Llandoverian and Wenlockian graptolites from Bornholm

Silurian (Llandovery and Lower Wenlock) graptolites from Bornholm, Denmark, are discussed. Hundred species and eleven subspecies are described of which five species and two subspecies are new. The ultrastructure of the graptolite rhabdasomes has been investigated and it is concluded that the carbon films show the original graptolite periderm structures. The total thickness of the Silurian sequence is measured to about 160 m. The biostratigraphie zonation of the Silurian on Bornholm is revised, and the sequence is now divided into twelve graptolite zones. The presenee of the persculptus and acuminatus zones in the lowermost Llandovery is demonstrated together with the transition Llandovery-Wenlock. In the stratigraphic review the correlation with corresponding Silurian sequences, especially in Britain and Sweden, is discussed.