An acritarch from the highest Dalradian Macduff Slate of northeast Scotland is confirmed as Veryhachium cf. lairdii. Its presence implies that the Macduff Slate is Ordovician. This conclusion is compatible with the view that there is stratigraphical and structural continuity between the Dalradian and Lower Palaeozoic rocks in the vicinity of the Highland Border (e.g. the Lower Cambrian Keltie Water Grit Formation), but runs counter to other lines of evidence, notably biotite cooling ages, which suggest that the Dalradian had undergone metamorphism by the Late Cambrian. Further investigations are needed to reproduce and confirm the biostrati-graphical evidence for the age of the Macduff Slate.