At first sight the palæontological strata of South America, in which the presence of man has been proved by Ameghino, appear to give a very different picture. The animal forms occurring here contemporaneously with man deviate to such an extent from those familiar to us in the Drift of the Old World that it required the keen eye and the complete grasp of the whole palæontological material of the world that characterise Von Zittel to recognise and establish the connections here, while the discoverer himself thought that he must date his discoveries of man back to the Tertiary Period. The strata in which the earliest traces of man as yet appear to be proved in South America are the extensive “loess-like” loam deposits of the so-called “pampas” formation in Argentina and Uruguay, with their almost incomparable wealth of animal remains, particularly conspicuous among which are gigantic representatives of edentates that now occur only in small species in South America: Glyptodontia (with the gigantic _Glyptodon reticulatum_) and dasypoda; also of the gravigrada, the giant sloth (_Megatherium americanum_). The toxodontia were also large animals, now extinct. But besides the specifically South American forms, numerous “North American immigrants” also appear in the pampas formation. It was only at the close of the Tertiary Period that the southern and northern halves of America grew together into one continent, and the faunæ of North and South America, so characteristically different, then began to intermingle with one another. The South American autochthons migrate northward; on the other hand, North American types--as the horse, deer, tapir, mastodon, _Felis_, _Canis_, etc.--use the newly-opened passage to extend their range of distribution. The northern animal forms are very conspicuous among the animal world of South America, hitherto cut off from North America and characterised by the above-mentioned wonderful and, in part, gigantic edentates, marsupials, platyrhine apes, etc. Of the great elephantine animals of North America only the mastodon crossed over to South America. In the middle and latest Tertiary formations the genus mastodon is widely distributed over Europe, North Africa, and South Asia. In North America the oldest species of the mastodon appear in the Middle Tertiary (Upper Miocene), but the most species are found in the latest Tertiary (Pliocene) and the Drift (Pleistocene); in South America the mastodon is limited to the time of the pampas formation. Its tusks are long and straight, or slightly curved upward; its lower jaw also possesses two tusks, which project in a straight direction, but are considerably less than the upper tusks in size. From the results of Ameghino’s investigations man appears to have come to South America with these northern immigrants, especially with the mastodon. In Ameghino’s lists of the animals of the pampas formation Von Zittel describes man, like the animal forms