MAY, 1902. THE ICHTHYOLOGY OF MEXICO MEEK. 127 



still enough has been done to indicate the fact that it contains 

 comparatively few species of fishes. 



The Rio Verde, a small stream considerably south and east of 

 the Rio Balsas, was examined at Oaxaca, and only two species 

 of fishes, Heterandia lutzi and Fundulus oaxaca, were taken from 

 it; neither of these are found in the Balsas. 



The Rio Quiotepec has two species of fishes in common with 

 the Rio Balsas, Tetragonopterus mexicanus and Agonostomus nasu- 

 tus. The latter species, together with Pacilia limantouri, is also 

 found in the Rio Balsas and the Rio San Francisco at La Antigua. 

 The rivers south of Mexico City on both sides of the divide have 

 much more in common as to their faunas, than any of them have 

 with the Valley of Mexico and the Lerma. 



Evermann andGoldsborough call attention to some small dried 

 specimens of fishes purchased in the markets of Yautepec, More- 

 los. These specimens appear to be Chirostoma jordani. It is 

 likely these fishes were sent to these markets from Mexico City 

 or some point in the Lerma Basin. I do not believe they were 

 obtained in the Balsas Basin. 



The Leuciscus nigrescens recorded by B. A. Bean from Lago de 

 Quitzeo, has since been identified by him as Algansea tincella. 

 There is some doubt as to whether the type of Algansea sallei 

 really came from Cuernavaca. Neither Jordan, Snyder nor myself 

 found any species of this genus in the Rio Balsas Basin; and from 

 the fact that the faunas of the Rio Lerma and Rio Balsas are so 

 unlike, I doubt if this species occurs in the latter. 



Tetragonopterus mexicanus is, I believe, wrongly ascribed by 

 Fillipe to the Valley of Mexico. Mr. Woolman records Campos- 

 toma ornatum from Salamanco in the Lerma Basin. It is likely 

 his specimen really came from Chihuahua. 



SUMMARY. 



The fish fauna of northern Mexico is essentially that of the 

 Rocky Mountains and Eastern United States, or that part of the 

 United States adjacent to Mexico. The Eastern fauna has 

 crowded its way over the divide and has become even more firmly 

 established in the Pacific coast streams of Sonora than has the 

 Rocky Mountain fauna. 



The South and Central American faunas prevail largely as far 

 north as the City of Mexico. The few forms which extend farther 



