Linnaeus' Systema Naturae (the Tenth Edition) is the starting point for the modern, binomial system of animal nomenclature; no names published before that have any standing. Consequently, for any taxonomic reappraisal and revision it is essential that it is clear what Linnaeus was referring to in his Systema Naturae. Although in the majority of cases the sources and references used are clear and can easily he deciphered, the remainder are difficult and obscure, causing confusion and making it difficult to reach definitive conclusions on nomenclatural problems. By providing this key to the sources used by Linnaeus, Professor Heller has both clarified problems with Systema Naturae and provided taxonomists with an authoritative tool to facilitate their work.
Professor Heller, the author of this work, was Professor and Chair of Classics at the University of Minnesota and then a professor and head of the classics department at the University of Illinois and after his retirement in 1975 became Emeritus Professor. This background in the classics led him to take an active interest in the works of Linnaeus and the sources used by Linnaeus. Although he had published papers related to the classical sources used by Linnaeus, his work to provide a key to the sources used by Linnaeus remained in manuscript form. Despite this work being at an advanced stage, his death in 1985 prevented its completion. Mr Wheeler, Head of the Fish Section of the Natural History Museum., London, subsequently took over Professor Heller's work, but ill health prevented him completing it. However, Professor Penhallurick independently rediscovered Professor Heller's work and by acting as editor has been able to bring it to completion and publication.
Professor Penhallurick, the editor of this work, after an undergraduate degree in English received his doctorate in linguistics and until his retirement has had a career in communication at the University of Canberra. He is a very keen and active ornithologist and his ambition is to produce a complete checklist and synonymy for every generic, subgeneric, specific and subspecific bird name. His knowledge of Latin, a result of receiving a traditional education, has meant he has been able to actively research original sources used in bird taxonomy. This led him to the sources used in Linnaeus' Systema Naturae (and to other early authorities) and from that to his discovery of Professor Heller's unpublished manuscript and notes on Linnaeus' Zoology. By editing this work Professor Penhallurick has made available to taxonomists Professor Heller's valuable key to the sources used by Linnaeus.