904 THE JOURNAL OF GEOLOGY. 
ment. At the period of deposition of the Hamilton beds in 
New York, a distinct fauna had to come to exist in each of these 
two areas. 
The east American fauna of this time has been described 
and illustrated chiefly in the various reports of the New York 
state geologist. From studies of the South American Devonian 
fauna, chiefly those of Dr. A. Ulrich,* it has been shown that the 
east American Middle Devonian fauna is related to the South 
American fauna. The peculiar genera 7vopidoleptus and Vitulina 
are characteristic of these two regions, being unknown in the 
European and west American Devonian faunas. Besides these 
genera, there are other bonds of relationship between the 
faunas. This east American fauna inhabited an area bounded on 
the north by the nucleus of the North American continent and 
on the east by the land area lying at that time to the east of the 
present Appalachian region. It did not extend westward beyond 
the Mississippi River. From its relationship to the South Amer- 
ican faunas, we may conclude that it extended far to the south. 
The contemporaneous European fauna was largely developed 
in central Europe, in the Ural Mountain region, and extended 
across Asia and into the western part of North America. In 
America its most typical development was in the far northwest. 
It was first described by Meek? from the Mackenzie River basin, 
and has lately been much more completely described by Whit- 
eaves It extends southeastwardly, and, in the so-called Ham- 
ilton of Iowa, it reached the Mississippi River. 
Distribution of land and water during Devonian time —In 
seeking for the barrier, which must have existed during the 
greater part of Devonian time, near the present location of 
the Mississippi River, the presence of a land barrier seems to be 
necessarily presupposed. The stratigraphy of the region admits 
of this conclusion. Along the southern border of the Silurian 
peninsula, extending southward and including a large part of 
« Beitrage zur Geol. und Pal. von Siidamerika, I, Palaozoische Versteinerungen 
aus Bolivien. 
2 Trans. Chic. Acad. Sci., Vol. I. (1868). 
3 Cont. to Canadian Pal., Vol.I., Part ILI. (1891). 
