This paper deals primarily with the systematics of the Caprellidae occuring from the tropical to boreal areas of the western North Atlantic, roughly from the equator to Nova Scotia. The paucity of available material from the east coast of South America prevents consideration of species south of the equator.

Five species of caprellid amphipods occur in Virginia waters: Aeginina longicornis, Hemiaegina minuta, Paracaprella tenuis, Caprella equilibra, and Caprella geometrica. Though all are offshore species, the latter three commonly occur within Chesapeake Bay. Deutella abracadabra is placed as a junior synonym of Paracaprella tenuis and the name Caprella geometrica is assigned to the "acutifrons" form found along the Atlantic and Gulf of Mexico coasts of the United States.