Cetacea

se-ta'she-a, warm-blooded, four-legged animals that have become fishlike in form. In some respects they resemble the seal and the walrus, but they have become still more degenerate through disuse of their legs on land. It is difficult to believe that a whale was originally a four-legged land animal suckling its young; but such, scientists tell us, is the case. The cetacea includes the various whalebone or baleen whales, the sperm whales, the dolphins, the porpoises, the so-called blackfish, the grampus, the killer, the herring hog, and the narwhal. See Whale; Porpoise, etc.