CONTENTS. 



CHAPTER IV. 



The breaks in the palseontological 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 palaeontological 

 record, 44-52 



CHAPTER V. 



Conclusions to be drawn from fossils — 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 VI. 



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 hfe from those now in existence — Re- 

 semblance of the fossils of a given fomiation to those of the for- 

 mation next above and next below — Introduction of new life- 

 forms, o 57-61 



PART II. 

 HISTORICAL PALEONTOLOGY. 



CHAPTER VII. 



The Laurentian and Huronian periods — General nature, divisions, 

 and geographical distribution of the Laurentian deposits — Lower 

 and Upper Laurentian — Reasons 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 Eozobn Canadense — Compar- 

 ison of Eozoon with existing Foraminifera — AfchceosphcBrince — 

 Huronian formation — Nature and distribution of Huronian de- 

 posits — Organic remains of the Huronian — Literature, 65-76 



CHAPTER Vin. 



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 — Eophy ton — Oldhamia — Sponges — 

 Echinoderms — Annelides — Crustaceans — Structure of Trilobites 

 — Brachiopods — Pteropods, Gasteropods, and Bivalves — Cephalo- 

 pods — Literature, 77-9° 



