CO NTENTS. 



Page. 



Letter of transmittal 279 



Introduction 281 



Carboniferous - - ■ ■ 288 



Jurassic 289 



Cretaceous 290 



Laramie Group 307 



Appendix I. — North American Tertiary Ostreidse, by Prof. Angelo Heilprin .. . 309 



Eocene 309 



Oligocene 311 



Miocene 312 



Pliocene 314 



Post-Pliocene 315 



Appendix II.— A sketch of the life-history of the oyster, by John A. Eyder.. . 317 



Explanation of plates 334 



275 



