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 generalisations than
with details. It is my object to mark the epochs of
palaeontology, not to recount all the events of its history.

That which I just now called the fundamental problem of
palaeontology, the question which has to be settled before any
other can be profitably discussed, is this, What is the nature
of fossils? Are they, as the healthy common sense of the ancient
Greeks appears to have led them to assume without hesitation,
the remains of animals and plants? Or are they, as was so
generally maintained in the fifteenth, sixteenth, and
seventeenth centuries, mere figured stones, portions of mineral
matter which have assumed the forms of leaves and shells and
bones, just as those portions of mineral matter which we call
crystals take on the form of regular geometrical solids?
Or, again, are they, as others thought, the products of the
germs of animals and of the seeds of plants which have lost