In Europe, a Lower Ordovician conodont zonation can be established for the calcareous, partially condensed succession of the Baltic Shield. Sporadic conodont occurrences in the graptolitic shale facies can be correlated with this zonation. The Tremadocian to Llanvirnian Series are dealt with, and eleven conodont zones are established in these series. From below, these are the zones of Cordylodus angulatus, Paltodus deltifer (both Tremadocian), Paroistodus proteus, Prioniodus elegans, P. evae (corresponding to the Arenigian extensus Zone), Baltoniodus triangularis, B. navis, Paroistodus originalis, Microzarkodina parva (corresponding to the main part of the Arenigian hirundo Zone), and Amorphognathus variabilis (top of hirundo Zone, Llanvirnian bifidus Zone). For handling the material, some new taxa have had to be described. The taxonomy is based on multielement species, where such can be established. The multielement species are defined on morphologic and statistical criteria, as well as on the pattern of evolution. The taxonomic approach allows a more "natural" classification on the suprageneric level than the form-taxonomy previously used for this material. An evolutionary pattern is discernible for the drepnodids (each species containing drepanodiform and oistodiform elements) and the prioniodids (species containing prioniodiform elements, branched compound elements with symmetry transition, and oistodiform elements). On a suggestion from Professor O. H. Walliser, elements belonging to multielement species are distinguished by adding the ending "-form" to the name of the genus they would have been brought to in a purely formal taxonomy. The word formed in this way is an adjective. The following new taxa are named: Drepanoistodus gen. nov., Paroistodus, gen. nov., Protopanderodus, gen. nov., Stolodus, gen. nov., Baltoniodus, gen. nov., Microzarkodina, gen. nov., Microzarkodina parva n. sp., M. ozarkodella n. sp. The following genera are redefined: Oistodus, Scandodus, Scolopodus, Drepanodus, Paltodus, Prioniodus, Gothodus.