Articulated thelodonts, Loganellia scotica (Traquair), Shielia gen.n. taiti (Stetson), Lanarkia horrida Traquair, L. spinulosa Traquair and Turinia pagei (Powrie) from the Silurian and Devonian of Scotland are re-described. A new species, Lanarkia lanceolata sp.n. from the Wenlock, Lower Silurian, is established. For each species, diagnosis is specified, varieties of scale morphology are given, the branchial area is described and body morphology is detailed. A paired ventral fin in Shielia gen.n. taiti and Lanarkia lanceolata sp.n. has been discovered. A new reconstruction of Loganellia and Shielia, and diagnosis for thelodonts from Scotland are given. The locality list of Scottish agnathans is reviewed and the biostratigraphical distribution discussed.