This volume comprises the systematic treatment of 32 species (of 21 genera) of strophomenid brachiopods from the Ordovician-Silurian of Anticosti Island. Four new species and a new family are named, and a number of biozones are recognized through this sequence. In biogeographic terms, the strophomenid fauna is derived from two biogeographic assemblages, with the maximum faunal replacement of one biogeographic suite by the other occurring well below the systemic boundary.