The material investigated is from a rocky outcrop of the Lena Dura formation about 50 miles southwest of Punta Arenas, Brunswick peninsula, Magallanes province, southernmost Chile. The formation has been variously considered Oligocene or Eocene in age. The floral component from one level seems to offer firm evidence for an Eocene age. The marine algae, especially Deflandrea, dominate the microflora. The microplankton consists of dinoflagellates, hystrichospheres, and acritarchs, including Baltisphaeridium severinii n. sp. New records for both South America and the southern hemisphere are established.