270 STUART WELLER 
The path of communication between the Eastern Continental 
Province, in Onondaga time, and the Western Continental Province 
must have been indirect, although there was certainly some community 
of origin of the faunas in the two regions. If the northern origin of the 
Onondaga fauna, as has been suggested by the writer,’ has sufficient 
foundation, which is perhaps doubtful, the fauna may have migrated 
southward into two epicontinental embayments, one into the Eastern 
Continental Province, by way of Hudson Bay and James Bay, and 
another farther west into the Western Continental Province. The 
mingling of the Onondaga and the Iowan faunas might be accounted 
for on this basis, since it is quite definitely recognized that the latter 
fauna has a northwestern origin, at least in so far as North America is 
concerned. One objection to this view is the fact that the Onondaga 
fauna is not represented among the known faunas from the Mackenzie 
Basin, although there is sufficient room for its occurrence in some of 
the older Devonian beds of that region which have not yet afforded 
any fauna. A southern pathway of communication between the two 
provinces is a possibility, although on such an hypothesis the absence 
of the southern hemisphere element of the later Middle Devonian 
faunas of the East is not easy to account for. 
THE NORTH AMERICAN MISSISSIPPIAN PROVINCES 
The early stages of the Mississippian period were marked by a 
continuation of the transgression of the sea in the south and south- 
western part of the Eastern Continental Province, which had been 
initiated during Upper Devonian time, but it was extended also to the 
northwest. Before the close of the Kinderhook epoch, the sea had 
crossed the Kankakee peninsula and had surrounded the Ozark land 
which became an island or was perhaps entirely submerged, and 
had stretched away toward the Rocky Mountain land, so that the 
earlier Eastern Continental and Interior Continental provinces were 
merged into one great interior province with three subordinate basins 
or subprovinces, (1) the Appalachain Basin lying between Appalachia 
and the Cincinnati arch and extending from Michigan to Alabama, 
(2) the Mississippi Valley basin extending westward from the Cincin- 
nati arch and merging with the Appalachian Basin to the south, (3) 
t Jour. Geol., X, 4209. 
