Volume 17.2 of the Zoological Catalogue of Australia series deals with four marine mollusc groups. The Aplacophora is a small group of worm or slug-shaped creatures, mostly found on the continental shelf or in deep seas. Polyplacophora, or chitons as they are known, are small, flat, grazing forms with eight calcareous plates embedded in the dorsal surface. Chitons are common in intertidal and shallow coastal waters and are often found by turning over a rock in a tidal pool. The third group, the Scaphopoda, are the tusk or tooth shells, all with a slender, tubular shell, open at each end. These curious molluscs live buried in sand, in littoral to abyssal waters, and may be found washed up on the strand. Lastly, the volume includes the Cephalopoda, the squids, octopods, cuttlefishes and others, many of considerable importance in the fishing industry, others such as the Giant Squid and Blue-Ringed Octopus, marvellously interesting. Each species is cited by name and original references are given to all species known from Australian waters. Information includes synonymy, literature citation, location and status of type material and type locality for each available name, a brief summary of geographical distribution and ecological attributes, and important references on various aspects, especially biology. This catalogue gives fine details of taxonomy and genus and species nomenclature, as well as comprehensive bibliographies for these four marine groups, complementing the family level information provided in Fauna of Australia Volume 5 Mollusca: The Southern Synthesis