A new tremataspidid from Ringerike, South Norway

A new tremataspidid genus Tyriaspis (type species T. whitei gen. et sp. nov.) is described from a new Upper Ludlovian locality at Ringerike, southern Norway. The genus is assigned to the subfamily Dartmuthiinae Robertson. Six specimens are known, thus allowing a fairly complete diagnosis and reconstruction of the species which has a flat head-shield with wing-like cornua and dorsal and caudal fins. The scale arrangement of the body differs from that found in typical cephalaspids.