Aristotle's "De Animalibus" has been an important source of zoological knowledge both for the ancient Greeks and for the medieval Arabs and Europeans. The work has twice been translated into Latin, once direct from the Greek by William Moerbeke and once by Michael Scot from an existing Arabic translation. Of these, Scot's translation is the oldest. The "De Animalibus" is composed of three sections: "History of Animals" (10 books), "Parts of Animals" (4 books) and "Generation of animals" (5 books). The present volume contains a critical edition of "Parts of Animals".