nt, with probably a rudiment of
the fifth digit in the hind foot; while, in the older forms, the
series of digits will be more and more complete until we come to
the five-toed animals, in which, if the doctrine of evolution is
well founded, the whole series must have taken its origin."

Just as Huxley was successful, when only the ancestry to Miocene times
was known, in predicting the discovery of older forms in the older
Miocene and upper Eocene, so his prediction of older Eocene forms
carrying the chain back to five-toed creatures proved correct. One of
the new links was indeed discovered before his lecture had passed
through the press, and he was able to add in a footnote some details
of the structure of the four-toed Eohippus from the lower Eocene
beds. Further discoveries have connected these with the five-toed
ancestors of the Tapirs, and there is the strongest reason to suppose
that we now know as nearly as possible the line of ancestry of the
horse back to the primitive forms common to all the higher mammals. It
would, of course, be beyond possibility of proof that the exact
fossils described were the actual ancestors of the horse; but that
they are exceedingly close allies of these, and that among them some
actual ancestors exist cannot reasonably be doubted.

Although he had embarked upon geological work with some distaste,
Huxley became very closely associated with it as years went on, and
indeed, about the seventies, had abandoned his intention to devote
himself specially to physiology, and declared himself to be in the
first place a palaeontologist. In 1876 he had accomplished so much that
the Geological Society gave him its chief distinction, awarding him
the Wollaston Medal in recognition of his services to geological
science. He acted as Secretary to the Geological Society from 1859 to
1862, and he was President from 1868 to 1870. In 1862, the President
being incapacitated, Huxley delivered as Deputy-President the
Presidential Address. This address is famous in the history of
geology, because for the first time it stated clearly and in permanent
form a doctrine now taken as a first principle in all geological
text-books. A large part of geology is the attempt to read the past
history of the earth from the evidence given by the successive strata
of rocks that form its crust.

"It is mathematically certain that, in any given vertical linear
section of an undisturbed series