53o POPULAR SCIENCE MONTHLY 



Andes east of Guayaquil before the Andes reached their present height. 

 The Pacific slope fauna is less different from the Amazon fauna than 

 that of the coastwise streams of Minas, if the number of peculiar 

 genera is used as a measure of difference. The origin of the fauna of 

 the plateau of Mexico is a separate subject. 



The points of strategic importance for ichthyic chorology in South 

 America are, therefore: (a) western Colombia and Panama; (&) Guay- 

 aquil to the Amazon, across the Andes; (c) the tableland of Guiana, 

 Archiguiana; (d) the Eio San Francisco, with the Ria Parahyba and 

 the headwaters of the Tiete and Rio Grande, in Archamazona; and 

 (e) the area between the Rio Negro and the La Plata. It is these 

 regions which will yield the richest scientific harvest to any museum 

 undertaking South American exploration. 



