An upper cretaceous bed of claystone exposed along the southern bank of Valle El Morro, Baja California, Mexico yielded a large and diversified foraminiferal assemblage of late campanian age. The 46 species and sub-species consist of arenaceous and perforate calcareous types in approximately equal number; benthonic forms predominate among the calcareous foraminifers. It is inferred that the faunule lived in a muddy benthic environment beneath warm, neretic waters of the outer sublittoral zone (100 to 200 meters in depth).
