Todd — Studies in the Tyrannidce. 23 



1135, 1136 (range; crit.). — Hellmayr, Abhand. K. Bayerischen Akad. 



Wiss., Math.-phys. KL, XXVI, 1912, 26, 90 (PeLxe-Boi and San Antonio 



do Prata, Brazil; range; crit.)- — von Ihering, Rev. Mus. Paulista, IX, 



1914, 440, 480, pi. 8, fig. 9, pi. 9, fig. 3 (nest and eggs). 

 Myiobius xanthopygus xanthopygus Ridgway, Bull. U. S. Nat. Mus., IV, 



1907, 487 (diag.; references). 

 Myiobius mastacalis Todd, Ann. Carnegie Mus., VIII, 1912, 208, in text 



(crit.). — Brabourne and Chubb, Birds S. Am., I, 1912, 296 (ref. orig. 



descr.; range). 



Description.— Male: above olive green, the pileum with a partially con- 

 cealed median vertical spot of lemon chrome; rump barium yellow; wings 

 dusky, externally more or less light brownish olive, the remiges edged with 

 buffy below; tail and upper tail-coverts plain dark brown or dusky; under 

 parts Martins yellow, the throat and sides of the head paler and duller, the 

 breast, sides, and crissum more or less shaded with old gold; "iris brown; 

 feet flesh gray; bill black above, pale below. " Female similar, but smaller, 

 and the vertical spot wanting or reduced to a trace. 



Measurements. —Male: wing, 64-71 (66.5); tail, 55-61 (58); bill, 10.5- 

 11.5 (11); tarsus, 15.5-17 (16.5). Female: wing, 55-62 (59); tail, 50-54 

 (52.5); wing, 10-11 (10.5) ; tarsus, 13.5-15 (15). 



Range. — Brazil, from the Amazon and Madeira Rivers south to Sao 

 Paulo and east to Bahia. 



Remarks. — This species was described by Maximilian, Prince of Wied, 

 just one hundred years ago, his types being stUl preserved in the American 

 Museum of Natural History. Four years later it was given another name 

 by Spix, but in the meantime Wied had concluded that his bird was identical 

 with the Muscicapa barbata of Gmelin, and in 1859, when Cabanis finally 

 became satisfied that the Brazilian bird was really distinct from that of 

 Cayenne, it was Spix's name and not Wied's that was adopted. Not 

 until 1906, indeed, when Mr. Hellmayr critically examined Spix's types, 

 pointing out the pertinence and priority of Wied's name, did -mastacalis 

 finally come into use. Numerous authors had in the meantime followed 

 Sclater's lead in denying recognition to the Brazilian form, and with the 

 nomenclature of the group in such a confused state it was little wonder that 

 without adequate material for comparison they could not agree. The 

 late Count von Berlepsch, however, expressed a decided opinion on this 

 point in 1888, which was fully indorsed by Mr. Hellmayr in 1912. We 

 can not follow this eminent authority, however, in considering M. 

 mastacalis only subspecifically separable from M. barbatus. While the 

 two forms are undoubtedly closely related, we have yet to see a specimen 

 that can not be unequivocally referred to one or the other. In mastacalis 

 the rump and under surface are obviously paler than in barbatus — barium 

 yellow or naphthalene yellow, instead of picric yellow or Martins yellow — 

 and the latter is shaded with old gold instead of citrine. There is a marked 

 variation, however, in the amount of this shading, some specimens lacking 

 it entirely (except on the tibiae and crissum), while in others it is conspicu- 

 ous. These differences appear to be correlated with a variation in the color 

 of the upper parts, the examples with the most buffy suffusion having the 



