TJte Scope of Paleontology. -^ Will iam)<. 161 
like those of Agassiz on the echiuoids. Hyatt on the cephalopods 
and those of their followers, Jackson, Beecher and others. But 
at the present time it will be impossible to speak of them, even 
were I able to do them justice. 1 will, however. ])eg your attention 
to a series of paleontological investigations, with the details of 
which I am more familiar, and the steps of which are more or less 
related to each other, and have, colleetiveh, resulted in throwing 
considerable light upon the geology and geography of the Devonian 
system. As I have already said, the Devonian system was originall}' 
founded upon pureh' paleontological evidence. The question as 
to the lower limit of the Devonian in this country has been a 
purely paleontological proljlem, and the reason for including the 
Oriskany in the Devonian is because the fauna is more closely 
allied to that of the Looe and Cornwall slates, the Oedinnien and 
the Coblentzien formations of Europe, than to the Silurian faunas, 
and presents a larger proi)ortion of species which connect it with 
the Corniferous faunas above than with the Helderberg below. 
(See Halls list of species in 42d Annual Keport of New York 
State Museum.) 
The correction of the "Chemung" of Iowa and Missouri and 
the adoption of de Verneuil's earlier interpretations of the Car- 
boniferous age of the fauna as perpetuated in the Kinderhook 
group, was settled by the evidence of fossils. 
The Hercynian question of Europe was debated on paleontolog- 
ical. not stratigraphical grounds. 
In 1881 the minute study of Si>lrifer(i Icevis leading to the pre- 
diction that the character by which Davidson distinguished the 
lower Devonian Sjnri/ent cnrcatti from the Carboniferous Spirl- 
fcra glabra would be found upon the higher form as well, which 
afterwards Davidson confirmed, was the first step toward dis- 
tinguishing the fauna of the upper Devonian of eastern America 
from the middle Devonian fauna as to its origin. 
The suggestive fact in this case was that this rare American 
iipper Devonian spirifer was more closely allied morphologically 
to a common lower and middle European species than to any pre- 
ceding American form. This thought led to a thorough dissec- 
tion of the Devonian faunas of New York and neighboring states. 
The .series of successive faunas along a common meridian were 
tabulated and compared. The sections were made parallel to each 
other and near enough together to make it possible to compare 
