Tabulate corals from Lower/Middle Devonian boundary beds are described. The specimens were recovered from the middle Heisdorf Formation — lower Lauch Formation, ranging from upper Emsian to lowermost Eifelian. The material was collected by Dr. Rolf Werner [†], Forschungsinstitut Senckenberg/Frankfurt, in the early seventies from new trenches (“Richtschnitte”) in Wetteldorf (Prüm Syncline,Werner 1972a), Dingdorf (Prüm Syncline,Werner 1973b, 1975), Lissingen (Gerolstein Syncline,Werner 1973a, 1976) and the Lower/Middle Devonian profile of the “Ahütter Kehre” (Hillesheim Syncline,Werner 1972b). The following taxa have been identified: Favosites (Favosites) gilsoni Lecompte 1939, Favosites (Emmonsia) sollei (Birenheide 1985), and Squameoalveolites straeleni Lecompte 1939; and Heliolites werneri n. sp. is described. Investigation of microstructures in coral skeletons related to boring cyanophyceans allows conclusions on the timing of the diagenesis to be drawn. Endobiontic worm-tubes of Chaetosalpinx huismani Stel 1978 are described.