Natura - nature actualia - actual entities Mundus Plinius - physical world naturalia - natural bodies ["Animale Regnum" nom. inval. - animal kingdom] see Kingdom Animalia Linnaeus, 1758 [Class "Aves" Plinius, nom. inval. - birds] see Class Aves Linnaeus, 1758 [Order "Picae" nom. inval.] see Order Picae Linnaeus, 1758 [Genus "Picus" nom. inval.] see Genus Picus Linnaeus, 1758 1 "Picus niger" nom. inval. 2 "Picus viridis" nom. inval. 3 "Picus varius" nom. inval.