Abstract

Part I. Aristotle proposed a method of defining an entity, e.g. an animal species, by successive subdivisions of the broader class ( genos) to which it belongs; if fully implemented, this would have resulted in a classification of animals. Definition of bird-species by subdivision of the class Birds would require the description of sub-classes intermediate between the major class and individual species. Examination of Aristotle's main discussions of birds shows that he had no complete system of such sub-classes, but four groups of bird species are repeatedly mentioned and are described in some detail: Hook-taloned birds, terrestrial birds which fly weakly (i.e. Gallinaceous birds), web-footed birds, and fissipede waterside birds. Aristotle must have thought of these groups as, at least, likely to be usable in the definition of bird-species, but made little progress towards formulating such definitions. Part II. Pliny offers a hint of a different approach to avian classification; but in the sixteenth and seventeenth centuries Edward Wotton, Belon, Gesner and Aldrovandi were most strongly influenced by Aristotle, and so, to a much lesser extent, were Willughby and Ray. Linnaeus and Yarrell are examples of eighteenth and nineteenth century authors who still made use in their classifications of the four groups, of hook-taloned birds etc., described in Part 1.