Fig. 11 in The Early Cambrian (Botomian) stem group brachiopod Mickwitzia from Northeast Greenland

Fig. 11. Mickwitzia cf. occidens Walcott. Fragmentary mature valves (indeterminate) MGUH 26280 (A), MGUH 26314 (B), MGUH 26315 (C), MGUH 26316 (D). A1. Section through primary and secondary layer with large tube and smaller acrotretoid−type columns; scale bar 20 µm. A2. Detail of large tube perforating primary layer of A1; scale bar 20 µm. A3. Detail of tubular wall of A1 showing adhering cocci and possibly annulations; scale bar 5 µm. B1. Detail of secondary layer with acrotretoid−type columns and laminar shell; scale bar 20 µm. B2. Detail of B1 showing median slit between laminae and cover of adhering discoidal structures; scale bar 5 µm. C. Detail of secondary layer with numerous acrotretoid−type columns and single large tube; scale bar 20 µm. D. Detail of secondary layer with thin laminae with median slit and acrotretoid−type columns and single cross−section through large tube; scale bar 20 µm. All specimens from the Ella Island Formation, sample GGU 314816.