202 Proceedings of the Biological Society of Washington. 



Bol. Acad. Nac. Cien. Cordoba, X, 1890, 402 (Cordoba, Argentina).— 



KoeNiGswALD, Journ. f. Orn., XLIV, 1896, 360 (Estado de Sao Paulo, 



Brazil; references). 

 Pyrocephalus swainsoni Gray, Hand-List Birds, I, 1869, 363 (in list of 



species). 

 Pyrocephalus cantans Gray, Hand-List Birds, 1, 1869, 363 (in list of species). 

 Myiarchus tyrannulv^ (not Mtiscicapa tyrannulus Miiller) Coues, Proc. 



Acad. Nat. Sci. Philadelphia, 1872, 71, part (Brazil; crit.). — Durnford, 



Ibis, 1878, 61 (Punta Lara, Argentina). — Sclater and Salvin, Proc. 



Zool. Soc. London, 1879, 616 (Typuani and Tilotilo, Yungas, Bolivia; 



D'Orbigny's records). — Durnford, Ibis, 1880, 418, in text (near Tucu- 



mdn, Argentina). — White, Proc. Zool. Soc. London, 1882, 608 (Oran, 



Salta, Argentina). 

 Myiarchus tyranninus (lapsus) Allen, Bull. Am. Mus. Nat. Hist., II, 



1889, 87 (Mapiri, Bolivia). 

 Myarchiis (lapsus) ferox Boucard and von Berlepsch, Humming Bird, 



II, 1892, 45 (Porto Real, Brazil) .—Hagmann, Bol. Mus. Gceldi, IV, 



1904, 220 (Wied's reference). 

 Myiarchus ferox ferocior (not Myiarchus ferocior Cabanis) Oberholser, 



Proc. Indiana Acad. Sci., 1918, 307 (diag.; range; crit.). 

 Myiarchus ferox swainsoni von Berlepsch, Ornis, XIV, 1907, 477 (in list 



of species). — Oberholser, Proc. Indiana Acad. Sci., 1918, 307 (diag.; 



range; crit.). 

 Myiarchus ferox cantans Hellmayr, Nov. Zool., XVII, 1910, 302, in text 



(southern Brazil; crit.). 



Subspecific characters. — Similar to Myiarchus ferox ferox, but upper parts 

 lighter, more brownish, and throat and breast slightly paler gray. 



Measurements. — Male: wing, 87-93 (average, 90.5); tail, 82-91 (86.5); 

 bill, 18-19.5 (18.7); tarsus, 19-22 (21). Female: wing, 83-89 (85); taU, 

 74-89 (81); bill, 16.5-18 (17.3); tarsus, 18-21 (20). 



Range. — From central Bolivia and Goyaz, Brazil, southward to the lati- 

 tude of Buenos Aires, Argentina. 



Remarks. — The characters distinguishing this southern race from the 

 typical form are precisely those separating venezuelensis from the latter. 

 Upon comparison the difference between swainsoni and venezuelensis proves 

 to be practically nil; they are so close that no one would think of formally 

 separating them if their ranges were continuous each with the other, but 

 they are in fact divided by the interposition of the dark form ferox, which 

 stretches from Guiana and the lower Amazon to the eastern base of the 

 Andes in Colombia. The only character we can find to separate swain- 

 soni from venezuelensis is in the color of the pileum, which is sUghtly more 

 brownish in the former, and more dusky in the latter, but the difference is 

 trifling and not constant — scarcely or not obvious, indeed, except in abso- 

 lutely fresh plumage. The yellow of the under parts varies considerably 

 in tone; it is much paler and duller in worn specimens. 



The early records of this form are involved in much confusion. Certain 

 of Azara's names have been quoted as belonging here, but we think without 

 justification. Burmeister's account is open to question, since he considered 



