Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       naturalia - natural bodies
         "crystal-kingdom"
           chemical substances
             chemical compounds
               Class thioacetals
                 1 Class monothioacetals [R2C(OR')(SR') (R'≠H)]
                 2 Class dithioacetals [R2C(SR')2 (R'≠H)]