Dionide Barrande 1847 and Dionidella Prantl & Pribyl 1949 (Dionididae, Trilobita) from the Ordovician of the Ebbe Anticline (Rhenish Massif, Germany). Neues Jahrbuch fuer Geologie und Palaeontologie Monatshefte, 10, Oktober 1998: 613-625. 621 [Zoological Record Volume 135]