Eurypterids from the Early Devonian of the Midland Valley of Scotland

A new specimen of Parahughmilleria sp. is described from the Early Devonian Dundee Formation (Arbuthnott Group, Lochkovian) from the Tillywhandland Qu arry (Forfar) in the Midland Valley of Scotland. The diversity of eurypteri ds from the Midland Valley assemblage is reinterpreted to comprise six spec ies (although systematic revisions await the discovery of more material and formal revisions of each genus): Pterygotus anglicus Agassiz, 1844 (includ ing Pterygotus minor Woodward, 1864, here interpreted as a juvenile), Tarso pterella scotica Woodward, 1872 (including Erieopterus brewsteri Woodward, 1864, here interpreted as a juvenile), Stylonurus powriensis Page, 1856 (in cluding Stylonurus? ensiformis Woodward, 1864, here interpreted as a partia l piece (telson) of a large individual), Pagea sturrocki Waterston, 1962, N anahughmilleria pygmaea Salter, 1859 and Parahughmilleria sp. Functional ev idence and their general occurence favours a benthonic mode of life for the stylonurids. which inhabited fluvial systems surrounding 'Lake Forfar', wh ereas the pterygotids and hughmillerids inhabited the lacustrine facies.