Eukaryota  >  Metazoa  >  Mollusca  >  Gastropoda  >  Cycloneritida

Family	Genus	Species
Helicinidae	6	9
Hydrocenidae	2	63
Neritidae	14	196
Neritiliidae	2	6
Neritopsidae	2	2
Phenacolepadidae	9	50