Kingdom Animalia Linnaeus, 1758 - animals
   Phylum Mollusca Linnaeus, 1758 - molluscs
     Class Scaphopoda Bronn, 1862 - tusk shells
       1 Family Dentaliidae Children, 1834
       2 Family Laevidentaliidae Palmer, 1974
       3 Family Pulsellidae Boss, 1982
       4 Family Gadilidae Stoliczka, 1868