130 ST. FE. [chap, vn 



Ehrenberg has had the kindness to examine for me a little of the 

 red earth, taken from low down in the deposit, close to the 

 skeletons of the mastodon, and he finds in it many infusoria, 

 partly salt-water and partly fresh-water forms, with the latter 

 rather preponderating- ; and therefore, as he remarks, the water 

 must have been brackish. M. A. d'Orbigny found on the banks 

 of the Parana, at the height of a hundred feet, great beds of an 

 estuary shell, now living a hundred miles lower down nearer the 

 sea ; and I found similar shells at a less height on the banks of 

 the Uruguay : this shows that just before the Pampas was slowly 

 elevated into dry land, the water covering it was brackish. 

 Below Buenos Ayres there are upraised beds of sea-shells of 

 existing species, which also proves that the period of elevation 

 of the Pampas was within the recent period. 



In the Pampsean deposit at theBajadal found the osseous armour 

 of a gigantic armadillo-like animal, the inside of which, when the 

 earth was removed, was like a great cauldron ; I found also teeth of 

 the Toxodon and Mastodon, and one tooth of a Horse, in the same 

 stained and decayed state. This latter tooth greatly interested 

 me,* and I took scrupulous care in ascertaining that it had been 

 embedded contemporaneously with the other remains ; for I was 

 not then aware that amongst the fossils from Bahia Blanca there 

 was a horse's tooth hidden in the matrix : nor was it then known 

 with certainty that the remains of horses are common in North 

 America. Mr. Lyell has lately brought from the United States 

 a tooth of a horse ; and it is an interesting fact, that Professor 

 Owen could find in no species, either fossil or recent, a slight 

 but peculiar curvature characterizing it, until he thought of com- 

 paring it with my specimen found here : he has named this 

 American horse Equus curvidens. Certainly it is a marvellous 

 fact in the history of the Mammalia, that in South America a 

 native horse should have lived and disappeared, to be succeeded 

 in after ages by the countless herds descended from the few 

 introduced with the Spanish colonists ! 



The existence in South America of a fossil horse, of the 

 mastodon, possibly of an elephant,! and of a hollow-horned 



* I need hardly state here that there is good evidence against any horse 

 living in America at the time of Columbus, 

 f Cuvier. Osseins Fossiles, torn. i. p. 158. 





