FAMILY TYRANNIDAE 585 



a whole appears longer in body. The tarsus is about equal in length 

 in the two groups, but the toes in Ornithion are smaller. These 

 structural differences between the two do not appear to support the 

 suggested union. 



Differences in coloration between the two populations found in 

 Microtricciis are not great but in detail show no overlap. Those from 

 Mexico south through Nicaragua, continuing beyond on the Pacific 

 slope of Costa Rica, have the crown slate color and the white super- 

 ciliary longer. Those from the Caribbean slope of Costa Rica south 

 through Panama to Colombia and Venezuela have the crown rather 

 sooty brown and the superciliary less in length. The difference is 

 slight but appears specific as it is definite without evidence of any 

 intergradation. It is interesting to note a typical specimen of the 

 northern semiflavus from San Juan del Norte, on the Caribbean coast 

 of southeastern Nicaragua, especially since in Costa Rica immediately 

 to the south the nominate form of brunneicapillus is found. The 

 northern semiflavus in Costa Rica is confined to the Pacific drainage. 

 Dr. Paul Slud (Bull. Amer. Mus. Nat. Hist., vol. 128, 1964, pp. 272- 

 273) in his studies in Costa Rica noted slight differences in calls 

 between the two. His conclusion that the two merit treatment as 

 separate species on present information seems justified. 



Microtriccus b. brunneicapillus beyond Panama continues in north- 

 western Colombia, where it is recorded at present from central Choco 

 (Nuqui) on the Pacific Coast east to the middle Magdalena Valley. 

 To the eastward in the Santa Marta region and extending into western 

 Venezuela the bird becomes paler yellow on the under surface and 

 lighter green above, this marking the race dilutus described by Todd 

 (Proc. Biol. Soc. Washington, 1913, p. 171). 



LEPTOPOGON AMAUROCEPHALUS Tschudi: Sepia-capped 

 Flycatcher, Moscareta Cabeciparda 



Leptopogon amaurocephahis Tschudi, Cabanis Mss., Faun. Peruana, Aves, 

 1846, p. 162. (Sao Paulo, Brazil.) 



Medium size ; crown dull grayish brown ; back olive-green, with 

 light huffy brown bars on the wings ; side of head dull grayish brown. 



Description. — Length 120-130 mm. Adult (sexes alike), crown 

 sepia brown, paler on the hindneck ; back, scapulars, and rump olive- 

 green ; upper tail coverts russet-brown ; tail dull brown edged with 

 pale brown ; wings dusky ; lesser wing coverts olive ; middle and 

 greater coverts tipped with clay color to ochraceous-buff ; primaries 

 narrowly, and secondaries broadly, edged with pale yellowish olive; 



