The next culture-group is that of central and western Pennsylvania, wherein many New Jersey and New York State types occur. The problematical forms, the black chert, arrow-points, the jasper knives, and the notched hoes or axes may be said to enable one to distinguish this region from other culture-groups of the East, even if they are more or less related. West Virginia may be said to lie on the border-line between Pennsylvania, Kentucky, and Ohio. Hematite appears in the valleys of the Kanawha and other streams in West Virginia. The monitor pipes also appear, together with certain forms of axes, spear-heads, and knives which are found in greater numbers in Kentucky and Ohio. Ohio and Kentucky stand as two separate cultures separated by the Ohio River. Yet the Ohio River was made use of by prehistoric man from above Pittsburg to its mouth at Cairo. Along the stream itself one may discern, on both north and south bank sites, all kinds of cultures, thus proving that the Ohio River was not only a thoroughfare but _the_ thoroughfare in prehistoric times. It is only when one proceeds up the streams from the Ohio back fifty or a hundred miles in Illinois, Kentucky, Indiana, and Ohio that one observes how the local cultures have developed. The culture of the Muskingum and Scioto in Ohio are practically the same; the Miami is different. The Wabash in Indiana is yet another culture and the Illinois yet a third. In Kentucky the Cumberland and Tennessee are in a class by themselves, separate from the others mentioned. These two latter rivers are so long, and as each is navigable far into the State of Tennessee, I feel certain that five or six cultures may be clearly differentiated within their valleys. I have referred to the stone-grave culture of this region elsewhere. It merits further detailed study on the part of archæologists. In the State of Illinois are long yellow chert spear-heads and lance-heads and knives, some of which have slightly turned points. Many of these are not unlike the Scandinavian daggers. In Michigan and Wisconsin there is a wealth of copper, many of the sugar quartz spears and knives, large numbers of peculiar winged problematical forms which have been quite fully illustrated in this work. The Illinois and Wisconsin cultures are separate and distinct. Northern Illinois contains types of Wisconsin and Michigan as well as numbers of central Illinois forms. At Sandwich in DeKalb County there is a large collection owned by Mr. Henry W. Franck, who sent me numerous photographs of his exhibit. This collection illustrates the mingling of types of three cultures and is of great archæological importance.