It describes in detail an additional 600-odd species not previously covered in Walter Cernohorsky’s first two volumes. Thirty-six of these shells have been selected for reproduction in precise colour and there are 64 black and white plates depicting a further 587 shells. This authoritative new volume also records taxonomic changes affecting some species described in the first two volumes and incorporates some nomenclatural changes. As in the previous volumes, the geographical area of the molluscan fauna covered extends from the Marquesas, in the Eastern Pacific, to West New Guinea.