12 ANNALS NEW YORK ACADEMY OF .SCIENCES 



It is in the first part of this thesis that my effort will be to demon- 

 strate on geological grounds that South America has not been connected 

 with the eastern hemisphere. In this connection, I have also been able 

 to map for the first time the outline of the Piano Alto (the highlands of 

 South America) which was deposited by the wind and rivers in a dry 

 land and fresh-water basin which I am calling the Permian Inland Basin. 

 This highland, I propose to show, was of the utmost continental impor- 

 tance, from its dip, its lack of Mesozoic and Tertiary marine deposits and 

 the direction of the trend lines, taken in connection with the Tertiary rise 

 of the Andes ; in fact, upon this I shall base my doctrine that the Amazon 

 is a reversed river whose headwaters originally flowed into what I have 

 designated the East Andean Sea. 



This outlining of the Piano Alto is of prime importance, not only be- 

 cause it has given me the key to the correct explanation of the distribu- 

 tion of the aquatic life, but also because it shows that South America has 

 not been cut into islands by east and west invasions of the sea as has 

 been proposed by some of the exponents of the Archhelenis theory of 

 von Ihering. 



In other topographical matters which are of importance from the 

 zoogeographical viewpoint, I will also show that the Paraguay Eiver is 

 not connected with the Guapore, as has been so often erroneously stated, 

 and that Eio Sao Francisco is connected with Eio Tocantins. I will 

 note additional cases of stream piracy and will show that these taken in 

 connection with waterfalls, swamps and certain environmental conditions 

 will aid us in interpreting with a certain degree of accuracy questions in 

 the distribution of the South American fishes. 



In the last part of this thesis, an attempt will be made to demonstrate 

 that the fauna of South America has been evolved from the forms which 

 originally lived in North America. In arriving at this conclusion, I 

 have not entirely limited my studies to the fishes, but I have considered 

 carefully the voluminous data derived from other groups of living and 

 extinct animals and plants which have been used to establish connections 

 between South America and the eastern hemisphere. I have considered 

 all of these data, because the facts derived from the distribution of any 

 one group of plants or animals are not sufficient alone to warrant an in- 

 terpretation which involves profound modifications of the earth's surface 

 as maintained by many authors. 



In the matter of the distribution of fishes, as bearing upon the greater 

 problem, my effort will be to show 



1. That the present distribution of fishes gives no clue to the point of 

 origin of the families, but it does for some of the genera and many species. 



2. The point of family origin can only be determined after the living 



