Six species of Spirorbis were recorded from seventeen islands in the Caribbean. All are opercular incubators. Two, S. (Pileolaria) quasimilitaris and S. (Janua) epichysis, were new and two others, S. (P.) koehleri and S. (J.) steueri, were previously recorded only from the Mediterranean, the latter only from Suez. The most abundant species were S. (J.) corrugatus and S. (Leodora) knightjonesi, of which the latter was previously known only from Ceylon, but is closely related to the European species S. (L.) laevis. — The zoogeographical picture shows isolation from the Pacific, as there are no species links with W. México or the Galápagos. It seems that evolution of species has been active since the early Pliocene and that transport has occurred readily along warm-temperate coastlines and across the Atlantic, perhaps on flotsam with the trade winds.