EIGENMANN: the freshwater fishes of BRITISH GUIANA 



101 



Fig. 23. Table showing Distribution of the Fishes taken by C. H. Eigenmann in the Potaro River above 

 the Kaieteur Falls. (No. 18a, mentioned in the table above, should have been added. It was overlooked 

 in preparing this figure.) 



great improbability that so many species should have retained their identity since 

 the early tertiary, or should have diverged only in minor specific characters, dis- 

 poses of the theory that this fauna as a whole is the nucleus of the original South 

 American fauna. The number of species peculiar to the plateau forms a larger 

 percentage than a corresponding list for the entire Potaro below the Kaieteur, but 

 not too large to be readilj' accounted for by the easy access to the Lower Potaro pos- 

 sessed by all the species of the Essequibo. Such easy access tends to lower the per- 

 centage of uniques. 



The percentage of peculiar species above the Potaro Landing is about the same 

 as for the plateau, and in actual numbers almost equal to the entire fauna of the 

 plateau. 



