_Hyracotherium_ lived in the south-eastern part of England—his remains occur in the London Clay near Herne Bay and in the Red Crag of Suffolk—_i.e._, in deposits formed two or three or it may be six million years ago. This ancient fossil horse—though not unlike a long-faced fox terrier—Owen regarded as a relation of the Hyrax or Coney of Palestine, hence the name _Hyracotherium_. Evolved in Western Europe—perhaps in England—this primitive small-brained terrier-on-hoofs not only wandered across Europe and Asia, but actually crossed into America—then freely connected with north-eastern Asia—and ranged at least as far south as New Mexico. So conservative was this small forerunner of the great horse family that the American representative from the Wasatch deposits only differs from the parent form in having slightly more complex teeth. The fore and hind foot of the American variety of _Hyracotherium_—generally known as _Eohippus_—is represented in fig. 10, and fig. 12 gives a restoration of _Eohippus_. Though at the beginning of the Eocene period the milk-givers were backward and small (_Eohippus_ was probably only 12 inches at the withers), the struggle for existence was probably keen enough. At any rate, the European varieties of _Hyracotherium_ either died off without leaving descendants or gave rise to odd-toed ungulates which took no part in forming the modern Equidæ. But for the American branch of the _Hyracotherium_ family there would have been no horses. In course of time _Eohippus_ was supplanted by _Protorohippus_ (a 14-inch horse longer in the limbs and with more complex teeth), which towards the close of the Eocene period gave place to the still more specialised _Orohippus_. It may be mentioned that _Epihippus_, a slightly modified descendant of _Orohippus_, may have lived side by side with the remote ancestor of the camels—a quaint even-toed ungulate about the size of a “jack-rabbit.” The limbs of _Orohippus_[F10] are represented in fig. 11, and a restoration is given in fig. 13. [F10] In the Yale collection there are five species of _Orohippus_ from New Mexico and Wyoming. [F11] R. S. Lull, ‘American Journ. of Science.’ 1907.