14 New York State Museum 



formations in the State. Where outcrops are small they 

 have necessarily been exaggerated. The former extent of 

 the seas of the different periods as shown in the maps is 

 suggestive only. The sections are generalized and simpli- 

 fied and it has been necessary here, too, where forma- 

 tions are thin to exaggerate the thickness somewhat. 

 Many of the photographs used were taken by Mr E. J. 

 Stein, photographer and draftsman of the State Museum, 

 to whose skill are also due the drawings for the plates 

 of fossils. The photographs illustrating the chapters on 

 life conditions in the sea we owe to the courtesy of the 

 American Museum of Natural History and the Wiscon- 

 sin Natural History Society. 



The writer wishes here to express appreciation to Dr 

 Charles C. Adams, Director of the New York State 

 Museum, for the interest he has shown throughout the 

 whole work and the encouragement he has given. From 

 Doctor Ruedemann, State Paleontologist, likewise, the 

 writer has had interest and encouragement, and she is also 

 indebted to him for reading and criticizing the manuscript. 

 Mr D. H. Newland, State Geologist, and Mr C. A. Hart- 

 nagel, Assistant State Geologist, have assisted in various 

 ways. Dr E. O. Ulrich of the United States Geological 

 Survey, Washington, has read and criticized the manu- 

 script dealing with the Paleozoic formations. The writer 

 is greatly in his debt for many suggestions and for the use 

 of information which has not yet been made available. 

 Thanks are also due Dr Charles Butts of the United 

 States Geological Survey for reading the chapters on the 

 Devonian and Carboniferous. The author has also had 

 the advantage of the viewpoint of Mr Clinton Kilfoyle, 

 technical assistant in Paleontology, who has read the 

 manuscript for both handbooks and has rendered assist- 

 ance in many ways. 



