f foreign intelligence which has reached us is
the information that the Austrian geologists have, at last, succumbed to
the weighty evidence which M. Barrande has accumulated, and have admitted
the doctrine of colonies. But the admission of the doctrine of colonies
implies the further admission that even identity of organic remains is no
proof of the synchronism of the deposits which contain them.

4. The discussions touching the _Eozoon,_ which commenced in 1864, have
abundantly justified the fourth proposition. In 1862, the oldest record
of life was in the Cambrian rocks; but if the _Eozoon_ be, as Principal
Dawson and Dr. Carpenter have shown so much reason for believing, the
remains of a living being, the discovery of its true nature carried life
back to a period which, as Sir William Logan has observed, is as remote
from that during which the Cambrian rocks were deposited, as the Cambrian
epoch itself is from the tertiaries. In other words, the ascertained
duration of life upon the globe was nearly doubled at a stroke.

5. The significance of persistent types, and of the small amount of
change which has taken place even in those forms which can be shown to
have been modified, becomes greater and greater in my eyes, the longer I
occupy myself with the biology of the past.

Consider how long a time has elapsed since the Miocene epoch. Yet, at
that time there is reason to believe that every important group in every
order of the _Mammalia_ was represented. Even the comparatively scanty
Eocene fauna yields examples of the orders _Cheiroptera, Insectivora,
Rodentia_, and _Perissodactyla_; of _Artiodactyla_ under both the
Ruminant and the Porcine modifications; of _Caranivora, Cetacea_, and
_Marsupialia_.

Or, if we go back to the older half of the Mesozoic epoch, how truly
surprising it is to find every order of the _Reptilia_, except the
_Ophidia_, represented; while some groups, such as the _Ornithoseclida_
and the _Pterosauria_, more specialised than any which now exist,
abounded.

There is one division of the _Amphibia_ which offers especially important
evidence upon this point, inasmuch as it bridges over the gap between the
Mesozoic and the Palaeozoic formations (often supposed to be of such
prodigious magnitude), extending, as it does, from the bottom of the
Carboniferous series to the top of the Trias, if not into the Lias. I
refer to the Labyrinthodonts. As the Address of 1862 was passing through
the press,