336 PATAGONIAN EXPEDITIONS : ZOOLOGY. 



List of Species WitJi Tlieir Known Disfribntion. 



In the following list : 



A indicates that the species has been recorded from the Amazon. 



L indicates that the species has been recorded from the La Plata, in- 

 cluding Rio Grande do Sul. 



* that the species is peculiar to this province. 



•-!:* j-j-^^t tiie genus is peculiar to this province. 



All the observations on the San Francisco basin as a possible center 

 of distribution apply with equal force on the coastal province. 



There are two facts that deserve emphasis: First at Taubate, in the State 

 of Sao Paulo on the Rio Parahyba, fossil fishes have been found in bitu- 

 minous shales. The definite geological horizon of these rocks has not 

 been determined and they contain no other fossils. These fossils belong, 

 according to Smith Woodward, to the genera Ariiis, a genus ijow very 

 abundant along the coasts of tropical America and entering fresh 

 water ; Tetragonoptenis, or its ally Astyanax, still abundant in the 

 Parahyba ; Percichtliys, now confined to the Patagonian region, and Acara, 

 a Cichlid. Von Ihering contends that the PercicJithys is not a member 

 of the Serranidcc to which PercicJitJiys belongs, but is a Ciciilid, and 

 Jordan makes a new genus Eobrycon of the fossil Tetragonoptents. 



Von Ihering is inclined to the opinion that the shales were .deposited 

 during the Tertiary in a lake more than 120 km. long, occupying the 

 valley of the Parahyba from the Serra de Mantaqueira to that of Bocaina. 



Second, while there are many genera in the Amazon and the La Plata 

 not found in eastern Brazil, there are also a number of species in the La 

 Plata basin and eastern Brazil that have not been found in the Amazon. 

 These are enumerated in the list of species of the coastwise streams and 

 indicate that there has been a certain amount of migration between the 

 La Plata and this region. The possible means of communication is indi- 

 cated in the description of the Parahyba. 



