The following monograph, by Dr. Roy L. Moodie, adds an important link to the series of paleobiological publications of the Institution and is closely connected with the work already done upon the Permo-Carboniferous vertebrates, since it supplies a description of the life of the period immediately preceding. It is hoped that the volume will contribute in no small measure to an understanding of the broader problems of paleogeography and the recognition of the mutual problems of the paleobiologists and the geologists. E. C. Case. University of Michigan, _March 15, 1916_. PREFACE. The question of the origin of land vertebrates, which has appealed so strongly to students of fossil Amphibia, is by no means solved from the material furnished by the Coal Measures of North America. The Amphibia are, however, well known from several localities in the Coal Measures of this continent, where skeletons have been recovered which are sufficiently well preserved to afford a fair knowledge of their anatomy. The specimens rescued from the dumps of the old mines are regrettably few in comparison with the number that must have been burned as fuel, or carried down the slopes as silt. Yet scanty as is the material thus collected, it is of great importance, because it represents such an early period in the recorded history of the air-breathing vertebrates. The amphibian fauna in the Coal Measures of North America is represented by several hundred individual specimens, preserved in various museums. All of the collections have been available in the preparation of this memoir, with the exception of those species from Nova Scotia which are preserved in the Peter Redpath Museum of McGill University and in the British Museum of Natural History. The European material, which has been used in comparisons with the American forms, has been studied chiefly from the literature, although there have been available a series of specimens of _Branchiosaurus amblystomus_ Credner, from Saxony, presented by the late Professor Credner, and a single specimen of _Archegosaurus_ from Dr. von Huene, of Tübingen.