupials. The chief characteristics of this subclass are: A more or less complete bony skeleton. the centra of the vertebrae being always ossified, and some portion of the cartilage of the skull replaced by bone; the optic nerves cross; the gills are free and covered by an operculum (q.v.); the branchial artery has a non-contractile dilatation in front of the heart; there is no spiral valve attached to the intestines. The Teleostei are divided into six orders: -

1. Acanthopterygii. - Spinous rays on dorsals, and ventrals; lower pharyngeals separate; air-bladder without duct. (Examples: mackerel, mullet, perch, sea-bream.)

2. Acanthopterygii Pharyngognathi. - Tliese ditfer from No. 1 in having the lower pharyngeals united. (Examples: goldsinny, tautog, wrasse.)

3. Anacanthini. - Fins without spinous rays; ventrals, if present, on throat or breast, lower pharyngeals separate; air-bladder without duct. (Examples: cod, haddock, hake, ling, sole, turbot.)

4. Physostomi. - Fins without spinous rays; ventrals on belly; air-bladder with duct. (Examples: carp, pike, roach, salmon.)

5. Lophobranchii. - Gills composed of small rounded lobes; dermal skeleton of numerous pieces. (Examples: hippocampus, pipe-fish.)

6. Plectognathi. - A soft dorsal opposite the anal; ventrals obsolete or reduced to spines; skin armed with scutes or spines, or naked. (Examples: file-lish, globe-fish.)