Of all the animals the birds are the best known and most early recognised. The study of comparative anatomy and of the fossil evidence of ancient life has convinced zoologists that birds are unquestionably descended from reptiles. "Birds are glorified reptiles" and many zoologists have preferred to combine birds and reptiles in a single class the Sauropsida which means reptile like animals. The birds are far more reptilians in their organisation than the mammals. The evolution of feather presumably from scales of reptilians type conferred obvious advantages for the avian flight. The Archiaeopteryx and Archaeornis though bridge the reptiles and birds, but still the early fossil remains of birds are scarce. This book is designed to approach the morphology, anatomy, physiology and development of the Birds in encyclopaedic manner. Profusely illustrated, this book features both a text and a laboratory guide. It deals with the structures and physiological phenomena of each system. Origin, adaptive radiation and other general topics are also dealt in details. It is hoped that this work will not only meet the requirement of Indian students but will also be useful as a guideline to the teachers in their teaching.