On the structure and systematic position of the Genus Rhipidocrinus Beyrich, 1879

A very fine preserved specimen of Rhipidocrinus spec. cf. R. perloricatus W. E. Schmidt, 1905 is described in detail. Special attention in text and figures is drawn to the armstructure. Arms proved to be composed of a monoserial main arm-trunk with biserial ramules placed in alternating order. The first ramules are fixed directly to the dorsal cup and placed regularly at the interradial sides of the radius. The base of Rhipidocrinus is somewhat variably composed i. e. the radials may be in contact with the infrabasal plates. The author believes that this proves Ubaghs correct in regarding zygodiplobathrids and eudiplobathrids as variants of one and the same type of diplobathrid basal organisation.