Natura - nature
   actualia - actual entities
     Mundus Plinius - physical world
       particles
         elementary particles
           elementary fermions - elementary particles with half-integer spin
             antileptons
               1.1 positron C.D. Anderson, 1933 - anti-electron
               1.2 electron antineutrino
               2.1 antimuon
               2.2 muon antineutrino
               3.1 antitau
               3.2 tau antineutrino