1835.] VIEW OF THE PAMPAS. 327 
geological history of the Andes; for these mountains have ex- 
isted 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.* 
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 24th.—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- 
able. The most striking feature consisted in the rivers, which, 
facing the rising sun, glittered like silver threads, till lost in the 
immensity of the distance. At midday we descended the valley, 
* This is merely an illustration of the admirable laws, first laid down by 
Mr. Lyell, on the geographical distribution of animals, as influenced by geo- 
logical changes. ‘The whole reasoning, of course, is founded on the assump- 
tion of the immutability of species; otherwise the difference in the species 
in the two regions, might he considered as superinduced during a length of 
time. 
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