A new genus and species of euphaneropid, Ciderius cooperi, is recorded from the Lower Silurian Fish Bed Formation of the Midland Valley of Scotland on the basis of articulated material. Euphaneropids constitute an enigmatic group which is known from Devonian deposits in Scotland and Canada. The new find adds to our understanding of this group, in particular with regard to the morphology of some common anatomical elements. The paired head stains are here shown to contain clefts which can be interpreted as optic fissures, indicating that these are the remains of eyes. The anterior head stain is reconstructed and demonstrated to be a barrel-shaped object of an uncertain nature. Paired mineralisations situated in the posterior part of the cranial region appear to represent remains of the parachordals, while fossilised blood vessels might be preserved in the form of black lines which mark a greatly elongated branchial region, similar to euphaneropids. Serially repetitive rows of short horizontal stripes on the posterior half of the body are unique for the new taxo, but their interpretation is problematic.
