Geologists and archæologists are much indebted to Professors Osborn and Obermaier for useful up-to-date summaries of our knowledge of early man, with extensive bibliographies which include most of the latest papers. So much progress has heen made in the study of the subject during recent years—especially since the Prince of Monaco's foundation of the Institute of Human Palæontology in Paris—that synoptical treatises of this kind are an indispensable aid to further advance. Both are also intended, with their beautiful illustrations, to arouse interest in a much wider circle than that of students who are actually engaged in research. They should, indeed, help in urging the educated public to take every opportunity of bringing to the notice of scientific men such casual discoveries of human remains and traces of human handiwork as they happen to meet with. It is lamentable to think how few of these discoveries, even under existing circumstances, are rescued from destruction and made available for study.