Prof. _Cyrus Thomas_ brings the qualification which a lifetime devoted to study of the subject develops, to the preparation of an _Introduction to the Study of North American Archæology_.[57] He is known to all students in this branch as a careful, judicious investigator whose work in the field has been supplemented by valuable contributions to its literature. In this volume he presents a brief summary of the progress that has been made in the investigation of American antiquities--which has been recently great indeed, and well calls for a new synopsis. His chief object has been to present the data and arrange them so as to afford the student some means of bringing his facts and materials into harmony, and of utilizing them. He presents the theories that have been advanced, and mentions opposing views; regarding it, he says, as important to the progress of the student to know which of the questions that arise have been answered, and which hypotheses have been eliminated from the class of possibilities. The materials for the study and the methods are first explained. The relics of ancient men and the mounds are then described as under three divisions--the Arctic, the Atlantic, and the Pacific. Local as well as regional characteristics and differences are pointed out; as in the mounds as a whole, the special class of animal mounds, the pueblos, the cliff dwellings, and the Mexican and Central American monuments, the peculiar features of each are pointed out, and their territorial limits are defined. All these various kinds of works are ascribed to substantially the same people, who are supposed to have come down from somewhere in the north or northwest (the extreme northwest Pacific coast), although the different immigrations may perhaps have arrived by various routes. The people were the present Indians or their ancestors; the time of the immigration was not extremely remote; and the "mound-building habit" is shown to have persisted and been practiced till since the advent of the Europeans.