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CONTENTS.

Geographical distribution dependent on Geologic Changes — A Law

deduced from well-known Geographical and Geological facts—The

form of a true system of Classification determined by this Law—Geo-

graphical Distribution of Organisms—Geological Distribution of the
forms of Life—High Organization of very ancient Animals consistent
with this Law—Objections to Forbes' Theory of Polarity—Rudi-
mentary Organs—Conclusion . . * * . . Pp. 1–25

Test of true and false Theories—Importance of the Principle of Utility
—Popular Theories of Colour in Animals—Importance of Conceal-
ment as influencing Colour—Special modifications of Colour—Theory
of Protective Colouring—Objection that Colour as being dangerous
should not exist in Nature—Mimicry—Mimicry among Lepidoptera
—Lepidoptera mimicking other Insects—Mimicry among Beetles—
Beetles mimicking other Insects—Insects mimicking Species of other
Orders—Cases of Mimicry among the Wertebrata—-Mimicry among
Snakes—Mimicry among Birds—Mimicry among Mammals—Objec-
tions to Mr. Bates' Theory of Mimicry—Mimicry by Female Insects
only—Cause of the dull Colours of Female Birds—Use of the gaudy
Colours of many Caterpillars—Summary—General deductions as to
Colour in Nature—Conclusion . e o e . Pp. 45—129

WI.-The Philosophy of Birds' Nests.

What Natural Selection can Not do—The Brain of the Savage shown
to be Larger than he Needs it to be—Size of Brain an important
Element of Mental Power—Comparison of the Brains of Man and of
Anthropoid Apes—Range of intellectual power in Man—Intellect of
Savages and of Animals compared—The use of the Hairy Covering
of Mammalia—The Constant absence of Hair from certain parts of
Man's body a remarkable Phenomenon—Savage Man feels the want
of this Hairy Covering—Man's Naked Skin could not have been pro-
duced by Natural Selection—Feet and Hands of Man considered as

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ON THE LAW WHICH HAS REGULATED THE INTRODUCTION OF NEW SPECIES."

Geographical Distribution dependent on Geologic
Changes.

EVERY naturalist who has directed his attention to the subject of the geographical distribution of animals and plants, must have been interested in the singular facts which it presents. Many of these facts are quite different from what would have been anticipated, and have hitherto been considered as highly curious, but quite inexplicable. None of the explanations attempted from the time of Linnaeus are now considered at all satisfactory; none of them have given a cause sufficient to account for the facts known at the time, or comprehensive enough to include all the new facts which have since been, and are daily being added. Of late years, however, a great light has been thrown upon the subject by geological investigations, which have shown that the present state of the earth and of the organisms now

* Written at Sarawak in February, 1855, and published in

the “Annals and Magazine of Natural History,” September, 1855.

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