Abstract
Synopsis: The unique specimen of Coccosteus angustus Traquair, from the Lower Devonian Hunsrückschiefer of Germany, is redescribed and referred to Gemuendenaspis n.gen. Previously unrecorded details of its morphology and a reconstruction are given. Its possession of both arctolepid and brachythoracic characters is confirmed and it is suggested that Gemuendenaspis should be referred to the family Gemuendenaspidæ nov., which closely approaches what would be expected in ancestors of the Coccosteidæ.