† Paleozoic molluscs of uncertain systematic position
† Basal taxa that are certainly Gastropoda
Patellogastropoda
Vetigastropoda
Cocculiniformia
† Paleozoic Neritimorpha of uncertain systematic position
† Cyrtoneritimorpha
Cycloneritimorpha
Caenogastropoda of uncertain systematic position
Architaenioglossa
Sorbeoconcha
Littorinimorpha
Ptenoglossa
Neogastropoda
Lower Heterobranchia
Cephalaspidea
Pteropoda: Thecosomata
Pteropoda: Gymnosomata
Aplysiomorpha
Acochlidiacea
Sacoglossa
Cylindrobullida
Umbraculida
Pleurobranchomorpha
Euctenidiacea
Pseudoeuctenidiacea
Euarminida
Dendronotida
Aeolidida
Basommatophora
Systellommatophora
Elasmognatha
Orthurethra
Sigmurethra