70 RIO COLORADO. [chap. iv. 



that genus in many essential respects ; for instance, it lias only 

 three toes behind. It is also nearly twice the size, weighing 

 from twenty to twenty-five pounds. The Agouti is a true friend 

 of the desert ; it is a common feature in the landscape to see two 

 or three hopping quickly one after the other in a straight line 

 across these wild plains. They are found as far north as the 

 Sierra Tapalguen (lat. 37° 30'), where the plain rather suddenly 

 becomes greener and more humid ; and their southern limit is 

 between Port Desire and St. Julian, where there is no change in 

 the nature of the country. It is a singular fact, that although 

 the Agouti is not now found as far south as Port St. Julian, yet 

 that Captain Wood, in his voyage in 1670, talks of them as 

 being numerous there. What cause can have altered, in a wide, 

 uninhabited, and rarely- visited country, the range of an animal 

 like this? It appears also from the number shot by Captain 

 Wood in one day at Port Desire, that they must have been 

 considerably more abundant there formerly than at present. 

 Where the Bizcacha lives and makes its burrows, the Agouti 

 uses them; but where, as at Bahia Blanca, the Bizcacha is 

 not found, the Agouti burrows for itself. The same thing 

 occurs with the little owl of the Pampas (Athene cunicularia), 

 which has so often been described as standing like a sentinel 

 at the mouth of the burrows ; for in Banda Oriental, owing to 

 the absence of the Bizcacha, it is obliged to hollow out its own 

 habitation. 



The next morning, as we approached the Rio Colorado, the 

 appearance of the country changed ; we soon came on a plain 

 covered with turf, which, from its flowers, tall clover, and little 

 owls, resembled the Pampas. We passed also a muddy swamp 

 of considerable extent, which in summer dries, and becomes in- 

 crusted with various salts; and hence is called a salitral. It was 

 covered by low succulent plants, of the same kind with those 

 growing on the sea-shore. The Colorado, at the pass where we 

 crossed it, is only about sixty yards wide ; generally it must be 

 nearly double that width. Its course is very tortuous, being 

 marked by willow-trees and beds of reeds : in a direct line the 

 distance to the mouth of the i iver is said to be nine leagues, but 

 by water twenty-five. We were delayed crossing in the canoe 

 by some immense troops of mares, which were swimming the 



