Fishes . FiG. 18.—Jaws of a Parrot-fish, Sparisoma aurofrenutum(Val.). Cuba. found in the same fish. The Dissection of the Fish lived, and some may be even annual, dying after spawning, per-haps at the end of the first season. Teeth are wholly absent in several groups of fishes. Theyare, however, usually present on the premaxillary, dentary, andpharyngeal bones. In the higher forms, the vomer, palatines,and gill-rakers are rarely without teeth, and in many cases thepterygoids, sphenoids, and the bones of the tongue are similarlyarmed. Xo salivary glands or palatine velum are developed in fishe
Fishes . FiG. 18.—Jaws of a Parrot-fish, Sparisoma aurofrenutum(Val.). Cuba. found in the same fish. The Dissection of the Fish lived, and some may be even annual, dying after spawning, per-haps at the end of the first season. Teeth are wholly absent in several groups of fishes. Theyare, however, usually present on the premaxillary, dentary, andpharyngeal bones. In the higher forms, the vomer, palatines,and gill-rakers are rarely without teeth, and in many cases thepterygoids, sphenoids, and the bones of the tongue are similarlyarmed. Xo salivary glands or palatine velum are developed in tongue is always bony or gristly and immovable. Some-times taste-buds are developed on it, and sometimes these arefound on the barbels outside the mouth. The Alimentary Canal.—The mouth-cavity opens through thepharynx between the upper and lower pharyngeal bones into the. Fig. 19.—Sheepshead (with incisor teeth), Archnnargus probatocephaliis (Wal-bauin). Beaufort, X. C. oesophagus, whence the food passes into the stomach. The intes-tinal tract is in general divided into four portions—oesophagus,stomach, small and large intestines. But these divisions of theintestines are not always recognizable, and in the very lowestforms, as in the lancelet, the stomach is a simple straight tubewithout subdivision. In the lampreys there is a distinction only of the oesoph-agus with many longitudinal folds and the intestine with but The Dissection of the Fish 31 one. In the bony fishes the stomach is an enlarged area, eithersiphon-shaped, with an opening at either end, or else forminga blind sac with the openings for entrance (cardiac) and exit(pyloric) close together at the anterior end. In the variouskinds of mollets (Mngil) and in the hickory shad {Dorosoma),fishes which feed on minute vegetation mixed with mud, thestomach becomes enlarged to a muscular gizzard
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