The various kinds of buccal organ recognised by Rouse and Fauchald (1997) are here mapped onto the same tree that was used to develop their new classification of polychaetes. In this transformation a simple ventral buccal organ represents the primitive condition for polychaetes and subsequently transforms into the other kinds of buccal organs. The simple axial proboscis would appear to have evolved twice independently, as would the loss of any kind of buccal organ