Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         "crystal-kingdom"
           chemical substances
             chemical compounds
               Class hydrocarbons [CxHy] - compounds consisting of carbon and hydrogen only
                 Class cycloalkanes - saturated monocyclic hydrocarbons (with or without side chains)
                   1 cyclopropane [C3H6]
                   2.1 cyclopentane [C5H10]
                   3 1,1,3-trimethylcyclohexane [C9H18]