Nine agnostoid species from late Cambrian (Paibian: Steptoean) boulders from the Cow Head Group in western Newfoundland fall into three biostratigraphically distinct faunas. The Glyptagnostus reticulatus Fauna contains only the eponymous species and correlates with the lower part of the Paibian and the basal Steptoean of North America. The “Innitagnostus” inexpectans Fauna is more diverse and likely correlates into part of the lower Steptoean Aphelaspis Zone of western North America. The youngest fauna, the Acmarhachis kindlei n. sp. Fauna, also includes species of Homagnostus and Pseudagnostus, as well as a second new species of Acmarhachis, A. whittingtoni. It probably correlates with the Dunderbergia Zone (mid-Pabian and mid-Steptoean) of the western United States. The Laurentian species Acmarhachis typicalis Resser (1938) and A. acuta (Kobayashi, 1938) are evaluated from restudy of type material, and types of “Innitagnostus” inexpectans (Kobayashi, 1938) from British Columbia are also reillustrated.