PREFACE. 



has been wrought out. Situated where I can have no recourse to scientific 

 friends except by letter, with a scanty library of works on Paleontology, and 

 no authentic collections tor the comparison of species already described, I 

 have been forced to depend upon my own resources in every department. I 

 cannot therefore but suppose, that those who have devoted themselves to the 

 study of some particular department, with greater facilities than are within 

 my reach, will find many things, which, under better auspices, could have 

 been made more perfect. I can only content myself with having represented 

 in the engravings, as accurately as possible, every object described in this 

 volume; thus aflbrding, to those who desire to do so, the means of com- 

 paring species, and of correcting any erroneous references. 



I must here acknowledge my obligations to my friend James D. Dana, Avho 

 has given me some valuable suggestions in regard to the corals ; and had it 

 been possible to do so, I should have submitted the whole of this class of 

 fossils to his examination and decision. 



I am indebted to many kind friends for specimens loaned or given to me 

 for this work. I have received many fine ones from Dr. I. B. Crawe of Wa- 

 tcrtown, Jeflerson county ; from Dr. Budd and Mr. Ai,son Clarke of Turin, 

 and from Mr. Luke Wilder of Lowville, Lewis county. 



I am under obligations to Gen. Spinner of Mohawk, for several fine speci- 

 mens from the lower strata, and for others from a higher position which do 

 not appear in this volume. I am likewise indebted to Mr. W. H. Pease of 

 New- York, to Mr. Lyman Wilder of Hoosic-falls, and to Dr. A. J. Skilton and 

 Prof Cook of Troy, for numerous specimens, some of which are already cited 

 in this volume, and others will be given in the succeeding one. Mr. John 

 Gebhard junior, of Schoharie, has allowed me the free use of his valuable 

 cabinet, which has furnished several fine specimens for the present volume, 

 and will be of the most essential importance in illustrating the middle and 

 higher groups. 



1 am greatly indebted to the late Mr. Wadleigh of Middleville; and the 

 extensive collections purchased from him have enabled me to present many 

 new forms, as well as to illustrate in a much more perfect manner others not 

 contained in my previous collections. 



I should not omit in this place to make my acknowledgments to my col- 

 leagues jNIr. Vanuxem and Dr. Emmons, who have both fiirnished me with 



