_Hypohippus_, like _Eohippus_, but unlike all the known Oligocene horses, had in the fore limb, in addition to three complete and functional toes, a distinct vestige of the first metacarpal—_i.e._, of the bone which in man carries the thumb. No vestige of a first metacarpal has ever been found in slender-limbed breeds, but once and again a vestige of the first metacarpal occurs in coarse-limbed breeds. The vestigial first metacarpal, taken along with other facts, suggests, as already said, that coarse-limbed breeds include a browsing race with limbs of the _Hypohippus_ type amongst their ancestors. A few years ago it was assumed that _Hypohippus_, the 40-inch forest horse of Dakota and Montana, became “extinct during the Miocene, leaving no descendants.”[F13] Now, however, it is admitted that browsing horses possibly “identical with _Hypohippus_ of the Miocene of America”[F14] lived in China at the beginning of the Pliocene. Though it is inconceivable that a species with the short-crowned teeth of _Hypohippus_ could give rise to any of our modern breeds, it is possible that in the Pliocene of Eastern Asia a race (with _Hypohippus_-like limbs but long-crowned molars) may be found bearing the same relation to long, low, big-boned modern “forest” horses that _Merychippus_ bears to fine-boned modern plateau or desert horses. [F13] Lull, _loc. cit._, p. 177. [F14] Osborn, ‘Age of Mammals,’ p. 333. The fore-foot of _Hypohippus_ is represented in fig. 20. When a toe corresponding to the second digit of _Hypohippus_ (II. fig. 20) appears in a modern horse it has sometimes, as in _Hypohippus_ and _Eohippus_ (I. fig. 10), a vestige of the first metacarpal at its upper. Fig. 15 is a restoration of _Hypohippus_. _Ponies in Prehistoric Times._—During the Pleistocene period some eight or more species of true horses and ponies inhabited North America. Apparently before Palæolithic man reached the New World all these American species had become extinct. About the American true horses which, like _Hipparion_, reached and found a home in Eastern Asia, very little is known. Some of their descendants found their way during Pliocene times into India; others reached south-eastern Europe. One of the Indian Pleistocene species (_E. namadicus_) from the Narbada valley had large long-pillared molars like _E. complicatus_ of North America and _E. fossilis_ of England (fig. 22); another (_E. sivalensis_), well represented in Pliocene deposits of the Indian Siwaliks, is the oldest true horse about which we have definite information. Like _Pliohippus_, _E. sivalensis_ had short-pillared molars, but instead of measuring, like _Pliohippus_, 12 hands at the withers, this Indian species reached, in some cases, a height of 15 hands.