Among several manuscripts left behind by Swedish naturalist Peter Artedi following his untimely death in 1735 is an unfinished effort to classify the mammals, or the 'hairy animals', as Artedi called them. Titled 'Idea institutionum Trichozoologiae' ('An outline of the principles of the science of hairy animals'), it presents a four-tier hierarchy composed of orders, sections ('sectio'), genera and species, that foretells the work of Carl Linnaeus. An analysis of the impact that Artedi's account might have had on Linnaeus's treatment of the mammals in the various editions of his Systema naturae is presented. Results show that both authors owed much to the earlier work of English naturalist John Ray, with precedent going back to Aristotle.