Structure and microstructure of Pachypora lamellicornis LINDSTROM, 1873, a tabulate coral from the Silurian of Gotland, Sweden

摘要

The examination of types and topotypes of the type species of Pachypora (Pachypora lamellicornis LINDSTROM, 1873), from the Upper Visby Beds, Lower Wenlock, District of Visby, Gotland (Sweden), facilitates enhanced characterization of morphology, structure and microstructure of this genus. Calices are very small, rounded or crescentic, sometimes spiny, tabulae sparse, only angle mural pores present, pore plate probably lacking, lateral increase with basal pore. Wall microstructure well preserved: median lamina built of granules in the axial zone of the branch, small plates in its margin, lacking in the peripheral zone; main layer of sclerenchyma (very thick in the peripheral zone) composed of scutellate microlamellae coated in the axial zone by a fibrous layer sometimes topped by a thin film of microlamellae. No obvious growth lamellae were noted. A comparison between Pachypora and Platyaxum is attempted.