HNMPOTHE SIS OF. CAUSE OF GLACTAL! PERIODS” 783 
westward connections. In other words, the somewhat balanced 
distribution of the present Pacific was replaced by an effective 
obliquity which could scarcely have failed to powerfully influ- 
ence the general circulation of the Paleozoic atmosphere. The 
northwest-southeasterly extension of the great Eurasian-Austra- 
lian land paralleled this and intensified its effects. In other 
words, the Pacific Ocean and the parallel Eurasian-Australian 
continent constituted, in Paleozoic times, a couplet of oblique 
features that were chiefly effective in the equatorial zone and 
the southern hemisphere. They replaced the similar pair now 
formed by the north Atlantic and the eastern continent. It is 
inferred, therefore, that an obliquity of circulation of a pro- 
nounced order prevailed in Permo-Carboniferous times, by virtue 
of which the southern hemisphere was brought under the influence 
of meteorological agencies analogous to those that in Pleistocene 
times affected the northern hemisphere. 
Some differences, however, are to be noted. The equatorial 
zone was then profoundly affected by the oblique features which 
lay directly athwart it. In addition to this there was the pecul- 
lar configuration of the Indian Ocean already set forth, namely, 
a broad, open mouth extended to the Antarctic polar regions, 
with a convergence to a narrow equatorial apex 20° or more 
north of the equator. The general course of the circulation in 
this may be assumed to have been much as it is today; that is, 
a movement in the polar latitudes, at first northerly and easterly, 
then curving about to the northward and northwestward as it 
approached the equatorial zone, and at length returning to the 
southwest along the African coast, thus forming a free circula- 
tion between the high latitudes and the low latitudes, with high 
latitude influences greatly preponderant. This circulation in 
Paleozoic times may be reasonably assumed to have been much 
more intense than at the present time, first, because there were 
then, by hypothesis, greater intensities of temperature, and 
second, because a larger percentage of the Antarctic waters were 
forced to flow into the apex of the Indian Ocean by the con- 
figuration of the land. This last statement would hold true even 
