Abstract:
Five species of nuculoid bivalves are described from Pennsylvanian outcrops of the Ixtaltepec Formation, Oaxaca, Mexico: Nuculopsis sp., Palaeoneilo sinuosus new species, Paleyoldia sp., Phestia bellistriata, and Phestia sp, have been collected in elastic rocks and in association with other marine invertebrate groups, which represent a peri-reefal environment.