74 ANNALS NEW YORK ACADEMY OF SCIENCES 



species of fishes as Arapaima, Osteoglossum and Electrophorus are not 

 found in Patagonia, because they are also not found in La Plata; but it 

 is strange that the Pygidse are found in Patagonia and Hoplias mala- 

 bricus (of the Characinidse) is not/because I found Hoplias to be one of 

 the best overland travelers of all the South American fishes. The absence 

 of Hoplias in Patagonia may be due to its being a tropical genus. 



The fact that Oeotria and the Oalaxidce are found in the Australian 

 realm is no evidence that Patagonia was connected with the same, be- 

 cause at least one of these forms is known to enter the sea. 35 The 

 absence of Diplomysle and Pygidse from the Antarctic and the Aus- 

 tralian realms seems to me to be far more conclusive static evidence that 

 these regions were not continuous than do the presence of Geotria and 

 Galaxidse in these two regions indicate that they were continuous. The 

 latter two genera could have extended their limits of distribution by way 

 of the sea. If a connection existed, Pygidae, being good overland trav- 

 elers, would have had a chance to enter the Australian realm. If Diplo- 

 myste is the most primitive living catfish, it, too, would have had a 

 chance to extend its limits of distribution. Hence, only marine fresh 

 water and no strictly fresh-water species or genera are common to these 

 regions, and I take this as strong evidence against a former connection 

 between Patagonia and the Australian realm. In fact, Patagonia has no 

 Osteoglossidae, no Dipnoi and other forms found in Australia. 



Origin of the South American Fishes 



In the Princeton Patagonian report on the fishes, Professor Eigen- 

 mann states that fishes probably interchanged before the beginning of 

 the Tertiary epoch between Africa and South America by way of a land- 

 bridge between Guiana and Africa. The following objections can be 

 raised against this hypothetical view : 



1. There is no positive evidence that either the Characinidae or the 

 Cichlidae as such existed previous to the Tertiary, but I grant the possi- 

 bility of their existence in late Cretaceous times. 



2. All of the known fossil fishes indicate a northern origin of the living 

 tropical fishes. 



3. There is no good geological evidence in favor of the connection. 

 The evidence is all biological and paleontological and questionable in 

 kind. 



35 It is also probable that formerly both of these genera were able to enter the sea. 

 This is all the more true in view of the fact that much of Patagonia was covered by 

 Tertiary sea. 



