520 



POPULAR SCIENCE MONTHLY 



6. liatystomalichthys slurio Kner, One of the Giant Catfishes. 



7. A New Piecostomus, One of the Mailed Catfishes. 



8. A Farlowella, One of the Slenderest of the Mailed Catfishes. 



4. The Isolation of the Fauna of the Mexican Plateau. 



The Lerma, draining the Mexican plateau, harbors an old fauna. 

 Only three of its fifty-four species have been taken in any other river 

 basin. Eight of its twenty-one genera are peculiar to it. 



5. Paucity of the Pacific Slope Fauna. 



From the Pacific slope of South America, south of Panama and 

 north of Chile, but 55 species of fresh-water fishes have been reported. 

 This condition is not unlike the condition in North America, for more 

 species may be obtained from a single favorable brook in the Mississippi 

 valley than are found on our entire Pacific slope, from San Diego to 

 Alaska. 



Fifteen out of the 55 species are also found on the Atlantic slope, 

 and the others, with three exceptions, belong to genera of wide distribu- 

 tion on the Atlantic slope. None of the species would cause any sur- 

 prise if found on the Atlantic slope. 



