This is the second volume of the entirely rewritten, revised and updated version of the original FAO Catalogue of Cephalopodos of the World (1984). It provides accounts for all families and genera, as well as illustrated keys. Information under species accounts includes: valid modern systematic name and origin citation of the species; illustrations of dorsal and ventral aspects of the whole animal and other distinguishing illustrations; field characteristic; diagnostic features; geographic and vertical distribution, including GIS map; size; habitat; biology; a remarks section and literature. This volume is fully indexed and also includes sections on terminology and measurements, an extensive glossary, an introduction with an updated review of the existing biological knowledge on squids and a dedicated bibliography.