III. ON THE RESEMBLANCE BETWEEN THE FAUNAS 

 OF TRANSANDEAN COLOMBIA AND SOUTH- 

 EASTERN TROPICAL AMERICA 



One group of genera of the Glandulocaudinse, Pterobrycon, 

 Gephyrocharaix and Sf&vardda, is found in northwestern South 

 America, the first two being, as far as known, found west of the 

 Eastern Cordilleras of Colombia. The remaining genera are found 

 at the opposite corner of the tropical region of South America; 

 that is to say, in southeastern Brazil and Uruguay. If they are 

 found between these two regions they have so far not been ob- 

 served there. 



The distribution of the Glandulocaudinse indicates similar phys- 

 ical conditions or similar origin for the faunas of transandean 

 Colombia and Southeastern tropical South America. 



Of like import is the distribution of the genus Salminus. One 

 species is found west of the Eastern Cordilleras of Colombia and 

 the other one is found in the La Plata basin. A somewhat similar 

 condition is found in the distribution of the genera Pseudochalceus 

 from western Ecuador and its nearest relative HoUatndichthys from 

 southeastern Brazil. Furthermore, the genus Bryco'tmmericus 

 finds its greatest development along the Cordilleras of Ecuador 

 and Colombia and in the La Plata basin to Rio Grande do Sul. 

 Similarly, the species Asiyanax fasciatics reaches its greatest de- 

 velopment and has diverged into the largest number of varieties 

 west of the Eastern Cordilleras of Colombia and in southeastern 

 Brazil, 



There is evidence that the similarity between the faunas of 

 the region west of the Eastern Cordilleras of Colombia and the 

 southeastern corner of the tropical regions of South America is 

 not confined to positive resemblances, but that a number of types 

 absent from northwestern Colombia are also absent from south- 

 eastern Brazil to Buenos Aires. The details in the distribution 

 will be pointed out later. 



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