This volume is based on the contributions presented at the symposium "Comparative Aspects of the Structure and Develop ment of the Forebrain in Lower Vertebrates", held on September 2-3, 1988, as a Satellite to the Annual Meeting of the European Neuroscience Association at the University of Zurich-Irchel. Within the two days the symposium lasted, the main topic, of course, had to be covered in an exemplary rather than a comprehensive way. However, the comparative interpretation of results revealed many similarities of forebrain organization in the wide spectrum of species considered. Besides a great deal of new data on forebrain structure and development, this book contains attempts based on various new methodological approaches to find homologies between brain structures of non mammalian vertebrates and mammals. Although we are still far from having unequivocal solutions for the latter problem, the contributions to this volume illustrate impres sively that comparative neuroscientists have better chances than ever of gaining new insights since they now have at their disposal a still increasing number of refined anatomical and physiological techniques such as immunocytochemistry, tract tracing of inject ed markers, and intracellular stimulation and recording. A promi nent contribution from the rapidly evolving field of molecular biology can be anticipated. A lot of stock taking will have to be done; yet, the bulk of studies using modern methods have been dealing with the mammalian brain.