Early Bashkirian Rugosa (Anthozoa) from the Donets Basin, Ukraine. Part 3. On the genera Cyathaxonia Michelin, 1847 and Barytichisma Moore and Jeffords, 1945

Fedorowski, J. and Vassilyuk, N.P. 2011. Early Bashkirian Rugosa (Anthozoa) from the Donets Basin, Ukraine. Part 3. On the genera Cyathaxonia Michelin, 1847 and Barytichisma Moore and Jeffords, 1945. Ada Geologica Polonica, 61(2), 133-152. Warszawa. The genus Cyathaxonia Michelin, 1847 is determined to be one of only two possible genera belonging in the family Cyathaxonidae Milne Edwards and Haime, 1850. This detailed study of a new species, Cyathaxonia nodosa, proves the origin of the columella independent of major septa, as demonstrated in crossed nicols. The inner margins of the major septa retreat from the corallite axis in the late neanic growth stage. The presence of a circulotheca is considered to be an important feature of this genus. Barytichisma represented by Barytichisma sp, is placed in the family Stereophrentidae Fomichev, 1953.