A short history of nearly everything - Bill Bryson [180]
Over the years many of these were quietly dropped (though not all: the common slipper limpet still answers on formal occasions to Crepidula fornicata) and many other refinements introduced as the needs of the natural sciences grew more specialized. In particular the system was bolstered by the gradual introduction of additional hierarchies. Genus (plural genera) and species had been employed by naturalists for over a hundred years before Linnaeus, and order, class, and family in their biological senses all came into use in the 1750s and 1760s. But phylum wasn't coined until 1876 (by the German Ernst Haeckel), and family and order were treated as interchangeable until early in the twentieth century. For a time zoologists used family where botanists placed order, to the occasional confusion of nearly everyone.*36
Linnaeus had divided the animal world into six categories: mammals, reptiles, birds, fishes, insects, and “vermes,” or worms, for everything that didn't fit into the first five. From the outset it was evident that putting lobsters and shrimp into the same category as worms was unsatisfactory, and various new categories such as Mollusca and Crustacea were created. Unfortunately these new classifications were not uniformly applied from nation to nation. In an attempt to reestablish order, the British in 1842 proclaimed a new set of rules called the Stricklandian Code, but the French saw this as highhanded, and the Société Zoologique countered with its own conflicting code. Meanwhile, the American Ornithological Society, for obscure reasons, decided to use the 1758 edition of Systema Naturae as the basis for all its naming, rather than the 1766 edition used elsewhere, which meant that many American birds spent the nineteenth century logged in different genera from their avian cousins in Europe. Not until 1902, at an early meeting of the International Congress of Zoology, did naturalists begin at last to show a spirit of compromise and adopt a universal code.
Taxonomy is described sometimes as a science and sometimes as an art, but really it's a battleground. Even today there is more disorder in the system than most people realize. Take the category of the phylum, the division that describes the basic body plans of all organisms. A few phyla are generally well known, such as mollusks (the home of clams and snails), arthropods (insects and crustaceans), and chordates (us and all other animals with a backbone or protobackbone), though things then move swiftly in the direction of obscurity. Among the latter we might list Gnathostomulida (marine worms), Cnidaria (jellyfish, medusae, anemones, and corals), and the delicate Priapulida (or little “penis worms”). Familiar or not, these are elemental divisions. Yet there is surprisingly little agreement on how many phyla there are or ought to be. Most biologists fix