CONTENTS 
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Introduction 5 
Chapter I. — The principles of correlation 10 
Importance of correlation : 10 
Correlation division of the United States Geological Survey . 10 
Dual nomenclature ..... 11 
Definitions and nomenclature of f aunal paleontology . . 18 
Animal and plant aggregates 13 
Zoological and botanical classification 15 
Distribution and range 10 
Geological faunas and their nomenclature 20 
Nomenclature of formations 27 
Faunal aggregates 28 
Chapter II. — The geological expression of faunal migrations. _ 33 
Migration as a stimulus to variation . 40 
Chapter III. — Faunal dissection of Middle and Upper Devonian of the 
New York province 42 
Introduction of a faunal classification of the Devonian system. . 45 
Revised classification of faunas 48 
The statistics and the plan of discussion 49 
Hamilton formation and Tropidoleptus carinatus fauna 50 
Tropidoleptus carinatus fauna of eastern counties of New York 
and Pennsylvania 51 
Distributional values of the species 52 
Frequency values of the species . _ 52 
Range values of the species . 53 
Cayuga Lake section 54 
Eighteenmile Creek section ... 5 '< 
Construction of a standard list of the dominant species of the Tropido- 
leptus carinatus fauna 58 
Effect of additional statistics 02 
Statistics based on analysis of the zones of the Livonia salt shaft. 08 
Hamilton formation in Ontario, Canada _ . 04 
Hamilton formation in Michigan 65 
Hamilton formation in Wisconsin . 65 
Hamilton formation in southern Illinois , . . 66 
Sellersburg formation in Indiana 66 
Romney formation in western Maryland 07 
Absence of Tropidoleptus fauna in other regions 68 
Post-Hamilton formations and their faunas in New York province 68 
Fauna of eastern extension of Portage formation 71 
Fauna of Ithaca formation as expressed in the typical locality at 
Ithaca, N.Y 73 
Productella speciosa fauna < 6 
Immigrant species of Ithaca formation 7S 
Mutation and correlation of the faunas - 81 
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