350 Observations on the 



By the preceding generalities, it will be seen that almost all the 

 groups of predatory birds are common to the old world and to the 

 new. 



To recapitulate, we may state, that the only genera belonging ex- 

 clusively to America, are, among the vultures, the Sarcoramphi 

 and Cathartes, replacing in this quarter of the world the true vul- 

 tures, which are peculiar to our own hemisphere ; among the Falco- 

 nidae the small group of Caracaras, which have no analogues in the 

 old world, and which diifer from the vultures only in their forms, 

 for their manners really connect them with that genus. The harpy* 

 and the rostramet are likewise birds exclusively American, without 

 any analogues in Europe ; for none of our eagles are so strong as the 

 harpy, and none of our birds so sociable as the rostrames. 



Let us now consider the birds of prey with respect to their geo- 

 graphical distribution, or the number of species which the different 

 localities of South America present to our notice. 



We shall divide the whole extent of country to which our obser- 

 vations extend, into three zones ; and these three zones shall each 

 be considered in three points of view, namely, in regard to their la- 

 titude, their elevation above the level of the sea, and the nature of 

 the countries which compose them. 



Our Jirst zone extends from the 11° of latitude to the 28°, and 

 in elevation from to 5000 French feet above the level of the sea ; 

 our second, from 28° to 34 s of latitude, and from 5000 to 11,000 feet 

 in height ; our third, from 34° to 45° of latitude, and comprehends 

 every elevation above 11,000 feet. 



The Jirst zone of' latitude, (that which extends from the 11° to 

 the 28°) besides its immense plains and forests, naturally compre- 

 hends the most elevated tracks of the Andes ; it, therefore, possesses 

 the greatest number of species ; for, independently of such as are 

 peculiar to the warm and temperate zone, we there find the kinds 

 which inhabit a lower latitude, the proportional decrease of heat, as 

 we ascend the plateau of the Andes, soon rendering the temperature 

 of this latitude equal to that of the most southern. Thus when we 

 regard in the aggregate all the species comprised within these two 

 parallels, without taking into account the zones of elevation, we find 

 them amount to thirty-eight, while the total number of species ob- 

 served does not exceed forty-one. According to this calculation there 

 will only remain for the two other latitudinal zones, three species not 

 found in the first, and peculiar to the southern plains. This propor- 

 tion will at first appear enormous, but the explanations on which Ave 

 are about to enter will make it seem less extraordinary. 



If we consider, in reference to this first zone, the species confined 



* Harpyia. f Cymindis. 



