of denudation.
On the poorness of our palaeontological collections.
On the intermittence of geological formations.
On the absence of intermediate varieties in any one formation.
On the sudden appearance of groups of species.
On their sudden appearance in the lowest known fossiliferous strata.


CHAPTER 10. ON THE GEOLOGICAL SUCCESSION OF ORGANIC BEINGS.

On the slow and successive appearance of new species.
On their different rates of change.
Species once lost do not reappear.
Groups of species follow the same general rules in their appearance
and disappearance as do single species.
On Extinction.
On simultaneous changes in the forms of life throughout the world.
On the affinities of extinct species to each other and to living
species.
On the state of development of ancient forms.
On the succession of the same types within the same areas.
Summary of preceding and present chapters.


CHAPTER 11. GEOGRAPHICAL DISTRIBUTION.

Present distribution cannot be accounted for by differences in
physical conditions.
Importance of barriers.
Affinity of the productions of the same continent.