. A manual of zoology. Zoology. 574 CHORD AT A. cycloid scales. The living forms (the group appears in the trias) have ossi- fied opisthoccelous vertebrae and diphy- or homocercal tails. Lepidosteid^. Scales rhomboid, branchiostegal rays present, apseudo- )>ranch,but no spiracle. Xe^^g^w,* garpike. Amiid^, distinctly teleos- tean in appearance with cycloid scales, amphico5lous vertebrae, and heart with reduced conus (fig. 596, B). Amia* bow fin. Sub Glass III. Teleostei. The teleosts owe their name to the extensive ossification of the skeleton, which consists, in the trunk, of amplii
. A manual of zoology. Zoology. 574 CHORD AT A. cycloid scales. The living forms (the group appears in the trias) have ossi- fied opisthoccelous vertebrae and diphy- or homocercal tails. Lepidosteid^. Scales rhomboid, branchiostegal rays present, apseudo- )>ranch,but no spiracle. Xe^^g^w,* garpike. Amiid^, distinctly teleos- tean in appearance with cycloid scales, amphico5lous vertebrae, and heart with reduced conus (fig. 596, B). Amia* bow fin. Sub Glass III. Teleostei. The teleosts owe their name to the extensive ossification of the skeleton, which consists, in the trunk, of ampliicodlous vertebrae, and ill front a skull with numerous primary and secondary bones, already enumerated (p. 500, fig. .589). Maxillaries and premaxil- laries are present, but these are frequently without teeth, since other bones of the mouth (vomers, palatines, liyoid, gill arches, su|)erior pharyngeals—the latter alone in Cyprinoids) may bear teeth. Frequently there are present small bones, usually forked, lying in the intermuscular septa above the ribs, which are not pre- formed in cartilage. These are the epipleurals, and are distinct from the ribs. In the fins both cartilage and dermal rays are ossi- fied, the former remaining small, the rays forming most of the support. These rays may either be soft and fiexible (Malacopteri) or hard and spine-like (Acanthopteri), a matter of elassificatory value. In the first case they consist of numerous small threads. Fio. 603.—Peifd (From Ludwig-Lpunis.) A, aual fin ; B, veutral fln: Br, pectoral fln , A', operculum; X. nc^strils ; E,. Kj, spiuous and soft dorsal flns ; S, caudal fln ; SI, lateral line. (fig. 002, IJr, A, B, R,X in the other the parts of a ray are fused to a spine which, sometimes provided with poison glands (Scorpceiia, AiiipJuican/he, etc.), become good defensive weapons. The tail is usually homocercal; the diphyecrcy of eels and other fishes is sec- ondary. The dermal skeleton consists of ctenoid or
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