Carboniferous

Devonian

Upper Silurian

Lower Silurian

Upper Tertiary Formation

Lower Tertiary

Cretaceous

Oolitic

Trias

CEPHALOPODS MOL

1 Paleozoic Age.

Metamorphic Rocks.

CRUST OF THE EARTH AS RELATED TO

ZOÖLOGY.

ACEPHALA

S CA

CASTEROPODS

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 AND COMPANY.

CINCINNATI: GEO. S. BLANCHARD.

Entered, according to Act of Congress, in the year 1851
BY GOULD AND LINCOLN,

In the Clerk's Office of the District Court for the District of Massachusetts.