Carboniferous
Devonian

Upper Silurian

Lower Silurian

Upper Tertiary Formation

66

Lower Tertiary

Cretaceous

CEPHALOPODS MOL

་.

86

I Paleozoic Age.

Metamorphic Rocks.

CRUST OF THE EARTH AS RELATED TO

ZOOLOGY.

66

CASTEROPODS

ACEPHALA

LUSCA

TOUCHING

THE STRUCTURE, DEVELOPMENT, DISTRIBUTION,

AND NATURAL ARRANGEMENT

OF THE

RACES OF ANIMALS, LIVING AND EXTINCT

WITH NUMEROUS ILLUSTRATIONS.

PART I.

COMPARATIVE PHYSIOLOGY.

FOR THE USE OF SCHOOLS AND COLLEGES.

BY

LOUIS AGASSIZ AND A. A. GOULD.

REVISED EDITION.

BOSTON.

GOULD AND LINCOLN,

59 WASHINGTON STREET.

NEW YORK: SHELDON, BLAKEMAN & CO.

CINCINNATI: GEO. S: BLANCHARD.