The suborder Cladocopa comprises 3 genera and about 41 living species, which are worldwide in distribution. Most Recent species are limited to the coastal waters of northwestern Europe and the Mediterranean Sea. Fossil occurrences are limited to Europe, with the exception of 4 specimens found near the top of a North Atlantic sediment core, Large forms from the Paleozoic of Europe are referable to the family Leperditellidae rather than to the Cladocopa. Recent Cladocopa are found exclusively in waters of normal salinity, and seem to prefer water temperatures between 4 degrees and 14 degrees C. Although collected occasionally at depths of 1280 to 2600 m., they are usually found in waters less than 500 m. deep. The geologic evidence indicates that the anterior shell concavity was a late acquisition and may be an adaptation permitting more efficient swimming. If so, this may enable the Cladocopa to complete more successfully, and thus may account for the relatively large number of Cladocopa existing at the present time. A new species of the genus Polycope from the Great Bahama Bank is described and figured. Important papers concerning Recent Cladocopa are included in the bibliography.

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