358 Louis Agassiz on the Natural 
southern United States, and a Californian fauna, the characteristic 
features of which I shall describe on another occasion. 
When we consider, however, the isolation. of the American con- 
tinent from those of the Old World, nothing is more striking in the 
geographical distribution of animals, than the exact correspondence of 
all the animals of the northern temperate zone of America with those 
of Europe; all the characteristic forms of which, as may be seen by the 
fourth column of our table, belong to the same genera, with the ex- 
ception of a few subordinate types, not represented among our 
firures—such as the opossum and the skunk, 
In tropical America we may distinguish a Central American 
fauna, a Brazilian fauna, a fauna of the Pampas, a fauna of the 
Cordilleras, a Peruvian fauna, and a Patagonian fauna ; but it 
is unnecessary for our purpose to mention here their characteristic 
features, which may be gathered from the works of Prince New 
Wied, of Spix and Martius, of Tschudi, of Poppig, of Ramon de 
la Sagra, of Darwin, &c. 
The slight differences existing between the faunz of the tem- 
perate zone have required a fuller illustration than may be necessary 
to characterize the zoological realms of the tropical regions, and the 
southern hemisphere generally. It is sufficient for our purpose to 
say here, that these realms are at once distinguished by the pre- 
valence of peculiar types, circumscribed within the natural limits of 
the three continents, extending in complete isolation towards the 
southern pole. In this respect there is already a striking contrast 
between the northern and the southern hemisphere. But the more 
closely we compare them with one another, the greater appear their 
differences. We have already seen how South America differs 
from Africa, the East Indies, and Australia, by its closer con- 
nection with North America. Notwithstanding, however, the ab- 
sence in South America of those sightly animals so prominent in 
Africa and tropical Asia, its general character is, like that of all 
the tropical continents, to nourish a variety of types which have no 
close relations to those of other continents. Its monkeys and eden- 
tata belong to genera which have no representatives in the Old 
World. Among pachyderms, it has peccaries, which are entirely 
wanting elsewhere ; and though the tapirs occur alsoan the Sunda 
Islands, that type is wanting in Africa, where, in compensation, we 
find the hippopotamus, not found in either Asia or America. We 
have already seen that the marsupials of South America differ en- 
tirely from those of Australia. Its ostriches differ also generally 
from those of Africa, tropical Asia, New Holland, &c. 
If we compare, further, the southern continents of the Old World 
with one another, we find a certain uniformity between the animals 
of Africa and tropical Asia. They have both elephants and rhino- 
ceroses, though each has its peculiar species of these genera, which 
occur neither in America nor in Australia; whilst cercopitheci and 
7) 
