Synopsis Jamoytius kerwoodi White, a Middle Silurian agnathan from the Lesmahagow Inlier, central Scotland, has been the subject of considerable controversy since it was first described in 1946. In a recent review of earlier intepretations of Jamoytius and its affinities Forey and Gardiner ( Bull. Br. Mus. (Nat. Hist.) Geol. 35 , 1981) make statements which are not substantiated by existing material or by evidence from new specimens. A specimen of Jamoytius , used but not figured by the writer in earlier accounts, is now illustrated to clarify the nature and extent of the Jamoytius branchial apparatus. Recent Carboniferous fossil lamprey discoveries strengthen the evidence for a link between Jamoytius and the petromyzontids.