This vast collection has yielded
evidence bearing upon the question of the pedigree of the horse of the
most striking character. It tends to show that we must look to America,
rather than to Europe, for the original seat of the equine series; and
that the archaic forms and successive modifications of the horse's
ancestry are far better preserved here than in Europe.
Professor Marsh's kindness has enabled me to put before you a diagram,
every figure in which is an actual representation of some specimen which
is to be seen at Yale at this present time (Fig. 9).
[Illustration: FIG. 9.]
The succession of forms which he has brought together carries us from
the top to the bottom of the Tertiaries. Firstly, there is the true
horse. Next we have the American Pliocene form of the horse
(_Pliohippus_); in the conformation of its limbs it presents some very
slight deviations from the ordinary horse, and the crowns of the
grinding teeth are shorter. Then comes the _Protohippus_, which
represents the European _Hipparion_, having one large digit and two
small ones on each foot, and the general characters of the fore-arm and
leg to which I have referred. But it is more valuable than the European
_Hipparion_ for the reason that it is devoid of some of the
peculiarities of that form--peculiarities which tend to show that the
European _Hipparion_ is rather a member of a collateral branch, than a
form in the direct line of succession.
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