PACIFIC SLOPE OF ECUADOR, PERU AND CHILI. 509 



species may be it is certainly of northern origin. Regan identifies 

 some specimens from Ecuador as Bryconamericus scleroparius, a 

 Costa Rican species. 



Microglanis, Paracetopsis, Leporinus, Prochilodus, and possibly 

 Curimatus, indicate that the ancestors of the Guayas fishes came 

 from the east. Microglanis is found east of the Andes but not in 

 Colombia. Paracctopsis has its nearest relative in the Amazon, not 

 in the north. Plecostomus, Ancistrusf, Apareiodonf, Leporinus and 

 Procliilodus are found both in the Amazon and in Colombia but 

 there is a hiatus in their distribution reaching from the San Juan 

 to the Esmeraldas. They probably came independently into the 

 Magdalena and into the Guayas. While Curimatus ranges every- 

 where in Colombia, the Ecuadorian species are very distinct from 

 Curimatus Uneapunctatus and its variety patice, the only ones in the 

 region between the Atrato and the Esmeraldas. Curimatus came 

 independently into the Magdalena and into the Guayas. The same 

 may be true of Stcrnopygus macrunts. 



It is seen above that the ancestors of one of the genera pecu- 

 liar to the Guayas, Pseudopxcilia, came from the north, those 

 of another, Paracctopsis, from the east. The other five do not 

 give very clear evidence in favor of the eastern or northern origin 

 of the Guayas fauna. 



Saccodon is related to Parodon found both in Colombia and 

 east of the Andes. Its ancestors may have come from either 

 place. 



Phenacobrycon is a derivative of Bryconamericus, an artificial 

 conglomeration of fishes, allied to Astyanax, abundant both east of 

 the Andes and in Colombia. 



The nearest relative of Pscudochalceus is Hollandichthys of 

 southeastern Brazil. Are they of independent origin from Astya- 

 nax? Does the territory between them contain related forms? 



Landonia is a minute derivative of Astyanax, a genus which 

 is found everywhere. I do not see that it gives any evidence on the 

 origin of the ancestors of the Guayas fishes. 



Rhoadsia was mentioned above. It belongs to a subfamily pecu- 

 liar to the Pacific slope of Ecuador and Colombia which also extends 

 to Costa Rica. The young show all the characters of the Cheiro- 



