Fig. 10 in New Barremian rhynchonellide brachiopod genus from Serbia and the shell microstructure of Tetrarhynchiidae

Fig. 10. Rhynchonellide brachiopod Antulanella pancici (Antula, 1903), Barremian, Crnoljevica, Svrljiške Planine Mountains, eastern Serbia. A. SEM micrographs of transverse sections of the shell RGF VR 24/61. A1. Rib of ventral valve, primary microgranular layer (pl), secondary layer. Silicified organic sheets crossing the section (arrow). A2. Sulcus of ventral valve, primary microgranular layer (pl) above, secondary layer with finer fibrous sublayer, overgrown by diagenetic calcite prisms (dcp). Subparallel silicified organic sheets crossing the shell (arrow). A3. Boundary between the primary microgranular layer and secondary fibrous layer, finer anisometric fibres in the outermost part of the shell, close to boundary; rib of a ventral valve. A4. Anisometric anvil−like fibres of the secondary layer in a sulcus. A5. "Diabolo" type sections of the crura. B. Distal splitting of the crura into parallel plates; better seen on the right crus, specimen RGF VR 25/484 (SEM micrograph taken from an acetate peel).