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 Vermes Linnaeus, 1758 - worms see Phylum Vermes (C. Linnaeus, 1758) Order Zoophyta Linnaeus, 1758 Genus Hydra Linnaeus, 1758 Hydra umbellaria Linnaeus, 1758