12 UNIVERSITY OF WISCONSIN STUDIES 



is also found in Southern Brazil; Creagrutus beni ranges along 

 the base of the Cordilleras from Bolivia to Caracas. 



Plecostomus plecostomus Linnaeus panaque. 



Hoplias malabaricus (Bloch) guabina. 



Hemigrammus marginatus Ellis sardina. 



Astyanax bimaculatus (Linnaeus) sardina. 



Gephyrocharax valenciae Eigenmann sardina. 



Creagrutus beni Eigenmann sardina. 



Lebistes reticulatus (Peters) sardina (top minnow). 



Symbranchus marmoratus Bloch anguila. 



Crenicichla geayi Pellegrin mataguaro. 



Aquidens pulcher (Gill) chusco. 



Of the twenty-three species listed, seventeen are widely 

 distributed or indigenous. Five other species are also found 

 in Trinidad. The geographical relationship of the fish fauna 

 of Lake Valencia and its tributaries is largely with the territory 

 toward the east. 



Fifteen of the species were collected in rivers, and five of 

 these were found in no other habitat. Thirteen species were 

 taken at the mouths of rivers and two of these were not found 

 elsewhere except in rivers. Ten species were found along the 

 shores of the islands in Lake Valencia; seven in and near the 

 rushes about the margin of the lake; four species in the deeper 

 parts of the lake. Three species found in rivers were found 

 nowhere else except on the shores of the islands. Four of the 

 species present in the lake were not collected in rivers; eleven 

 of those from rivers were not found in lakes. The three species 

 found in all habitats (Hoplias malabaricus, Astyanax bimacu- 

 latus, Symbranchus marmoratus) are widely distributed geo- 

 graphically. Aquidens pulcher, another widely distributed 

 species, was found in all habitats except rivers. 



The facts described in the last paragraph may be taken to 

 mean that the river is the oldest habitat and the lake the 

 newest for the fishes in this region, because the former contains 

 the larger number of species. This view is supported by the 

 fact that toward the east, where the geographical affinities of 

 these fishes lie, there are practically no lake habitats and many 

 rivers. 



The same facts may be interpreted as indicating that, 

 because a river contains a greater variety of conditions (habitats), 



