One of the most highly quoted works in vertebrate development literature.... still the definitive work in this field. -- Trends in Genetics An instant classic when it was first published, this remarkable book has lost none of its usefulness in the intervening three decades. It describes the embryology of Xenopus, making this adaptable frog a model for embryological study. Even scientists armed with today's sharp molecular tools are still in need of an unimpeachable easily readable map of the spatial and temporal changes in the anatomy of experimental organisms. With ten plates of detailed anatomical drawings, this book provides an accurate and easy-to-use map of each developmental stage, supported by a clear and readable text. In the new preface, two contemporary scientists describe this rigorous work as a guide for the study of "the most important problems in vertebrate embryology". This useful work remains a classic -- even in the age of computers.