This book is a revision and expansion of of a classic work that treats all of the molluscan species recorded from the Panamic province-the tropical and subtropical shores of the Eastern Pacific and the offshore islands as far as the Galapos. Includes the malacology, cataloging, systematizing, and illustrating of most of the molluscan species likely to be recorded from the region-lays the groundwork for the studies of evolution, physiology, behavior, and ecological relationships. This edition has been extended geographically to northwestern Peru and includes the deepwater species and shell-to-shell mollusks. Some 3,325 species are treated and also included are synopses for all taxonomic groups of these species, four coastal maps, list of excluded species, source data on illustrations, and an index to all recognized names and synonyms, illustrations, and color plates illustrating 85 species including nudibranchs and other opisthobranchs.