. Animal physiology. Physiology, Comparative; Physiology, Comparative. 82 GENERAL CHARACTERS OF FISHES. the form of a still more remarkable animal, the Lepidosiren, recently brought from the rivers of Africa, the metamorphosis of which appears to be checked at a still earlier period, so that it is very difficult to decide whether it should be regarded as a fish or a reptile, so complete is the mixture of characters which it presents. 98. The class of Fishes is distinguished from all other Ver- tebrata, by the adaptation of the animals composing it, to breathe by means of water in their adult s
. Animal physiology. Physiology, Comparative; Physiology, Comparative. 82 GENERAL CHARACTERS OF FISHES. the form of a still more remarkable animal, the Lepidosiren, recently brought from the rivers of Africa, the metamorphosis of which appears to be checked at a still earlier period, so that it is very difficult to decide whether it should be regarded as a fish or a reptile, so complete is the mixture of characters which it presents. 98. The class of Fishes is distinguished from all other Ver- tebrata, by the adaptation of the animals composing it, to breathe by means of water in their adult state, so as to be capable of living in that element only. Like Reptiles, they are oviparous and cold-blooded ; and in these characters they differ completely from the whales and other Mammalia, which are, like them, inhabitants of the great deep, but which are warm-blooded, viviparous, and air-breathing animals. There is a simple external character by which the members of the two classes may be at once distinguished. The animals of the whale tribe are, like fishes, chiefly propelled through the water by means of a flattened tail; but in the former the tail is flattened horizontally, so that its downward stroke may serve to bring the animal to the surface to breathe; whilst in the latter it is flattened verti- cally, that its strokes from side to side may simply propel the fish through the water. This flattening or compression of the body is seen more or less in almost all fishes; and it is inti-. Fig. 38.—Skeleton of the Perch. mately connected with the nature of their motion through the element they inhabit, as it serves the double purpose of dimi-. 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 Carpenter, William Benjamin, 1813-1885. London : Wm. S. Orr and Co.
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