318 
PALEONTOLOGY OF NEW YORK. 
GOMPHOCERAS, Sowerby. 1839. 
The genus Gomphoceras avrs not recognized in any American publication 
until 1857, Avhen Mr. Billings described G. obesum, from the Utica group, and 
G. subgracilis , from the Upper Silurian ( Geol. Surv. of Canada: Rep. Progress). 
In 1860 Mr. Hall described G. Conradi, G. Fischeri and G. oviformc, from the 
Hamilton group ( Thirteenth Rep. State Cab. Nat. Hist.). 
In 1861 Mr. Hall described G. eximium, from the Upper Helderberg lime¬ 
stone ( Fourteenth Rep. State Cab. Nat. Hist.), and G. beta, from the Schoharie grit 
(.Descriptions of New Species of Fossils, p. 44). 
In 1862 Mr. Hall republished the description of G. beta, from the Schoharie 
grit ( Fifteenth Rep. State Cab. Nat. Hist., p. 72). 
In 1866 Mr. Winchell described G. omicron, from the Hamilton group of 
Michigan (Rep. Lower Peninsula, Mich.). 
Meek and Worthen described G. turbiniforme, from the Hamilton group ( Proc. 
Acad. Nat. Sci. Phila.) 
In 1867 Mr. Hall described G. septoris, from the Niagara group of Wisconsin, 
and G. scrinium, from the same horizon in Illinois (Twentieth Rep. State Cab. 
Nat. Hist.). 
In 1875 Hall and Whitfield described G. eos, from the Iludson-river 
group (Geol. Surv. of Ohio: Pal., vol. 2). 
In 1876 Mr. Hall illustrated Cyrtoceras clavatum [= Gomphoceras], from the 
Schoharie grit, and Cyrtoceras gibbosum [= Gomphoceras oviformc ], from the 
Hamilton group (Illus. of Devon. Foss.). 
From the geological distribution of the species, as indicated in the above 
historical sketch, it is shown that the greater number belong to formations 
above those of recognized Silurian age. The additional species described 
in the present volume will considerably increase this proportion. The 
confusion now existing among the heretofore described forms, from an uncer¬ 
tain generic reference, renders any attempt at a digest of the Avhole impos¬ 
sible without a revision and examination of all the species recorded under 
