. Elements of zoölogy. Zoology. i56 BACKBONED ANIMALS. distinct types : heterocercal, in which the lobes are un- equal, as in the shark (Fig. 198), and homocercal, where they are equal, as in the perch (Fig. 193). Digestion.—The teeth that rudely prepare the food for digestion are loosely attached to the bones of tha. Fig. 194.—Internal structure of the minnow, ribs removed, and the living fish. A, «, nose-pit; e, eye-nerve; ea, ear-nerve ; g, gills; //, heart; t, food-tube; j-, stomach ; k, kidney; v, vent; d a, dorsal artery; a, air- bladder ; £, backbone ; n v, nerve-cord or spinal cord. B,
. Elements of zoölogy. Zoology. i56 BACKBONED ANIMALS. distinct types : heterocercal, in which the lobes are un- equal, as in the shark (Fig. 198), and homocercal, where they are equal, as in the perch (Fig. 193). Digestion.—The teeth that rudely prepare the food for digestion are loosely attached to the bones of tha. Fig. 194.—Internal structure of the minnow, ribs removed, and the living fish. A, «, nose-pit; e, eye-nerve; ea, ear-nerve ; g, gills; //, heart; t, food-tube; j-, stomach ; k, kidney; v, vent; d a, dorsal artery; a, air- bladder ; £, backbone ; n v, nerve-cord or spinal cord. B, «, nose; gc, gill-cover ; a/, arm-fin ; //, leg-fins ; s /, single fins ; m j, mucous scales. mouth, and even the tongue, not being confined to the jaws alone. Food passes into the food-tube (Fig. 194, /), and thence into the stomach, s, the rejected portions being expelled at v. The liver is generally large. The position of the kidneys is shown in Fig. 194, k. Circulation.—The heart (Fig. 194,/*), as a rule, consists. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Holder, Charles Frederick, 1851-1915; Holder, Joseph Bassett, 1824-1888, joint author. New York : D. Appleton and company
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
