x BIRDS OF LA PLATA 



belongs to the Patagonian Sub-region of the Neo- 

 tropical Region* 



The species known to me personally number 233, 

 but many more have been added since I left the 

 country* The exclusively Neotropical types in my 

 list include Tanagers, Trupials, Tyrant-birds, Plant- 

 cutters* Wood-hewers, Ant-birds, Gallito birds, Hum- 

 ming-birds, Screamers, Courlans, Jacanas, Seed- 

 snipe, Tinamus, and Rheas in all eighty-four 

 species* 



Thus in this district the exclusively South American 

 forms, or families, are in a minority ; but if we take 

 the whole of the Argentine country, these exclusive 

 forms and the widely-distributed forms are pretty 

 evenly balanced* Finally, if we take the entire 

 Neotropical Region we find the exclusively South 

 American forms in a majority* The Humming- 

 bird family alone numbers over four hundred 

 species, the Tanagers about the same number, 

 while two other Passerine families, Tyrants and 

 Woodhewers, count together five hundred at least* 



We have also to take into account that in the 

 families that are universal in their distribution there 

 are groups, genera and sub-families greatly modified 

 in form. Thus, in the Thrush family we have the 

 Mocking-birds, and as in the Thrush family so do 

 we find divergent types in Wrens, Finches, Cuckoos 

 and other families. 



To sum up* We have in the universally distri- 

 buted families, groups and genera, which exhibit the 

 peculiar impress of the region they inhabit (in this 



