Chap. XI. 
GEOGRAPHICAL DISTRIBUTION-. 
349 
and the eastern shores of Africa, on almost exactly oppo¬ 
site meridians of longitude. 
A third great fact, partly included in the foregoing 
statements, is the afiSnity of the productions of the 
same continent or sea, though the species themselves 
are distinct at different points and stations. It is 
a law of the widest generality, and every continent 
offers innumerable instances. Nevertheless the natu¬ 
ralist in travelling, for instance, from north to south 
never fails to be struck by the manner in which suc¬ 
cessive groups of beings, specifically distinct, yet clearly 
related, replace each other. He hears ^from closely 
allied, yet distinct kinds of birds, notes nearly similar, 
and sees their nests similarly constructed, but not quite 
alike, with eggs coloured in nearly the same manner. 
The plains near the Straits of Magellan are inhabited 
by one species of Ehea (American ostrich), and north¬ 
ward the plains of La Plata by another species of the 
same genus; and not by a true ostrich or emu, like 
those found in Africa and Australia under the same 
latitude. On these same plains of La Plata, we see 
the agouti and bizcacha, animals having nearly the 
same habits as our hares and rabbits and belonging to 
the same order of Eodents, but they plainly display 
an American type of structure. We ascend the lofty 
peaks of the Cordillera and we find an alpine species 
of bizcacha ; we look to the waters, and we do not find 
the beaver or musk-rat, but the coypu and capybara, 
rodents of the American type. Innumerable other in¬ 
stances could be given. If we look to the islands off 
the American shore, however much they may differ in 
geological structure, the inhabitants, though they may 
be all peculiar species, are essentially American. We 
may look back to past ages, as shown in the last 
chapter, and we find American types then prevalent on 
