Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         "crystal-kingdom"
           chemical substances
             chemical compounds
               Class isoprenoids
                 Class terpenoids
                   1 Class hemiterpenoids [C5 skeleton]
                   2 Class monoterpenoids [C10 skeleton]
                   3 Class sesquiterpenoids [C15 skeleton]
                   4 Class diterpenoids [C20 skeleton]
                   5 Class sesterterpenoids [C25 skeleton]
                   6 Class triterpenoids [C30 skeleton] - terpenoids having a C30 skeleton
                   7 Class tetraterpenoids [C40 skeleton] - terpenoids having a C40 skeleton
                   8 Class polyterpenoids [C5n skeleton]