About 95 per cent of all known animal species are invertebrates. A knowledge of their sexual, reproductive, and developmental biology is essential for the effective management of species that are economically useful to man or are harmful to him, his crops, and livestock. This treatise is the first to cover all aspects of reproduction and development of the entire spectrum of invertebrates?terrestrial, marine, freshwater, brackish-water, free-living, and parasitic. The chapters, by leading world experts in their fields, are up-to-date and informative, and suggest a number of problems for future research. Progress in Male Gamete Ultrastructure and Phylogeny (issued in parts A-C) is the ninth volume in the series. Volume IX, Part B Progress in Male Gamete Ultrastructure and Phylogeny Edited by B.G.M. Jamieson Contents Preface to the Progress Series; Preface to Volume IX B; Contributors; Priapulida, Volker Storch, Claudia Kempendorf, Robert P. Higgins, Thomas C. Shirley, and Barrie G.M Jamieson; Mollusca: Relict Taxa, John M. Healy; Polychaeta, Including Pogonophora and Myzostomida, Gregory W. Rouse; Euclitellata, Marco Ferraguti; Nematoda, Jean-Lou Justine and Barrie G.M. Jamieson; Tardigrada, Lorena Rebecchi, Alessandra Guidi, and Roberto Bertolani; Onychophora, Volker Storch, Hilke Ruhberg, Gerd Alberti, and Barrie G.M. Jamieson; Chelicerata, Gerd Alberti; Subject Index; Species Index.