This true son of the water, gliding and mobile as his mother, glides by means of his mucus, cleaves with his head, impelled by his contractile muscles, and finally, with his strong fins rows and steers. The least of these powers would suffice, but he unites them all; a perfect model and absolute type of swift motion. Even the bird is less mobile, seeing that he has to perch. He is fixed for the night, but the fish, never; even asleep, he still floats. So extremely mobile, he at the same time is in the highest degree strong and lively. Wherever there is water, there is the fish: he is the universal creature of the globe. In the loftiest lakes of Asia and of the Cordilleras, where the atmosphere is so rarefied that no other creature can endure it, the fish lives and thrives. It is the red fish of the Gudgeon species, which thus looks down upon all the earth. In like manner, in the great depths, beneath the most enormous weights, live the Herring and the Cod. Forbes, who divides them into ten superposed beds or stages, finds them all inhabited, and in the lowest of all, supposed to be so dark, he finds a fish provided with eyes so admirable that he finds sufficient light in that which seems to us the uttermost darkness of night. There is yet another privilege of the fish. Many species, as Salmon, Shad, Eels, Sturgeon, &c., can live equally in fresh water or sea water, and regularly migrate from one to the other. Many families of fish include both sea fish and fresh water fish, as for instance, the Thornback. Nevertheless, peculiar degrees of heat, peculiar food, and peculiar habits, seem to confine them within certain limits in the seas, free as that element is. The warm seas are as a confining wall beyond which the polar species cannot pass; and on the other hand, the fish of the warm seas are stopped by the cold currents at the Cape of Good Hope. We know of only two or three species that can be properly called cosmopolitan. Few of them frequent the open sea; most of them hug the shore, and have favorite shores to frequent. Those of the United States are not those of Europe. Then, too, fish have peculiarities of taste which attach them to certain localities, though they do not actually confine them there. The Thornback grovels in the mud, Soles in sandy bottoms, the Bullhead loves the high bottoms, and the Sea Eel the rocks. The Scorpene, or flying fish, swims and flies by turns; when pursued by fish, she darts from the water, and for some distance sustains herself in the air; and when pursued by birds she drops back into the water.