In the 10th edition of Systema Naturae, published in 1758, the Swedish naturalist Carl Linnaeus described 554 species of bird and gave each a binomial name. Linnaeus had first included birds in the 6th edition of his Systema Naturae, which was published in 1748. In it he listed 260 species arranged into 51 genera, in turn divided amongst six orders. The entries for each species were very brief; rather than including a description, he gave a citation to an earlier publication — often to his own Fauna suecica, which had been published in 1746. Linnaeus generally followed the classification scheme introduced by the English parson and naturalist John Ray which grouped species based on the characteristics of each species’ bill and feet.