Four Malmian corals of different microstructures have been described: Thamnasteria concinna, Dimorpha straea sp., Actinaraeopsis exilis and Isastraea cf. bernensis. Aragonite coral tissue being preserved, histological observations have been initiated. Taxonomical value of microstructure and histology, as decisive for suprageneric division, is confirmed. In four discussed species, trabeculae are of a branched morphology and non-sclerodermitic structure. Each species represents a different variety of trabecular histology. A restricted significance of synapticulae for taxonomical purposes is confirmed. Are described vertical adtrabecular bars, a new skeletal element in Th. concinna.

Key words: Scleractinia, morphology, microstructure , histology of skeletal, tissue, taxonomy, Oxfordian, Poland.