CONTENTS. 



PAGE 



II. PALEOZOIC TIME 162 



I. Age of Invertebrates, or Silurian Age ..... 162 



A. Lower Silurian 166 



1. Primordial or Cambrian Period 166 



2. Canadian Period 182 



3. Trenton Period .194 



4. General Observations on the Lower Silurian . . . 210 



5. Disturbances at the close of the Lower Silurian Era . 212 



B. Upper Silurian 218 



1. North American Upper Silurian 218 



1. Niagara Period 218 



2. Salina Period 232 



3. Lower Ilelderberg Period ....... 236 



4. Oriskany Period 241 



2. Foreign Upper Silurian 244 



3. Observations on the Upper Silurian ..... 249 



II. Age of Fishes, or Devonian Age . 254 



1. American 254 



1. Corniferous Period 254 



2. Hamilton Period 266 



3. Chemung Period 276 



4. Catskill Period 279 



2. Foreign Devonian 282 



3. General Observations on the Devonian Age .... 286 



4. Disturbances closing the Devonian Age 289 



III. Carboniferous Age 291 



Subdivisions and American Distribution . . . . . . 291 



1. Subcarboniferous Period 293 



1. American 293 



2. Foreign 306 



3. Disturbances preceding the Carboniferous Period . . 308 



2. Carboniferous Period 309 



1. American 309 



2. Foreign 344 



3. General Observations on the Origin of Coal and the Coal- 



measures 351 



3. Permian Period 367 



1. American 367 



2. Foreign 369 



TV. General Observations on the Paleozoic Ages ... 373 



1. Rocks — Sections of the American Paleozoic Formations in dif- 



ferent States 373 



2. Life 381 



3. American Geography 389 



4. Oscillations of Level — Dislocations 391 



V. Disturbances Closing Paleozoic Time 395 



1. American 395 



2. Foreign 402 



TIL MESOZOIC TIME . . 403 



Reptilian Age 403 



1. Triaseic Period 403 



1. American ........... 403 



