speciality, the mass of materials with which it has to deal is already
prodigious. In the last fifty years the number of known fossil remains
of invertebrated animals has been trebled or quadrupled. The work of
interpretation of vertebrate fossils, the foundations of which were
so solidly laid by Cuvier, was carried on, with wonderful vigour and
success, by Agassiz in Switzerland, by Von Meyer in Germany, and
last, but not least, by Owen in this country, while, in later years, a
multitude of workers have laboured in the same field. In many groups of
the animal kingdom the number of fossil forms already known is as great
as that of the existing species. In some cases it is much greater; and
there are entire orders of animals of the existence of which we should
know nothing except for the evidence afforded by fossil remains. With
all this it may be safely assumed that, at the present moment, we are
not acquainted with a tittle of the fossils which will sooner or later
be discovered. If we may judge by the profusion yielded within the last
few years by the Tertiary formations of North America, there seems to be
no limit to the multitude of mammalian remains to be expected from that
continent; and analogy leads us to expect similar riches in Eastern
Asia, whenever the Tertiary formations of that region are as carefully
explored. Again, we have, as yet, almost everything to learn respecting
the terrestrial population of the Mesozoic epoch; and it seems as if
the Western territories of the United States were about to prove as
instructive in regard to this point as they have in respect of tertiary
life. My friend Professor Marsh informs me that, within two years,
remains of more than 160 distinct individuals of mammals, belonging to
twenty species and nine genera, have been found in a space not larger
than the floor of a good-sized room; while beds of the same age have
yielded 300 reptiles, varying in size from a length of 60 feet or 80
feet to the dimensions of a rabbit.

The task which I have set myself to-night is to endeavour to lay before
you, as briefly as possible, a sketch of the successive steps by
which our present knowledge of the facts of palaeontology and of those
conclusions from them which are indisputable, has been attained; and I
beg leave to remind you, at the outset, that in attempting to sketch
the progress of a branch of knowledge to which innumerable labours
have contributed, my business is rather with g