x CONTENTS. 
CHAPTER IV. 
The breaks in the paleontological and geological record—Use of 
the term ‘‘ contemporaneous” as applied to groups of strata— 
General sequence of strata and of life-forms interfered with by 
more or less extensive gaps — Unconformability—Phenomena im- 
plied by this—Causes of the imperfection of the paleontological 
record, . : . : : : : : - : 44-52 
CHAPTER V. 
Conclusions to be drawn from fossilsK—Age of rocks—Mode of origin 
of any fossiliferous bed—Fluviatile, lacustrine, and marine de- 
posits—Conclusions as to climate—Proofs of elevation and subsi- 
dence of portions of the earth’s crust derived from fossils, . 52-56 
CHAPTER JV. 
The biological relations of fossils—Extinction of life-forms—Geolo- 
gical range of different species—Persistent types of life—Modern 
origin of existing animals and plants—Reference of fossil forms 
to the existing primary divisions of the animal kingdom—Depart- 
ure of the older types of life from those now in existence—Re- 
semblance of the fossils of a given formation to those of the for- 
mation next above and next below—Introduction of new life- 
forms,” *~. : : : : : : ; : ‘ 57-61 
PAR D1. 
HISTORICAL PALAZZONTOLOGY. 
CHAPTER VII. 
The Laurentian and Huronian periods—General nature, divisions, 
and geographical distribution of the Laurentian deposits— Lower 
and Upper Laurentian—KReasons for believing that the Lauren- 
tian rocks are not azoic based upon their containing limestones, 
beds of oxide of iron, and graphite—The characters, chemical 
composition, and minute structure of Hozod Canadense—Compar- 
ison of Zozodn with existing Foraminifera— Archeospherine— 
Huronian formation—Nature and distribution of Huronian de- 
posits— Organic remains of the Huronian—Literature, - 65-76 
CHAPTER. VI 
The Cambrian period—General succession of Cambrian deposits in 
Wales—Lower Cambrian and Upper Cambrian—Cambrian de- 
posits of the continent of Europe and North America—Life of the 
Cambrian period — Fucoids— Eophyton—Oldhamia— Sponges— 
Echinoderms—Annelides— Crustaceans—Structure of Trilobites 
—Brachiopods—Pteropods, Gasteropods, and Bivalves—Cephalo- 
pods—Literature, . : : ' ‘ ‘ ; ; 77-90 
