332 Remains of an extinct gigantic Bird. 



It is not easy to decide whether the species of Rhea to 

 which these bones belong was identical with the existing 

 R. americana. I have observed nothing in the few remains 

 at my disposal that would contradict that view; and I con- 

 sequently think that the ancient and the modern Rhea 

 are of one and the same species ; at the same time it must 

 be admitted that additional discoveries of the bones of the 

 ancient bird may possibly bring to light differences which 

 could not be inferred from the insufficient fragments of 

 bones now before us. 



But if the interpretation here offered of the bones which 

 have hitherto been looked upon as remains of an extinct 

 gigantic Alectorid be true, at any rate in the main — that is to 

 say, so far as the generic determination goes, — then it will 

 be readily perceived that it must to a very considerable 

 extent modify the opinion hitherto prevailing, that all the 

 laws which hold good for the relation between the existing 

 and the next preceding mammalian fauna of South America 

 are equally valid in respect of the class of birds. On the 

 contrary, there is an essential and fundamental difference. 

 There is no indication whatever of the class of birds having 

 possessed large extinct representatives, which could be said 

 to exhibit a somewhat similar relation to the birds now living 

 as that which the gigantic extinct Brazilian mammals present 

 as regards the existing fauna. 



I do not mean wholly to deny that the remains of birds 

 found in Brazilian caves may in some cases belong to really- 

 extinct species ; on the contrary, I consider this very pro- 

 bable. . But it is only through a renewed careful examination 

 of the bones that it can be ascertained how many really 

 extinct species have been discovered — or in other words, the 

 exact proportion between really extinct and still living species 

 in the cave-finds. Under all circumstances it may even now 

 be asserted, with all confidence, that the extinct bird-fauna of 

 which the remains are found in the caves of Brazil differs from 

 the existing fauna in a much less degree than the mammalian 

 fauna which is buried there. 



