12.1 The Hypothetical Ancestral Mollusc
12.2 Hypotheses of Phylogenetic Relationships of the Major Molluscan Groups
12.2.1 Aculifera – Conchifera, Testaria, and Serialia Hypotheses
12.2.2 The Search for the Molluscan Sister Group
12.3 Repetition of Organs
12.4 Ano-Pedal Flexure and a Change in Body Orientation
12.5 Reduction and Paedomorphosis