Fig. 6

Cross sections from late pediveliger larvae of Nodipecten nodosus. Developmental sequence from a–c (anterior to the top). Toluidine blue and basic fuchsin. a Unfolded mantle margin with cilia in the periostracum-forming zone. b Older larva with proximal region of the mantle margin slightly projected forming the inner mantle fold. c Slightly older larva. Two-folded mantle margin with distinctive outer and inner folds. Abbreviations: ci, cilia; fo, foot; if, inner mantle fold; mm, mantle margin; of, outer mantle fold; pe, periostracum; pfz, periostracum-forming zone; pg, periostracal groove; ve, larval velum