FAMILY TYRANNIDAE 429 



the central axis, varying from thin lines to broader, heavier form, and 

 irregular blotches, coalescing to almost completely cover the smaller 

 end. The three measure 25.2 X 17.3, 26.0 X 18.1, and 26.1 X 18.0 mm. 

 To the west on the Pacific side of central Costa Rica in the low- 

 lands there is a grayer population, Myiarchus ferox actiostis, de- 

 scribed by Ridgway. And along the Pacific slope of western Colombia 

 one that also is grayer than the population of mainland Panama, but 

 differs from actiosus in being darker, slightly more olive-gray, with 

 the crown somewhat lighter than the rest of the dorsal surface. This 

 is the race audens Wetmore, described in 1953 from specimens col- 

 lected by M. A. Carriker, Jr., at Nuqui on the coast of central Choco. 



MYIARCHUS TUBERCULIFER (Lafresnaye and d'Orbigny) : 

 Dusky-capped Flycatcher, Cabezota Gorranegra 



Tyrannus tiiberculifer Lafresnaye and d'Orbigny, Syn. Av., Mag. Zool., vol. 7, 

 cl. 2, 1837, p. 43. (Guarayos, Bolivia.) 



Smaller than other species of the Crested Flycatchers {Myiarchus) 

 found in Panama ; crown dull black ; back greenish olive ; anterior 

 under surface light gray ; lower breast and abdomen yellow. 



Description. — Length 150-165 mm. Crown sooty brown to black; 

 rest of upper surface olive to greenish olive, with upper tail coverts 

 browner ; tail dark grayish brown, with outer webs edged with rufous 

 (in subspecies hang si) or only slightly paler than central area (in 

 subspecies brunneiceps) ; wings dusky ; greater to lesser wing coverts 

 edged with dull buffy brown ; secondaries edged narrowly with dull 

 white ; inner primaries bordered narrowly with cinnamon-rufous to 

 buff ; foreneck and breast light gray ; rest of under surface light 

 yellow ; axillars and under wing coverts pale yellow ; inner webs of 

 wing feathers edged with buff. 



James Bond (Twelfth Suppl. Check-1. Birds West Indies, July 12, 

 1967, p. 4) holds that Myiarchus barbirostris (Swainson) of Ja- 

 maica, described in 1827, is conspecific with Myiarchus tuherculifer 

 of 1837, so that the older barbirostris should be used as the species 

 name for this group of subspecies. Lanyon (Bull. Amer. Mus. Nat. 

 Hist., vol. 136, art. 6, 1967, pp. 342-346) from his studies of voice 

 in these birds considers this not proven. He suggests instead that 

 barbirostris should be treated as a separate monotypic entity. The 

 question is one that requires further study for firm decision. 



The species here accepted as tuherculifer is widely distributed 

 from southern Arizona and New Mexico through Mexico, Central 

 America and South America to Paraguay, Brazil, and Argentina. 



