The Late Ordovician fauna of the northern Hudson Bay Lowland, Manitoba, Canada, consisting of three stromatoporoid species (1 new), 41 coral (11 new and 2 new genera), 8 gastropod (1 new), 56 cephalopod (21 new and 1 new genus), and 1 graptolite species are described and in part illustrated. Brachiopods are listed only. This fauna was obtained from five formations consisting mostly of fossiliferous dolomitic limestone 300–400 feet thick. In ascending order these are: the Portage Chute and Surprise Creek formations of the Bad Cache Rapids Group; the Caution Creek and Chasm Creek formations of the Churchill River Group; and the Red Head Rapids Formation. The Bad Cache Rapids Group, which rests on peneplaned Precambrian, is correlated with the Red River Formation of southern Manitoba, the Churchill River Group with the Stony Mountain Formation, and the Red Head Rapids Formation questionably with the Stonewall Formation.
The faunas indicate a close temporal relationship between the Bad Cache Rapids and Churchill River groups. The latter is considered Richmondian and in part Gamachian. A Late Ordovician age is thus also suggested for the Bad Cache Rapids Group and hence for the coeval Red River Formation.