It was long before he learned to shape and adjust the stone to the end of the stick, and to hurl this by means of a cord attached to a second and elastic stick—in other words, a bow; still longer before he discovered the art of fashioning clay into vessels and of polishing and boring stones. These simple arts are landmarks in the progress of the race: the latter divides the history of culture into the palæolithic or rough stone period, and the neolithic or polished stone period; while the shaping of a stone for attachment to a handle or shaft marks the difference between the epoch of compound implements and the earlier epoch of simple implements, both included in the older or palæolithic age.[16] With these principles as guides, we may ask how far back on this scale do the industrial relics in America carry us? I have spoken of the great antiquity of some of the American shell-heaps, how they carry us back to the diluvial epoch, and that of numerous extinct species. Yet it is generally true that in the oldest hitherto examined in Brazil, Guiana, Costa Rica and Florida, fragments of pottery, of polished stone, and compound implements, occur even in the lowest strata.[17] Venerable though they are, they supply no date older than what in Europe we should call the neolithic period. The arrow-heads which have been exhumed from the loess of the ancient lake-beds of Nebraska, the net-sinkers and celts which have been recovered from the auriferous gravels of California, prove by their form and finish that the tribes who fashioned them had already taken long strides beyond the culture of the earlier palæolithic age. The same is true, though in a less degree, of the chipped stones and bones which Ameghino exhumed from the lacrustine deposits of the Pampas, although he proves that these relics were the products of tribes contemporary with the extinct glyptodon and mylodon, as well as the fossil horse and dog. In the very oldest station which he examined, there appears to have been found a quartz arrow-head; yet he argues that this station dated from the pliocene division of the tertiary, long anterior to the austral glacial epoch.[18] This leaves another such open conflict between geology and the history of culture, as Professor Rau has already pointed out as existing in Californian archæology. There is, however, one station in America which has furnished an ample line of specimens, and among them not one, so far as I know, indicating a knowledge of compound implements. This is that of the “Trenton gravels,” New Jersey. There we appear to be in face of a stage of culture as primitive as that of the stations of Chelles and St. Acheul in France, absolutely without pottery, without polished stone, without compound implements.[19]