356 
BASIN OF THE GULF OF MEXICO. 
the Eed Elver of Nachitoches, so that the northern part onlv 
of the state of Illinois is covered with gramina. This line 
of demarcation is not only interesting for the geography 
of plants, but exerts, as we have said above, great influence 
in retarding culture and population north-west of the Lower 
Mississippi. In the ITnited States, the prairie countries 
are more slowly colonized ; and even the tribes of independent 
Indians are forced by the rigour of the climate to pass the 
winter on the banks of rivers, where poplars and willows 
are found. The basins of the Mississippi, of the lakes of 
Canada and the 8t. Lawrence, are the largest in America; 
and though the total population does not rise at present 
beyond three millions, it may be considered as that in 
which, between latitude 29° and 45° (long. 74° — 94°), civili- 
zation has made the greatest progress. It may even be said 
that in the other basins (of the Orinoco, the Amazon, and 
Buenos Ayres), agricultural life scarcely exists ; it begins, on 
a small number of points only, to supersede pastoral life, and 
that of fishing and hunting nations. The plains between the 
Alleghanies and the Andes of Upper Louisiana are of such 
vast extent, that like the Pampas of Choco and Buenos 
Ayres, bamboos (Ludolfia miega) and palm-trees grow at one 
extremity, while the other, during a great part of the year, 
is covered with ice and snow. 
II. — The basin of the Gulf of Mexico, and of thf. 
Cabtbbean Sea. This is a continuation of the basin of the 
IMississippi, Louisiana, and Hudson’s B.ay. It may be said, 
that all the low lauds on tho coast of Venezuela situated 
north of tlie littoral chain, and of the Sierra Xevada de 
Merida, belong to the submerged part of this basin. If I 
treat here separately of the basin of the Caribbean Sea, it is 
to avoid conloundiug what, in the present state of the globe, 
is partly above and partly below the ocean. The recent 
coincidence of the periods of earthquakes observed at Caracas, 
and on the banks of the Mississippi, the Arkansas, and the 
Ohio, justifies the geologic theories which regard as one 
basin the plains bounded on the soutli, by tlie littoral Cor- 
dillera of Venezuela; on the east, by the Alleghanies .and 
the series of the vo-lcanos of the West Indies; and on the 
west, by the Eocky Mountains (Mexican Andes) and by the 
