348 ANNUAL REPORT SMITHSONIAN INSTIfTUTION, 1937 



8. SOUTH AMERICA (AND AFRICA) 



In South America we have a very different picture. ^^ The known 

 fossil record is so fragmentary as to be of no particular importance, 

 but the living fishes are exceedingly instructive. Of the living true 

 fresh-water fishes of South America, not a single species, genus, or 

 family is identical \vith truly North American groups. In fact the 

 South American fishes show greater dissimilarity to those of North 

 America than they do to those of any continent except Australia, 

 which has no fresh-water fishes at all of my primary division save 

 for one lungfish and one osteoglossid. 



Certain apparent similarities are at once disposed of. The primitive 

 bony fishes of the family Osteoglossidae, which appear to have become 

 extinct in North America in the Eocene, exist today in South America. 

 But they also exist in Africa, the Malay Archipelago, and Australia, 

 and, as I shall show a little later, I believe that their mere presence 

 loses any great significance in Tertiary zoogeography. Single species 

 of the South American characins and ciclilids have reached Texas, 

 but in each case the migrant is a generalized, aggressive fish, the 

 recent migration path of which is clearly evident. The cyprinodonts 

 fonn a different typo. The viviparous cyprinodonts of the family 

 Poeciliidae are common from Delaware, Illinois, and Arizona to 

 western Ecuador and northern Argentina. Unknown as fossils, 

 they may have developed in Central America, possibly from ancestors 

 similar to the goodeids, which are autochthonous in the Mexican 

 plateau. The oviparous cyprinodonts of the family Cyprinodontidae 

 likeNvise occur from central North America to Argentina, but it has 

 recently been shown (Myers, 1931) that the dominant South American 

 genera are closely related to African rather than to North American 

 forms." At auj^ rate, all the cyprinodonts except the North American 

 cave fishes belong to the secondary class of fresh-water fishes. 



South America is the richest of all the continents in fresh-water 

 fishes. The largest section of the fauna is formed by Ostariophj^si. 

 Five families of characins are found of which only one, the most 

 generalized, is shared with any other continent (Africa). There are 

 11 famiUes of catfishes, as well as the gymnotid eels, none of wliich 

 are found an3^where else save for a few aggressive migrants which 



» The peculiar, depauperate, Patagonian fauna is not here considered. Its only close relationship, as 

 shown by the lampreys, galaxiids, and aplochitonids, is with New Zealand and South Australia, and this 

 points to either an Antarctic connoction or sea migration, which I do not think impossible for any of the 

 three groups. 



» Except for the semimarine subfamily Cypriuodontinae of southern North America and the Caribbean, 

 of which Carrionellus is known from the Tertiary of Ecuador. The exact relationship of the autochthonous 

 Orestiatinae of Lake Titicaca is unknown. 





