Although Linnaeus sought to lay down guidelines in Philosophica Botanica, 1751, there were no generally accepted rules governing the formation, use, and priorities of names in zoology for nearly one hundred years afterwards. Many authors embraced Linnaeus’s simple binominal system, but chose to do so in an undisciplined fashion. Naturalists such as François Levaillant and the Comte de Buffon did not recognise the order heralded by the Swedish botanist, but their works were eagerly scanned and used as bases for catalogues and nomenclators by subsequent cabinet authors. The names of Levaillant, de Buffon, and de Azara will not be found amongst the ranks of Linnaean descriptive authors, but their works are vital sources for the etymologist.
As the number of new species swelled to a flood, the Linnaean binominal system was threatened with collapse as authors independently described the same species under different names, unaware of, or perhaps without regard for, the works of others. Often males, females, immatures and colour morphs of the same species were described as different species. Moreover, authors differed in their approaches to the Linnaean nomenclatural system, disagreeing as to whether inappropriate names, original mis-spellings, barbarisms (from non-classical languages), and so on, should be corrected and changed or allowed to stand. As species became better known, the earlier errors were gradually sorted out and amended. The result, however, was a plethora of names, disagreement on availability and usage of names for individual species, and differences on the starting date for binominal nomenclature (whether it should be pre-Linnaean, Linnaeus’s tenth edition of 1758, or Linnaeus’s twelfth edition of 1766). Great instability in the use of names and a collapse of binominal nomenclature loomed less than 100 years after Linnaeus introduced his concept of an efficient international system of biological names essential for communication between all biologists.
The most successful of the early attempts to bring uniformity to zoological nomenclature was the Strickland Code, conceived by the British zoologist Hugh Strickland and presented to the British Association for the Advancement of Science in 1842. It was widely adopted by the scientific community, and became the basis of subsequent codes, including the American Ornithologists’ Union Code and eventually the Règles Internationales. The Strickland Code adopted the twelfth (1766) edition of the Systema Naturae as the starting date for zoological nomenclature, a decision broadly accepted at the time in Britain and parts of continental Europe. However, many workers in North America and Europe argued that the tenth (1758) edition of Linnaeus should be so used. This was enshrined by the American Ornithologists’ Union in 1886, and was enthusiastically embraced by most workers except the British, who remained isolated until 1901. In that year the Fifth International Congress of Zoology at Berlin adopted the tenth edition of Systema Naturae and promulgated the first set of rules of zoological nomenclature to be recognized internationally, the Règles Internationales de la Nomenclature Zoologique (published in 1905). These rules have been modified and clarified over the years, and underwent a major revision in the 1950s, resulting in publication of the new International Code of Zoological Nomenclature (ICZN) in 1961 (4th edition, 1999).
“The objects of the Code are to promote stability and universality in the scientific names of animals and to ensure that the name of each taxon is unique and distinct” (ICZN (1999), 4th ed.). To those ends the three basic principles of priority, preservation of well-established names, and homonymy, are key to understanding the usage of scientific names in the literature and explained on this site.