A new genus and species of pteraspid heterostracan, Mitraspis cracens, gen. et sp. nov., is described from the Early Devonian (Lochkovian) Drake Bay Formation of Prince of Wales Island, Nunavut, Arctic Canada, where it is associated with a rich shallow marine invertebrate fauna. This pteraspid is most closely related to Canadapteraspis based on the arrangement of its sensory canal system, but shows an elongated morphology most similar to that seen in Rhinopteraspis and Althaspis. The unusually elongated rostrum and dorsal spine suggests adaptation for rapid movement. Analysis of the environments in which pteraspids are preserved in the Early Devonian of the Canadian Arctic shows that the same species may have inhabited a variety of environments ranging from deltaic to shallow marine.