Extensive benthic collections of myodocopid ostracodes made principally from the research vessels Eltanin, Anton Bmun, Hero, and Vema between Antarctica and 35°S, but including some previously reported collections, contain 35 genera, of which 10 are new, and 122 species, of which 60 were previously undescribed. Diagnostic keys are presented to assist in identification. Faunal resemblances between areas based on the Simpson Index are highest between Antarctica and South America, lowest between Antarctica and southern Africa and intermediate between Antarctica and New Zealand and Antarctica and Australia. Four biofacies are delimited: (1)
Skogsbergiella-
Empoulsenia biofacies, which includes shelf and bathyal depths, has outer limits roughly coinciding with the boundary of the Subantarctic region; (2)
Cypridinodes biofacies, which includes shelf and upper slope depths, extends south from the Indo-West-Pacific region and includes Australia and New Zealand; (3) Rutidermatidae biofacies, which is restricted to shelf depths, extends southward into the study area along the coast of Chile; (4)
Spinacopia-
Metavargula-Azygocypridininae biofacies, which is restricted mainly to bathyal and abyssal depths, includes all abyssal and lower bathyal regions of the Antarctic and extends northward into other oceans. The relationship of morphology and feeding habit to distribution is investigated; some new data on reproduction are analyzed; and the microstructure of the carapace, the upper lip, and some appendages is examined with the aid of the scanning electron microscope.
