Tin PREFACE. 



Plate II A, and for some other Crinoida and specimens of Euri/pterus. 

 To O. OsBORX, Esq., and to Mr. Tower of Waterville, I am indebted for 

 good specimens of Euryptents remipes and fragments of Pterygotus. 

 Carlos Cobb, E.^q., 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 

 Renssdaria, Eatonia, Leptoccdia and Camarium, and to give more complete 

 illustrations of many other species which are shown upon the later 

 plates. Fro^n 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 

 Platycebas; 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 ray 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 bcc«me aware of the existence of these collections in the latter part of 1850; and in con- 

 aeqiicncc 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 

 grestly to the advantage of the work. 



