Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       Astra Plinius - celestial bodies
         Universe
           (Supercluster) Virgo-Hydra-Centaurus Supercluster
             (Supercluster) Virgo Supercluster
               (Cluster) Local Group
                 (Galaxy) Milky Way Galaxy veter.
                   (Spiral arm) Orion Arm
                     (Region) Local Bubble
                       Local Interstellar Cloud
                         (Planetary system) Solar System
                           (Planet-satellite system) Earth System
                             (Planet) Earth veter.
                               "spheres" (Earth)
                                 (Sphere) Hydrosphere (Earth) - layer of water
                                   (Drainage basin) Atlantic Ocean Basin
                                     (Drainage basin) American Mediterranean Sea Basin (America)
                                       (Drainage basin) Gulf of Mexico Basin
                                         (Drainage basin) Mississippi River Basin (United States, Canada)
                                           (Drainage basin) Red River Basin (North America)
                                             (Drainage basin) Little River Basin (United States: Oklahoma, Arkansas)
                                               (Stream) Mountain Fork (United States: Arkansas, Oklahoma)