Often as the story has been told, the Epsteins have done it again with a clarity that makes their book definitive enough to give young interests a well rounded amplification of the subject. The statement that there are two branches to the study of paleontology- learning of the animals themselves and how man has found out about them- sets the stage for following material. Starting with the ""how"", the Epsteins tell us that the Greeks voiced suspicions of a prehistoric life 2000 years ago. They then bring us up to the beginnings of modern paleontology in the work of William Smith, whose study of stratified rocks in England led to the naming of the different periods of animal development. The periods themselves. 500,000,000 ago and the age of trilobites, the age of fish, landward migration, early reptiles and so on up to mammals and man- are freshly described with a clarity to make them memorable. And as evolutionary theories, most brilliantly transmitted by Darwin, came to have meaning for the transitions, they too are enumerated.