230 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 150 



I have recorded the soft parts in the race asarae of Paraguay and 

 northern Argentina, as foUow^s (Wetmore, U. S. Nat. Mus. Bull. 133, 

 1926, p. 110) : Iris dark brown ; bill black, except for the base of the 

 mandible, and the space htlovf the nostril on the maxilla, vi^hich are 

 light gray ; cere and gape chamois ; tarsus and toes dull yellovi^ ; claws 

 black. The head and foot colors are definitely duller than in 

 Buteogallus anthracinus. 



Two subspecies, similar in size but differing in color pattern in the 

 tail, are found in Panama. 



Plumages of this species and those of Buteogallus anthracinus are 

 so similar, in both adult and immature, that close attention to detail 

 is required to separate them. This is true particularly in their 

 identification in life. With adult birds of the present species close at 

 hand, the white barring on the tibia may be visible, and in any stage 

 the longer legs may be noted, as well as the blacker bill, and more 

 slaty color of the side of the head. These colors, however, are less 

 strongly marked in immature individuals. 



The two black hawks under discussion differ in certain structural 

 details which have led to allocation of the larger one in a separate 

 genus, Hypomorphnus of Cabanis. Amadon (Auk, 1949, p. 54) 

 questioned the validity of this separation, and in a later paper 

 (Amadon and Eckelberry, 1955, p. 68) he gave some further discus- 

 sion in which he listed both species under the genus Buteogallus. 

 The structural differences between the two may be summarized as 

 follows : 



Greater Black Hawk: Tarsus longer, more than 110 mm.; 

 space between the broad, undivided plates at the front of the lower 

 end, and those on the base of the middle toe, longer, measuring 20 

 mm. or more; the intermediate scutes graduated progressively from 

 larger to those much smaller ; loral area, the anterior region of the 

 forehead adjacent to the cere, and the chin more heavily feathered ; 

 wing more rounded, the primaries less than 20 mm. longer than sec- 

 ondaries. 



Lesser Black Hawk : Tarsus shorter, less than 100 mm. ; space 

 between the broad, undivided plates at the front of the lower end 

 and those on the base of the middle toe shorter, measuring 12 mm. or 

 less; the intermediate scutes larger, with the transition from larger 

 to smaller abrupt, without gradual change in size ; loral area, anterior 

 region of the forehead, and chin scantily feathered; wing more 

 pointed; primaries from 40 to 70 mm. longer than the secondaries. 



Buteogallus aequmoctialis of eastern South America, type species 

 of the genus Buteogallus, agrees with the lesser black hawk in the 



