made from those parts of the Argentine zoogeographic Benthic foraminifera from the southwestern Atlantic have been studied since 1839. However, despite the appearance province whose benthic foraminiferal fauna was poorly known. To supplement the material housed in the Buenos of about 60 articles dealing with the benthic foraminiferal Aires collection, the senior author visited various insti- fauna of this area, there is no single work which has at- tutions to study the original material of investigators such tempted to synthesize the taxonomy, distribution, and ecology of the fauna. Many of the published papers deal as d'Orbigny, Williamson, Brady, Cushman, and Heron- with portions of the area, and one is even a summary of the Allen and Earland. Due to space limitations we have figured and described only those species which are im- zoogeography and ecology of South America (Boltovskoy, portant by virtue of their abundance, widespread lateral 1976). It is one purpose of this work to bring together in one place the descriptions and illustrations to accompany extent or restriction to a single subprovince or environ- and amplify the zoogeographic and ecologic work done in ment. the past. The majority of the samples on which this study is The nomenclature of benthic foraminifera has un- based were not preserved at the time of their collection.