XV 
VIEW OF THE PAMPAS 
349 
I obtained thirteen species on the shores of the Atlantic, and 
five on the Pacific, and not one of them is identical. We must 
except all those species which habitually or occasionally frequent 
elevated mountains ; and certain birds, which range as far south 
as the Strait of Magellan. This fact is in perfect accordance 
with the geological history of the Andes ; for these mountains 
have existed as a great barrier, since the present races of 
animals have appeared ; and therefore, unless we suppose the 
same species to have been created in two different places, we 
ought not to expect any closer similarity between the organic 
beings on the opposite sides of the Andes, than on the opposite 
shores of the ocean. In both cases we must leave out of the 
question those kinds which have been able to cross the barrier, 
whether of solid rock or salt water. 1 
A great number of the plants and animals were absolutely 
the same as, or most closely allied to, those of Patagonia. We 
here have the agouti, bizcacha, three species of armadillo, the 
ostrich, certain kinds of partridges and other birds, none of 
which are ever seen in Chile, but are the characteristic animals 
of the desert plains of Patagonia. We have likewise many of 
the same (to the eyes of a person who is not a botanist) thorny 
stunted bushes, withered grass, and dwarf plants. Even the 
black slowly-crawling beetles are closely similar, and some, I 
believe, on rigorous examination, absolutely identical. It had 
always been to me a subject of regret that we were unavoidably 
compelled to give up the ascent of the S. Cruz river before 
reaching the mountains : I always had a latent hope of meeting 
with some great change in the features of the country ; but I 
now feel sure that it would only have been following the plains 
of Patagonia up a mountainous ascent. 
March 24 th .— Early in the morning I climbed up a moun¬ 
tain on one side of the valley, and enjoyed a far-extended view 
over the Pampas. This was a spectacle to which I had always 
looked forward with interest, but I was disappointed : at the 
first glance it much resembled a distant view of the ocean, but 
in the northern parts many irregularities were soon distinguish- 
1 This is merely an illustration of the admirable laws, first laid down by Mr. 
Lyell, on the geographical distribution of animals, as influenced by geological changes. 
The whole reasoning, of course, is founded on the assumption of the immutability of 
species; otherwise the difference in the species in the two regions might be con¬ 
sidered as superinduced during a length of time. 
