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PALAEONTOLOGY OF NEW YORK. 
TROCHOCERAS, Barrande-Hall. 
The genus Trochoceras was proposed by M. Barrande and by myself, about 
the same time, and quite independently of each other, for fossils of identical 
character and structure. The name was first published by M. Barrande— 
my own appearing only in the second volume of the Palaeontology of N. Y., 
Recognizing these facts, M. Barrande has done me the honor to associate 
my name with his own in his subsequent publications of the genus, and I have 
adopted the same course. 
In 1852 J. Hall described Trochoceras Gebhardi and T. turbinatum, from the 
Coralline limestone of the Niagara group ( Palaeontology of New York, vol. 2). 
In 1860 Mr. J. II. McChesney described T. Desplainense, from the Niagara 
group (New Palaeozoic Fossils). 
In 1861 J. Hall described T. Clio and T. eugenium, from the Schoharie grit 
(Fourteenth Rep. N. Y. State Cab. Nat. Hist.); T. costatum , from the Niagara group 
of Wisconsin (Geolog. Survey of Wis.: Rep. of Progress ); and T. discoideum, from 
the Schoharie grit (Desc. New Species Foss.). 
In 1865 Messrs. Meek and Worthen described T. Bceri \==Nautilus], from the 
Hudson-river group (Proc. Acad. Nat. Sci. Phila.). 
Messrs. Winchell and Marcy described Gyroceras Bamisteri [= Trochoceras], 
from the Niagara group of Illinois. 
In 1867 J. Hall described T. notim, from the Niagara group of Illinois 
(Twentieth Rep. N. Y. State Cab. Nat. Hist.). 
In 1869 M. Barrande described T. incipiens, from the Quebec group (Syst. 
Sil. du centre de la Boheme). 
In 1870 J. Hall described T. YFneas, from the Niagara group of Iowa 
(Twentieth Rep. N. Y. State Cab. Nat. Hist.: Revised ed., explanation of pi. 25). 
In 1876 J. Hall illustrated T obliquatum, T. Pandion, Cyrtoceras Orion [=T. 
Orion], from the Schoharie grit (Illustrations of Devonian Fossils); and T. Wal- 
dronense, from the Niagara group of Indiana (Twenty-eighth Rep. N. Y. State Mus. 
Nat. Hist.). 
