David Balme's long-awaited major critical edition of Aristotle's largest and perhaps least studied treatise is based on a collation of the 26 known extant manuscripts and a study of the early Latin translations. Begun in 1975, with his work towards the Loeb editio minor of books VIIX, this edition of all ten books, including a very full apparatus criticus, was largely complete by 1989 when Professor Balme died, but it needed extensive work to put it in publishable form. This work has been carried out by Allan Gotthelf, Balme's friend and associate. Volume I of the edition contains the complete text of the Historia Animalium, the critical apparatus, and Balme's introduction to the manuscripts, expanded and updated with the assistance of Friederike Berger, and in consultation with the editors of forthcoming editions of the extant medieval translations. A substantial index to the text has been provided by Liliane Bodson in collaboration with Professor Gotthelf.