The detailed test morphology of the type suite of specimens for the planktonic foraminifer Globigerinoides sacculifer (Brady) is illustrated for the first time since the species was identified in 1877. Fossil representatives of this species are a key index for oceanographic reconstruction of the Neogene and Quaternary tropics. The types of G. sacculifer, sourced from a loose ‘chalk’ block on a beach in New Ireland, Papua New Guinea, all bear a sac-like terminal chamber and are heavily calcified. They have undergone gametogenesis. Scanning electron microscopy identifies calcite fabrics of the test that were formed post-ontogenetically.