There will probably never be enough books on dinosaurs. That they are a subject of endless fascination to all ages is witnessed by the throngs who have seen, with some and more than a few shivers, the Sinclair Rofining Company's dinosaur exhibit at the New York World's Fair. The author was consulting expert during its preparation. He is Assistant Curator of Vertebrate Palaeontology at Yale's Peabody Museum. His text makes a successful effort to be clear and accurate in explaining the knows and discussing the still unknowns of prehistoric reptile life. For each of the vast number of dinosaurs described here, he describes their structure and probable appearance; theorizes about their physical and mental capabilities; and locates their place in geologic time, tracing their evolution and eventual extinction. The proper names of the many species are sounded out in parenthesized phonetics as they occur. The book is generously illustrated with detailed pictures on every page. Unfortunately there are those points where illustrations come either a page or two before or a page or two after the descriptive text. There is also the problem of relative sizes and visual confusion, -- for instance the picture of Antrodemus, (18 ft. high) comes next to that of Compsograthus (""about as big as an ordinary-sized chicken"") yet with only prehistoric shrubbery as a scale guide, they seem to be the same size. This is unfortunate and happens more than once. However, a book that would allow proportionate drawings of dinosaurs would cost considerably more than $3.95. Diagrams. Pronouncing glossary.