VIII 
PREFACE. 
Plate ii a, and for some other Crinoids and specimens of Eurypterus. 
To 0. Osborn, Esq., and to Mr. Tower of Waterville, I am indebted for 
good specimens of Eurypterus remipes and fragments of Pterygotus. 
Carlos Cobb, Esq., of Buffalo, has allowed me the free use of his very 
fine cabinet of the Waterlime crustaceans, and nearly all those cited 
from Williamsville and the vicinity of Buffalo are from his collection; 
while the collections of the State Cabinet have furnished the beautiful 
new species E. dekayi, and the principal specimens for illustrating the 
E. pachycheirus. 
I am more especially indebted to Mr. William Andrews of Cumberland 
(Maryland), for the very liberal manner in which he has placed at my 
disposal his extensive collections, particularly of the Brachiopoda of 
the Upper Helderberg group and Oriskany sandstone, which, coming in 
at a later period than the study of these forms from New-York*, have 
enabled me to illustrate very satisfactorily the interior structure of 
Rensselaeria, Eatonia, Leptoccelia and Camarium, and to give more complete 
illustrations of many other species which are shown upon the later 
plates. From the Gasteropoda furnished me by this gentleman, I have 
obtained very satisfactory illustrations of the Genus Strophostylus, and 
much instructive material for the study of the Genera Platyostoma and 
Platyceras ; the.specimens being free from adhering stone, and showing 
extreme modifications of the form of the aperture and the incipient 
development of the columellar callosity. All the specimens illustrating 
the Crinoidea of the Oriskany sandstone have been derived from the 
collection of Mr. Andrews. 
Prof. Safford of Tennessee has placed in my hands some interesting 
Specimens from the same group of strata, as well as from other rocks; 
which, together with collections procured from that region of country 
several years since, have enabled me to make some interesting compari¬ 
sons between the faunas of the two localities. 
* I only became aware of the existence of these collections in the latter part of 185G; and in con¬ 
sequence of the accessions from this and other sources, I have given more than a year of additional 
labor to the volume. Could these collections have been in my hands at the outset, it would have been 
greatly to the advantage of the work. 
