Abstract
The classic ornithological work by Félix de Azara “Apuntamientos para la historia natural de los páxaros del Paraguay y Rio de la Plata” was one of the first descriptive texts dealing with the avifauna of the Southern Cone of South America. Azarays No. 18 vGavilán mixto pintadow has long been misidentified as a juvenile great black hawk (Buteogallus urubitinga ((Gmelin, 1788)). However, there are clear inconsistencies in the description of the plumage coloration, shape and measurements which make that identification erroneous, and Azarays No. 18 can in fact be convincingly identified as the juvenile plumage of the Harrisys hawk (Parabuteo unicinctus (Temminck, 1824)). The description by Azara contains numerous diagnostic characteristics for that species, and the measurements provided by him are inconsistent with those of the great black hawk, yet remarkably similar to those provided by the same author for the description of the adult No. 19 vGavilán mixto obscuro y canelaw. No scientific names have apparently ever been based on Azara No. 18.