The Devonian-Carboniferous Boundary sections at Hasselbachtal, Oese, Apricke, and Ober-Rödinghausen,
  all located at the northern margin of the Rhenish Mountains, were measured in detail.  A semi-quantitative
  evaluation of the carbonate content and resulting carbonate curves permitted a highly exact correlation of
  these sections.  This result is supported by data on ammonoid records and volcanoclastic horizons.  
  Carbonate fluctuations within the Hangenberg Limestone are regarded as showing a 100000 years cyclicity.  
  A new ammonoid genus Hasselbachia n. gen. and the species Paprothites ruzhencevi u. sp.  are described.
  Among the rugose corals, a new species Hillaxon hassel n. sp., is erected.