iving organism
that the most important position in his work was assigned to them.

Lamarck professes himself unable to make up his mind about extinct
species; how far, that is to say, whole breeds must be considered as
having died out, or how far the difference between so many now living
and fossil forms is due to the fact that our living species are
modified descendants of the fossil ones. Such large parts of the globe
were still practically unknown in Lamarck's time, and the recent
discovery of the ornithorhynchus has raised such hopes as to what might
yet be found in Australia, that he was inclined to think that only such
creatures as man found hurtful to him, as, for example, the megatherium
and the mastodon, had become truly extinct, nor was he, it would seem,
without a hope that these would yet one day be discovered. The climatic
and geological changes that have occurred in past ages, would, he
believed, account for all the difference which we observe between living
and fossil forms, inasmuch as they would have changed the conditions
under which animals lived, and therefore their habits and organs would
have become correspondingly modified. He therefore rather wondered to
find so much, than so little, resemblance between existing and fossil
forms.

Buffon took a juster view of this matter; it will be remembered that he
concluded his remarks upon the mammoth by saying that many species had
doubtless disappeared without leaving any living descendants, while
others had left descendants which had become modified.

Lamarck anticipated Lyell in supposing geological changes to have been
due almost entirely to the continued operation of the causes which we
observe daily at work in nature: thus he writes:--

"Every observer knows that the surface of the earth has changed; every
valley has been exalted, the crooked has been made straight, and the
rough places plain; not even is climate itself stable. Hence changed
conditions; and these involve changed needs and habits of life; if such
changes can give rise to modifications or developments, it is clear that
every living body must vary, especially in its outward character, though
the variation can only be perceptible after several generations.

"It is not surprising then that so few living species should be
represented in the geologic record. It is surprising rather that we
should find any living species represented at all.[244]

"Catastrophes have indeed been supposed,