The textile fabrics, wooden objects, and other things of perishable materials, except where buried in caves in the dry Southwest, have long ago disappeared, and therefore, to make comparisons, one must inspect the older forms among ethnological objects in the collections at New York, Chicago, Denver, Washington, Milwaukee, Cambridge, Toronto, etc., for illustration. There are many hafted implements of various kinds in existence in museums to-day—particularly in the case of specimens collected one hundred years ago—which present trustworthy evidence as to how similar things may have been mounted in prehistoric times. Again, there are hundreds of modern objects collected in the past century among living tribes that to the student of archæology appear to exhibit white man’s influence and are of little or no value in understanding real Stone-Age times. As an illustration of this, I mention the various forms of catlinite pipes, recent examples of which are quite degenerate as compared with the old forms. The same is true of most of the Pueblo pottery, and the war-clubs of Plains tribes. [Illustration: FIG. 26. (S. 2–3.) Flint knives, made of red and yellow jasper. William C. Mills, Columbus, Ohio. ] It seems strange that with the thousands of pages on archæological and ethnological subjects, with which our libraries are filled, no such classification was attempted previously. The time is certainly opportune for such a work and while I am aware that the following pages are more or less incomplete, still I believe that some one should make a beginning, even though the future observers, who will know much more regarding these interesting and mysterious artifacts of the past than do we of the present, may question some of the observations herein set forth. [Illustration: FIG. 27. (S. 1–2.) Flint cores from which the knives are made. Specimen to the left, red and yellow jasper. Specimen to the right, maroon colored jasper. Flint Ridge material. William C. Mills, Columbus, Ohio. This and some thirty other figures loaned by Mills, appeared in the publications of the Ohio State Archæological and Historical Society, and illustrated his explorations. ] I suggest that the critical reader bear in mind that a classification of all the implements of the United States brings out certain facts or tendencies, or may indicate conclusions which escape the observer who is interested in the exploration of a given territory rather than in a study of types, or who is not familiar with the implements of most of the United States. Therefore, “The Stone Age” is narrowed to a description of the ornaments, utensils, weapons, and artifacts of ancient man in America. Otherwise, one could easily fill ten volumes instead of two, and even then not exhaust the subject.