Figure 6. Prodissoconch 2 in Anatomy, shell morphology, and microstructure of the living fossil Pulvinites exempla (Hedley, 1914) (Mollusca: Bivalvia: Pulvinitidae)

Figure 6. Prodissoconch 2 (P2) of the left valve of Pulvinites exempla (juvenile, AMS C.129659, 3.91 mm). The orientation of P2 is given with regard to its placement in the dissoconch. A, dorsal view of the exterior showing the concentric sculpture of P2 and its opisthogyrate placement. The white arrows indicate the P1–P2 transition; the black arrow indicates the metamorphic line. The hinge axis is orientated horizontally with the anterior at the left. B, ventral view showing the interior surface of P2 and the initial crenulation of the hinge plate underlying the first resilium. The arrow indicates the border of confluent scars of the posterior adductor–posterior pedobyssal retractor muscles. C, lateral view of the exterior surface showing the extent of inflation of P2. The white arrow indicates the P1–P2 transition; the black arrow indicates the metamorphic line. lg, resilium of ligament.