Fig. 8 in The morphology and fine structure of the Ordovician Cephalodiscus-like genus Melanostrophus

Fig. 8. Melanostrophus fokini Öpik, 1930; Upper Ordovician (Kukruse Stage, C β), Ubja (Estonia); ZPAL Pb 6/1. SEM micrographs. A–C. Inner periderm 2 surface where removal of the enamel−like inner lining reveals cortical fibrils of endocortex beneath. D. Enlargement of cortical fabric in endocortex. Abbreviations: b1, b2, b3, adjacent bundles of cortical fibrils; c, cortical fibril; d, mineral debris; en, endocortex; i, inner lining; t, transverse connecting fibril.