rope.

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).

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. Next, in the backward order
in time, is the _Miohippus,_ which corresponds pretty nearly with the
_Anchitherium_ of Europe. It presents three complete toes--one large
median and two smaller lateral ones; and there is a rudiment of that
digit, which answers to the little finger of the human hand.

The European record of the pedigree of the horse stops here; in the
American Tertiaries, on the contrary, the series of ancestral equine
forms is continued into the Eocene formations. An older Miocene form,
termed _Mesohippus,_ has three toes in front, with a large splint-like
rudiment representing the little finger; and three toes behind. The
radius and ulna, the tibia and the fibula, are distinct, and the short
crowned molar teeth are anchitherioid in pattern.

But the most important discovery of all is the _Orohippus,_ which
comes from the Eocene formation, and is the oldest member of the equine
series, as yet known. Here we find four complete toes on the front limb,
three toes on the hind limb, a well-developed ulna, a well-developed
fibula, and short-crowned grinders of simple pattern.

Thus, thanks to these important researches, it has become evident that,
so far as our present knowledge extends, the history of the horse-type
is exactly and precisely that which could have been predicted from
a knowledge of the principles of evolution. And the knowledge we now
possess