CHAPTER VII 
THE CONTINENTAL BASIN 
Bounded in the east by what might collectively be termed 
the Atlantic Mountains and in the west by the Pacific Moun¬ 
tain system lies the immense continental basin. It is open 
to the sea both in the north and south, extending in one 
continuous series of plains and plateaux from the Gulf of 
Mexico to the Arctic Ocean. The northern portion of this 
great interior basin has already been briefly described in the 
second and third chapters. The rivers of this part of the 
continent drain eastward to the Atlantic Ocean and northward 
to Hudson Bay and the Arctic Ocean. The drainage of the 
southern portion is supplied almost entirely by the Missis¬ 
sippi, and is thus discharged into the Gulf of Mexico. It is 
this southern section of North America and its fauna with 
which I propose to deal very briefly in this chapter. 
The low-lying and gently seaward-sloping belt of land 
bordering the Gulf of Mexico is known as the “ gulf plains.” 
It is here in this rich soil that sugar-cane, cotton and rice are 
cultivated. The west-central part of the continental basin 
is occupied by the “ prairie plains.” By the term “ prairie ” 
we recognise a level region, either a plain or a plateau, with¬ 
out forests, but clothed in a carpet of luxuriant grasses and 
flowering annuals. On their eastern and northern border 
these prairie plains merge into the adjacent forested plains, 
while in the west they gradually pass into the more elevated 
and drier high plains, where bunch grass, with bare intervals 
between the scattered tufts, takes the place of the continuous 
sod of the true prairies. 
There is a widespread popular belief in Europe that the 
whole of the vast American continental basin is one extensive 
prairie or pasture land. This is quite a mistake. As we 
approach the Mississippi River from the west wo gradually 
