We describe Crithionina delacai, a new large (up to 6.5 mm) agglutinated foraminifer that differs from related species (notably C. granum) in the composition and arrangement of particles within the test. The new species is abundant at a 28-m-deep site in Explorers Cove, McMurdo Sound, Antarctica. This unusually shallow-water occurrence for a species of Crithionina probably reflects the tranquil, cold (-1.8 degrees C), thermally stable, and relatively oligotrophic conditions that prevail at our study site. Crithionina delacai lives infaunally in the top 1 cm of sediment and apparently feeds on diatoms. Its abundance at depths accessible to SCUBA divers provides a unique opportunity to conduct detailed biological studies of this predominantly deep-sea genus.