Volume 4 groups the second half of the Bivalvia, and the three smaller molluskan class Scaphopoda, Polyplacophora, and Cephalopoda. It documents 1005 different species, with thousands of images, on 301 plates. Collaborating experts in this volume are: Bruno Anseeuw, Gene Coan, Roland De Prins, Henk H. Dijkstra, Takuma Haga, Annie Langleit, Jorgen Lützen, Takashi Okutani, Bernd Sahlmann, Sheila P. Tagaro, Jan Johan Ter Poorten, Rudo von Cosel and Richard C. Willan. The rest of the families has been done by Guido T. Poppe.
This book continues first with the Bivalvia, starting with the popular Propemussiidae and Spondylidae. A long list of smaller families follows, but there is extensive coverage of the amazing Septibranchia, especially of the striking Cuspidariidae. Lucinidae are well covered, including the very deep water ones, as they have been studied by the MNHN. Many species are illustrated for the first time in colour. This is followed by another favorite among collectors: the Chamidae with no less than 18 species. Cardiidae get a full coverage by Jan Johan ter Poorten: a surprising 81 species. Tellinidae, Psammobiidae and Mactridae are other big families in the Philippines.
After the Bivalvia coverage continues with the Scaphopods. Amazingly this small area on the global map has an impressive 78 determinated species. The Cephalopods have been documented as well and there is a superb set of photographs of living animals.
Volume 4 has two Addenda: Addendum I figures no less than 287 species not documented in Volume 1 & 2 because they were either not yet described or not yet discovered at the time of writing, or rediscovered in the Archipelago. Addendum II is an indispensable tool for conchologists working on the mollusks from the Philippines. In 7 pages it gives a summary of the complete literature that concerns this region of the world. This volume completes the main body of the Philippine Marine Mollusks 1 to 4 which now counts not less than 1315 full page A4 colour plates.