Microvertebrate assemblages from the Upper Silurian of Cornwallis Island, Arctic Canada

Microvertebrate assemblages from four Upper Silurian (?Ludlow-Pridoli) loca lities on Cornwallis Island, Arctic Canada, comprise mainly scales, plus de ntition cones and jaw fragments from ischnacanthid acanthodians, with rare scales assigned to heterostracan Lepidaspis? sp., ?chondrichthyan Arauzia? sp., and Placodermi? gen. et sp. indet. Most of the scales in sample C-1146 0 are assigned to the poracanthodid acanthodian Poracanthodes canadensis sp .nov., which shows closest affinity to Poracanthodes punctatus Brotzen vari ants from the Baltic Pridoli. The flank scales of the new species resemble those of P. punctatus s.s. (Silurian variant; the zone fossil for the late Pridoli in the Standard Silurian microvertebrate scheme), with their superp osed crown growth zones, rows of small pores aligned with the underlying zo nes, number of radial canals, and "arcade" canals connecting these radial c anals. They differ in having numerous anterior crown riblets, "zig-zag" rat her than straight crown pore rows, and V-shaped arcade canals.