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Indiana University Studies 



only very small dugouts can make the whole distance to Tainbo, 

 near the divide. On the Pacific slope dugouts make the trip 

 from Condoto and Istmina, without difficulty, to Puerto Negria. 

 Small steamers ascend to Puerto Negria. 



The coastal Cordilleras 5 west of the Atrato and San Juan are 

 said to be quarternary. If so, the valley of the Atrato-San Juan 

 has but recently been open ocean. The height of land separating 

 the Atrato and San Juan is said to have been pierced by a canal 

 near Kaspadura by the Bishop Raspadura. If so, nothing re- 

 mains of it except possibly that Astyanax fasciatus, abund- 

 ant on the Atlantic side, is sparingly found near the Pacific side 

 of the reported location of the canal. 



To what extent, if any, have the Atrato and San Juan been 

 used as a highway for the intermigration of fresh-water fishes ? 



The Fishes of the Atrato. Lieutenant Schott, of the Michler 

 expedition noted above, collected in the Rio Truando, a western 

 tributary of the lower Atrato. The following letter of Gill refers 

 to this collection. 



The letter {I.e. pp. 257-259) gives a general report on all the 

 fishes collected during Michler's expedition. A detailed list was 

 never published. The fishes collected were evidently largely ma- 

 rine, probably from the Gulf of Uraba. The letter, omitting the 

 parts pertaining to the strictly marine fishes, follows : 



Smithsonian Institution, 

 Washington, D.C., 



January 14, 1861. 



Dear Sir : 



I have made a cursory examination of the collection, and I find that 

 there are some interesting forms. Desirous of obliging you, I will furnish 

 a list of the genera to which the species belong. 



Of the Teleocephalous fishes, representatives of nineteen genera are pres- 

 ent in the collection. They belong to the families enumerated below. 



Of the family of Percoids there are three species, which belong to as 

 many different genera and subfamilies. 



There is one specimen of the genus Centropomus of Lacepede, a member 

 of the subfamily of Percinae. 



5 The crest of these Cordilleras runs near the Pacific, being in some places only a 

 few hundred feet from the ocean. The western side is very steep, the eastern slope 

 is more gradual, and is separated from the Atrato by a wide lowland. There is a 

 modification of this arrangement where the Rio Baudo flows between two ranges 

 of the coast Cordilleras. 



