An unnamed formation from near La Tagua, Colombia, and the Pebas beds of Peru contains ostracod faunas that provide new information on the environment of deposition and the probable age o sediments. The ostracods are a mixture of freshwater, brackish, and marine species, from what was essentially a brackish-water environment. Fifteen species, of which nine are new, are described, together with two subspecies. Three genera — Botulocyprideis, Otarocyprideis, and Rhadinocytherura — are new.
