Figure 4 in Ontogeny and evolutionary significance of a new acrotretide brachiopod genus from Cambrian Series 2 of South China

Figure 4. Ornamentation and ultrastructure of the earliest ontogeny of Palaeotreta shannanensis gen. et sp. nov. from the Shuijingtuo Formation of southern Shaanxi. A, enlarged ventral apex, note pronounced halo (arrow) and drape structures (tailed arrow), ELI-XYB S4-3 AU-08; B, oblique lateral view of A, showing the pedicle foramen (arrow) and protegulum (tailed arrow); C, posterior view of ventral apex, show enclosed pedicle foramen outside of metamorphic shell, ELI-XYB S4-3 AU-01; D, enlarged dorsal apex, note pronounced halo (arrow) and drape structures (tailed arrow), ELI-XYB S4-3 AV-15 E, obliquely lateral view of D, showing the protegulum (tailed arrow) and two pairs of larval setal sacs (arrows); F, evenly distributed pitting structures on metamorphic shell, ELI-XYB S4-3 AU-13; G, enlargement of F; H, growth lines and drape structures on post-metamorphic shell, ELI-XYB S4-3 AU-13.