nd thereby
give rise to a strong tendency to move parallel to their bases. During
the days of primitive man the trend of the mountains apparently directed
his migrations northeastward to Bering Strait and then southeastward
and southward from one end of America to the other. In the same way the
migrations to Europe and Africa which ultimately reached America moved
mainly parallel to the mountains.

From end to end of America the great mountains form a sharp dividing
line. The aboriginal tribes on the Pacific slope are markedly different
from those farther east across the mountains. Brinton sums the case up
admirably:

"As a rule the tribes of the western coast are not connected with any
east of the mountains. What is more singular, although they
differ surprisingly among themselves in language, they have marked
anthropologic similarities, physical and psychical. Virchow has
emphasized the fact that the skulls from the northern point of
Vancouver's Island reveal an unmistakable analogy to those from the
southern coast of California; and this is to a degree true of many
intermediate points. Not that the crania have the same indices. On the
contrary, they present great and constant differences within the same
tribe; but these differences are analogous one to the other, and on
fixed lines.

"There are many other physical similarities which mark the Pacific
Indians and contrast them with those east of the mountains. The eyes are
less oblique, the nose flatter, the lips fuller, the chin more pointed,
the face wider. There is more hair on the face and in the axilla, and
the difference between the sexes is much more obvious.

"The mental character is also in contrast. The Pacific tribes are more
quiet, submissive, and docile; they have less courage, and less of that
untamable independence which is so constant a feature in the history of
the Algonquins and Iroquois." *

* D. G. Brinton, "The American Race," pp. 103-4.

Although mountains may guide migrations, the plains are the regions
where people dwell in greatest numbers. The plains in the two great land
masses of the Old World and the New have the same inverse or right- and
left-handed symmetry as the mountains. In the north the vast stretches
from the Mackenzie River to the Gulf of Mexico correspond to the plains
of Siberia and Russia from the Lena to the Black Sea. Both regions have
a vast sweep of monotonous tundras at the north and both become fertile
gra