Slowly, over more than a century & a quarter, the history of Permian terrestrial vertebrates has been pieced together by discovery & study of fossil-bearing strata in all of the continents except Australia & Antarctica. The decade of the 1950s has been exciting from the standpoint of new discoveries both in North America & abroad. New finds have gone far toward bridging the gaps between the lower & upper Permian & have presented new & quite revolutionary data on the distribution of Permian terrestrial faunas. Contents of this study: Introduction, Systematics, Geology, Interpretations, & Evolution. Illustrations. This is a print on demand edition of an important, hard-to-find publication.