34 LAND MAMMALS IN THE WESTERN HEMISPHERE 



rain fell, that the vegetation, even to the thistles, failed ; 

 the brooks were dried up, and the whole country assumed the 

 appearance of a dusty high road." ''I was informed by an 

 eyewitness that the cattle in herds of thousands rushed into 

 the Parana, and being exhausted by hunger they were unable 

 to crawl up the muddy banks, and thus were drowned. The 

 arm of the river which runs by San Pedro was so full of putrid 

 carcasses, that the master of a vessel told me that the smell 

 rendered it quite impassable. Without doubt several hundred 

 thousand animals thus perished in the river; their bodies 

 when putrid were seen floating down the stream ; and many in 

 all probability were deposited in the estuary of the Plata. All 

 the small rivers became highly saline, and this caused the death 

 of vast numbers in particular spots ; for when an animal 

 drinks of such water it does not recover. Azara describes the 

 fury of the wild horses on a similar occasion, rushing into the 

 marshes, those which arrived first being overwhelmed and 

 crushed by those which followed. He adds that more than 

 once he has seen the carcasses of upwards of a thousand wild 

 horses thus destroyed. . . . Subsequently to the drought of 

 1827 to 1832, a very rainy season followed, which caused great 

 floods. Hence it is almost certain that some thousands of 

 the skeletons were buried by the deposits of the very next 

 year." ^ 



In the arid and desolate regions of the interior of South 

 Australia is a series of immense dry lakes, which only occasionally 

 contain water and ordinarily ''are shallow, mud-bottomed or 

 salt-encrusted claypans only." One of these, Lake Calla- 

 bonna, is of great interest as having preserved in its soft mud 

 many remains of ancient life, of creatures which were mired 

 in the clay and destroyed, as has been described by Dr. E. C. 

 Stirling. ''There is, however, compensation for the unpromis- 

 ing physical features of Lake Callabonna in the fact that its 

 bed proves to be a veritable necropolis of gigantic extinct 

 1 Voyage of a Naturalist, Amer. ed., pp. 133-134. 



