old 
plan of relationship ; we can point to intermediate links which 
distinctly connect modern with ancient animals. 
The pedigree of the horse, which Prof. Huxley has alluded to in 
his ‘ American Addresses,’ as proved by the recent discoveries of 
Prof. Marsh, is familiar to many of you. Prof. Marsh states, that 
ho has himself unearthed with his own hands, not less than thirty 
distinct species of the horse tribe, in the Tertiary deposits of the 
Western States of America alone. Ho has by means of these 
fossils traced the pedigree of our existing horses from a diminutive 
animal of the lower Eocene, Eohippus, which was about the size of a 
fox, had the bones of the fore and hind leg distinct, and had four toes 
and a rudiment on the fore feet, and three toes behind. This 
animal was succeeded in time by the Orohippus, which was 
slightly more equine in its structure than Eohippus. In the 
lower Miocene beds has been found Mesohippus, about the size of 
a sheep, with only three toes and a splint on the fore feet, and 
having the bones of the leg no longer distinct. Mesohippus was 
followed by the upper .Miocene Miohippus , a somewhat larger 
animal ; and in the lower Pliocene by the Protohippus , of the size 
of the ass, which had one toe reaching to the ground, and two 
shorter digits, one on each side of the leg. In the Pliohippus we 
have these short digits becoming mere rudimentary splints, as in 
existing horses. Prof. Marsh says, that there has been a corres- 
ponding transition in the character of the skeleton, skull, teeth, 
and brain, between Eohippus and Equus. Prof. Huxley claims 
these facts as an unmistakable piece of historical evidence, and I 
think few unprejudiced minds will disagree with him, for we 
must not fail to observe that these modifications of structure 
correspond with the relative appearance in time of the animals 
whose remains are thus found in succeeding geological formations. 
It is not, of course, maintained that we have the exact pedigree of 
the horse, but that we have facts to show how in course of ages 
the equine type became modified from its former to its present 
condition. A similar line of collateral relationship was traced by 
Prof. Huxley in 1870, showing the connection of the horse tribe 
with the Hipparion, the Anchitherium and the Plagiopliilus. 
p p 2 
