distinct Varieties.
Falconer's Monograph on living and fossil Elephants.
Fossil Species and Genera of the Horse Tribe in North and
South America.
Relation of the Pliocene Mammalia of North America, Asia,
and Europe.
Species of Mammalia, though less persistent than the Mollusca,
change slowly.
Arguments for and against Transmutation derived from the
Absence of Mammalia in Islands.
Imperfection of the Geological Record.
Intercalation of newly discovered Formation of intermediate Age
in the chronological Series.
Reference of the St. Cassian Beds to the Triassic Periods.
Discovery of new organic Types.
Feathered Archaeopteryx of the Oolite.


CHAPTER 23.

ORIGIN AND DEVELOPMENT OF LANGUAGES AND SPECIES COMPARED.

Aryan Hypothesis and Controversy.
The Races of Mankind change more slowly than their Languages.
Theory of the gradual Origin of Languages.
Difficulty of defining what is meant by a Language as distinct
from a Dialect.
Great Number of extinct and living Tongues.
No European Language a Thousand Years old.
Gaps between Languages, how caused.