396 
ORIGIN OF LIFE IN AMERICA 
we proceed southward, the fauna and flora gradually undergo 
a complete change. On leaving the forest, monkeys, sloths 
and other animals, bound to an arboreal life, are replaced by 
new types, unknown in Brazil, such as the Patagonian hare 
and vizcacha. A very characteristic faunistic feature of the 
Argentine “ pampas,” as the humid grassy country is called, 
is the presence there of the American representative of the 
ostrich. This rhea is quite absent from the vast forests of 
Brazil. In the northern parts of that country, however, where 
we again meet with grass lands, this flightless bird reappears 
as a memento of the times when north and south were joined 
by continuous prairies. We thus have some noteworthy 
instances of discontinuous distribution suggesting a former 
period when the drying up of vast lakes, perhaps, may have 
given rise to grass lands, which enabled certain southern types 
to push northward. Other Argentine animals, such as the 
coypu (Myocastor coypus), one of the largest of the rodent 
tribe, have apparently invaded Brazil in more recent times, 
for they have only entered the southern and western pro¬ 
vinces. To those unacquainted with the past history of South 
America it must come as a matter of surprise that the only 
ungulate which is noticed in these vast pampas of Argen¬ 
tina is a deer, closely related to the true North American deer 
(Odocoileus virginianus) and its allies. I have expressed my 
belief above (p. Ill) that the true American deer owe their 
origin to one or more ancestors which passed into South 
America directly from Europe, and it is important to note 
that the centre of dispersal of the various groups in South 
America lies in the western states. Only a couple of species 
are peculiar to Brazil. All the others are more or less 
confined to the western states. Even the distribution of the 
South American wolves led Dr. von Ihering * to the similar 
conclusion that these animals entered the continent from the 
west. 
Mr. W. H. Hudson f gives us a vivid idea of the life in the 
pampas of Argentina, the striking poverty of its fauna as 
compared with Brazil, and all the more characteristic features 
* Ihering, H. von, “ Siidamerikanische Baubtiere,” p. 162. 
t Hudson, W. II., “ Naturalist in La Plata.” 
