Natura - nature actualia - actual entities Mundus Plinius - physical world naturalia - natural bodies "crystal-kingdom" chemical substances chemical compounds Class alcohols [ROH (R≠H)] Class amino alcohols Class sphingoids 14 tetradecasphinganine [14 carbon atoms] 18.35 (4E,14E)-sphinga-4,14-dienine [C18H35NO2; HOCH2CH(NH2)CH(OH)CH=CH[CH2]8CH=CH[CH2]2CH3] 18.37 "sphingosine" [C18H37NO2; HOCH2CH(NH2)CH(OH)CH=CH[CH2]12CH3] 18.39 sphinganine [C18H39NO2; HOCH2CH(NH2)CH(OH)[CH2]14CH3] 20 icosasphinganine [20 carbon atoms]