Imperium naturæ C. Linnaeus, 1758 - nature Mundus Plinius - physical world naturalia - natural bodies Regnum Animale C. Linnaeus, 1758 - animal kingdom see Kingdom Animalia Linnaeus, 1758 Class Aves Linnaeus, 1758 - birds see Subclass Aves Linnaeus, 1758 Order Grallae Linnaeus, 1758 Genus Ardea Linnaeus, 1758 Ardea americana Linnaeus, 1758 see Grus americana (Linnaeus, 1758)