Several species of opossums, some of them very small, were the only marsupials in North America then, as they are now. There was quite a variety of Insectivora; some were survivals of a family that was abundant in the Eocene, others, like the hedgehogs, moles and shrews, were probably immigrants. Here we find the last of a group (order or suborder) of ancient and primitive flesh-eaters, the †Creodonta, that had played a great rôle in the Eocene and Paleocene of North America and Europe. In White River times but a single family (†Hyænodontidæ), with two genera, remained of the Eocene host. One of these genera (_†Hemipsalodon_), a very large beast of prey, which was almost identical with the Old World genus _†Pterodon_, was confined to the lower substage of the White River beds in the Northwest Territory of Canada; the other, _†Hyænodon_, which was also an Old World form, was represented abundantly in the United States by many species. In size, these species ranged from a small fox to a large wolf, but they all had disproportionately large heads, and small, weak feet, with blunt claws, so that they must have been very curious-looking creatures and were probably carrion-feeders rather than active catchers of prey. The White River members of the family were migrants from the eastern hemisphere, for, though small and primitive representatives of it occurred in the North American Eocene, as well as in the corresponding formations of Europe, the family appears to have died out in America and to have been renewed by the Oligocene migration. [Illustration: FIG. 134.—White River †titanothere (_†Titanotherium robustum_) reduced to the same scale as Fig. 133.]