Xii 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 for 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 affording, 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, who 
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. 
IT 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- 
tertown, Jeffersen county ; from Dr. Bupp and Mr. Arson Crarke of Turin, 
nd from Mr. Luxe Witper 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 Witper of Hoosic-falls, and to Dr. A. J. Sxitton and 
Prof. Coox of Troy, for numerous specimens, some of which are already cited 
in this volume, and others will be given in the succeeding one. Mr. Joun 
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. 
i am greatly indebted to the late Mr. Wapteten 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 shquld not omit in this place to make my acknowledgments to my col- 
leagues Mr. Vanuxem and Dr. Emmons, who have both furnished me with 
