The history of the dolphin is one of the most fascinating and instructive in the historiography and the history of ideas in the western world. Indeed, it provides one of the most illuminating examples of what has probably occurred many times in human culture—a virtually complete loss of knowledge, at least in most segments of the culture, of what was formerly well understood by generations of men. “Not in entire forgetfulness” in some regions of the world, but certainly in “a sleep and a forgetting” in the most sophisticated centers of the western world. Dolphins are mammals. They belong in the order Cetacea, suborder Odontoceti, family Delphinidae. Within the Delphinidae there are some twenty-two genera and about fifty-five species. The count includes the Killer Whale, the False Killer Whale, the White Whale, and the Pilot Whale, all of which are true dolphins. There are two subfamilies, the Delphinapterinae, consisting of the two genera _Monodon monocerus_, the Narwhal, and _Delphinapterus leucas_, the White Whale or Beluga. These two genera are distinguished by the fact that none of the neck vertebrae are fused, whereas in all remaining genera, embraced in the subfamily Delphininae, at least the first and second neck vertebrae are fused. It was Aristotle in his _History of Animals_ (521b) who first classified whales, porpoises, and dolphins as Cetacea,τὰ κήτη οῖον δελφις καὶ φωκαὶνα καὶ φάλαινα. Aristotle’s account of the Cetacea was astonishingly accurately written, and quite evidently from firsthand knowledge of these animals. While most dolphins are inhabitants of the seas, there are some that live in rivers, and quite a few that are denizens of fresh-water rivers removed many miles from the sea. With one exception the diet of dolphins is principally fish. The one exception is _Sotalia teuszii_, which lives in the Kamerun River, and is believed to feed exclusively on vegetable matter. The Ting Ling dolphin (_Lipotes vexillifer_) lives in Ting Ling Lake, six hundred miles up the Yang-tse-Kiang. Another dolphin, the Susu or Ganges dolphin (_Platanista gangetica_) of Brahmapootra, the Ganges, and the Indus, has lenseless eyes and is almost blind. The fresh-water dolphins belong in the family Platanistidae. It is of interest to note that, in connection with the vegetable feeding habits of the Kamerun dolphin, Lycophron, in his _Alexandra_, makes his dolphins feed on trees, and Ovid, in the _Metamorphoses_ (III, 1, 202), describes a flood in which the dolphins take possession of the woods. Nonnus Panopolitanus, in the _Dionysiaca_ (VI, 265-266), also describes dolphins as feeding on trees.