Robert W. Pennak's "Fresh-water Invertebrates of the United States" is a comprehensive 769-page treatise published by The Ronald Press Co. in 1953. The book is a valuable resource for both American and European limnologists, as it addresses the challenges faced by scientists in accessing each other's scientific literature. Pennak, a student of Professor C. Juday, provides an in-depth analysis of various freshwater animal groups, including their morphology, behavior, reproduction, and ecology. Each chapter includes general biological and morphological introductions, summarizing classical and recent research, with many important American studies from wartime and post-war periods. The book features over 2000 detailed illustrations, aiding in species identification. Despite the difficulty of covering all freshwater invertebrate groups from Protozoa to Molluscs, Pennak's work is well-critiqued and corrected by specialists, ensuring its accuracy. The book's clear text and attractive layout encourage further limnological research on North American freshwater fauna. It is also a valuable addition to the libraries of European limnologists. The book is recommended for its thorough coverage, detailed illustrations, and contributions to the understanding of freshwater invertebrates.Robert W. Pennak's "Fresh-water Invertebrates of the United States" is a comprehensive 769-page treatise published by The Ronald Press Co. in 1953. The book is a valuable resource for both American and European limnologists, as it addresses the challenges faced by scientists in accessing each other's scientific literature. Pennak, a student of Professor C. Juday, provides an in-depth analysis of various freshwater animal groups, including their morphology, behavior, reproduction, and ecology. Each chapter includes general biological and morphological introductions, summarizing classical and recent research, with many important American studies from wartime and post-war periods. The book features over 2000 detailed illustrations, aiding in species identification. Despite the difficulty of covering all freshwater invertebrate groups from Protozoa to Molluscs, Pennak's work is well-critiqued and corrected by specialists, ensuring its accuracy. The book's clear text and attractive layout encourage further limnological research on North American freshwater fauna. It is also a valuable addition to the libraries of European limnologists. The book is recommended for its thorough coverage, detailed illustrations, and contributions to the understanding of freshwater invertebrates.