Figure 5 in Phylogeny of families in the Pectinoidea (Mollusca: Bivalvia): importance of the fossil record

Figure 5. Diagrammatic shell structure map of Propeamussium modified from Waller (1972). The dotted lines outline calcitic internal ribs that are covered by the aragonitic inner layer. Muscle scars and pallial lines are areas of secretion of aragonitic myostracum.