THE GEOLOGICAL RECORD.

On the absence of intermediate varieties at the present day--On the nature
of extinct intermediate varieties; on their number--On the vast lapse of
time, as inferred from the rate of deposition and 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

279-311

CHAPTER X.

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

312-345

CHAPTER XI.

GEOGRAPHICAL DISTRIBUTION.

Present distribution cannot be accounted for by differences in physical
conditions--Importance of barriers--Affinity of the productions of the same
continent--Centres of creation--Means of dispersal, by changes of climate
and of the level of the land, and by occasional means--Dispersal during the
Glacial period co-extensive with the world

346-382

CHAPTER XII.

GEOGRAPHICAL DISTRIBUTION--_continued_.

Distribution of fresh-water productions--On the inhabitants of oceanic
islands--Absence of Batrachians and of terrestrial Mammals--On the relation
of the inhabitants of islands to those of the nearest mainland--On
colonisation from the nearest source with subsequent modification--Summary
of the last and present chapters

383-410

CHAPTER XIII.

MUTUAL AFFINITIES OF ORGANIC BEINGS: MORPHOLOGY: EMBRYOLOGY: RUDIMENTARY
ORGANS.

CLASSIFICATION, groups subordinate to groups--Natural system--Rules and
difficulties in classification, explained on the theory of descent with
modification--Classification of varieties--Descent always used in
classification--Analogical or adaptive characters--Affinities, general,
complex and radiating--Extinction separates and defines groups--MORPHOLOGY,
between members of the same class, between parts of the same
individual