Mr. Croll's Views on Ancient Glacial Epochs--Effects of Denudation in Destroying the Evidence of Remote Glacial Epochs--Rise of Sea-level Connected with Glacial Epochs a Cause of Further Denudation--What Evidence of Early Glacial Epochs may be Expected--Evidences of Ice-action During the Tertiary Period--The Weight of the Negative Evidence--Temperate Climates in the Arctic Regions--The Miocene Arctic Flora--Mild Arctic Climates of the Cretaceous Period--Stratigraphical Evidence of Long-continued Mild Arctic Conditions--The Causes of Mild Arctic Climates--Geographical Conditions Favouring Mild Northern Climates in Tertiary Times--The Indian Ocean as a Source of Heat in Tertiary Times--Condition of North America During the Tertiary Period--Effect of High Excentricity on Warm Polar Climates--Evidences as to Climate in the Secondary and Palaeozoic Epochs--Warm Arctic Climates in Early Secondary and Palaeozoic Times--Conclusions as to the Climates of Secondary and Tertiary Periods--General View of Geological Climates as Dependent on the Physical Features of the Earth's Surface--Estimate of the Comparative Effects of Geographical and Physical Causes in Producing Changes of Climate. _Pages_ 169-209 CHAPTER X THE EARTH'S AGE, AND THE RATE OF DEVELOPMENT OF ANIMALS AND PLANTS Various Estimates of Geological Time--Denudation and Deposition of Strata as a Measure of Time--How to Estimate the Thickness of the Sedimentary Rocks--How to Estimate the Average Rate of Deposition of the Sedimentary Rocks--The Rate of Geological Change Probably Greater in very Remote Times--Value of the Preceding Estimate of Geological Time--Organic Modification Dependent on Change of Conditions--Geographical Mutations as a Motive Power in Bringing about Organic Changes--Climatal Revolutions as an Agent in Producing Organic Changes--Present Condition of the Earth One of Exceptional Stability as Regards Climate--Date of Last Glacial Epoch and its Bearing on the Measurement of Geological Time--Concluding Remarks _Pages_ 210-237 {xv} PART II INSULAR FAUNAS AND FLORAS CHAPTER XI THE CLASSIFICATION OF ISLANDS Importance of Islands in the Study of the Distribution of Organisms--Classification of Islands with Reference to Distribution--Continental Islands--Oceanic Islands _Pages_ 241-245 CHAPTER XII OCEANIC ISLANDS:--THE AZORES AND BERMUDA _The Azores, or Western Islands_ Position and Physical Features--Chief Zoological Features of the Azores--Birds--Origin of the Azorean Bird-fauna--Insects of the Azores--Land-shells of the Azores--The Flora of the Azores--The Dispersal of Seeds--Birds as seed-carriers--Facilities for Dispersal of Azorean Plants--Important Deduction from the Peculiarities of the Azorean Fauna and Flora _Pages_ 246-262 _Bermuda_