368 



PATAGONIAN EXPEDITIONS I ZOOLOGY. 



Range of the PcEciliidae. 

 To Illustrate the Origin of the South American Fresh-water Fish-fauna. 



them from the American to the African shore. Nevertheless, Fnndu- 

 his is found on both sides of the Atlantic, and there must have been an 

 intermigration much more recent than the youngest possible land con- 

 nection between Africa and South America, or else there has been a very- 

 long persistence of this genus. A land connection, while not absolutely 

 required for this family, would be very convenient. 



The Siluridcs are in part marine. All of the South American forms of 

 Sil/tridcs can be derived from the marine TacJiisurince and the same is 

 probably true of the African members of the family. Furthermore, the 

 catfishes are found in North America, Europe and Asia, and have been 

 recorded in North America also from the Tertiary. A land connection 

 between Africa and South America is, therefore, not absolutely required 

 to account for their presence in both continents, though, as in the case of 

 the PosciliidcB such a connection would be very convenient. 



The CichlidcB and CharacidcB are abundant in tropical America and in 

 Africa, a few species of CicJiUdcE being also found in India. There is no 

 known means by which these two forms could have crossed the existing 

 gap between Africa and South America. There has been no exchange 

 of species in recent times, for there is no species or genus common to the 



