MORPHOLOGICAL DETAILS OF THE GENUS NUBECULINA CUSHMAN, 1924

A Holocene sediment sample from 110 m water depth on the Papuan Shelf yielded a population of Nubeculina divaricata (Brady). The most signif icant feature observed was a thin, calcareous, perforate inner layer, in addition to the thick, calcareous imperforate or porcelaneous outer layer characteristic of the miliolids. Where the uniserial chambers e mbrace the aperture and upper chamber surfaces of the preceeding chamb er, the inner layer detaches from the outer layer and curves upward to attach to the embraced apertural lip or neck. The genus Nubeculina Cu shman may represent a fundamental taxonomic division within the subord er Miliolina Delage and Herouard, based on the presence of this extra, perforate layer.