The new edition of P.J. Bentley’s established text describes the physiological mechanisms utilized by different vertebrate species to adapt to the differences and vicissitudes of water and salt availability in their natural environments. The book is especially concerned with the roles of endocrine glands in coordinating and maintaining such osmoregulation. It provides information about the environmental stresses and physiological and endocrine processes involved in the osmoregulation in each phyletic order of the vertebrates, and it describes the physiological adaptations they have evolved to foster their survival in osmotically hostile habitats. The second edition provides a comprehensive update utilizing the considerable amount of new data which have been collected over the past years. From a review of the previous edition: I strongly recommend it as an essential reading and reference book for younger and older workers alike . Nature