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 

 apj)eared ; 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 

 b'jlieve, on rigorous examination, absolutely -identical. It had 

 alwaj's 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.ou 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 specit's ; otherwise the difference in the species 

 in the two regions, might be considered as superinduced during a length of 

 time. 



15 



