BIRDS OF NORTH AND MIDDLE AMERICA. 513 



cc. Under parts not slate-grayish. 

 d. Beneath light grayish olive or olive-gray, paler on throat, the abdomen whit- 

 ish or pale dull yellowish; above deeper grayish olive or olive-grayish. 

 (Myiochancs pertinax.) 

 e. Coloration deeper and more olivaceous, the abdomen more yellowish. 

 (Central and southern Mexico to Guatemala and British Honduras.) 



Myiochanes pertinax pertinax (p. 513) 

 ee. Coloration paler and grayer, the abdomen more wliitisli. (Northern Mexi- 

 co and Arizona; accidental in Colorado.) 



Myiochanes pertinax pallidiventris (p. 515) 

 dd. Beneath ochraceous-olive, passing into yellow posteriorly; above deeper 

 ochraceous-olive, more dusky on pileum. (Costa Rica.) 



Myiochanes ochraceus (p. 517) 



MYIOCHANES PERTINAX PERTINAX (Cabanis and Heine). 

 SWAINSON'S FLYCATCHER. 



Adults (sexes alike) in spr^ing.'^ — Above plain grayish olive, the 

 pileum slightly darker, with feathers more or less distinctly darker 

 medially ; wings and tail dusky grayish brown, the outer webs of rec- 

 trices passing into light grayish olive or olive-grayish on edges, the 

 primaries very narrowly and indistinctly edged with the same; second- 

 aries edged (except basally) with pale grayish, sometimes approaching 

 dull grayish white; mifldle wing-coverts margined terminally or tipped 

 with grayish olive or buffy grayish (more or less deep), the greater 

 coverts edged and tipped, or terminally margined, with same; sides of 

 head and neck similar in color to back, etc., but slightly paler, the 

 loral region somewhat intermixed with whitish ; chest and sides similar 

 in color to sides of head and neck, but usiuilly somewhat tinged with 

 buffy yellowish, the throat similar but paler, fading into dull whitish 

 on cliin; median portion of breast, abdomen, and under tail-coverts 

 pale yellowish buff}", the latter usually with more or less distinct gray- 

 ish V-shaped basal or central markings; axillars and under wing-cov- 

 erts buffy, the feathers with more or less of concealed portion pale 

 grayish; maxilla dusky brown to nearh^ black, mandible yellowish; 

 iris brown; legs and feet dusky brown or blackish. 



Adults in summer. — General color more grayish than in spring, the 

 abdomen, etc., usuall}^ more whitish. 



Adults in autumn^ — Similar to the spring plumage, but colors 

 deeper, the upper parts more decidedly olive, the lower parts more 

 strongly suffused with yellowish buff. 



Adult male. —Length (skins), 169-196 (1S9); wing, 102-114 (107.4); 



o Specimens taken from January to May, inclusive. 



6 September (or after summer molt) to .January, inclusive. (Some January birds are 

 indistinguishable from autumnal birds, while others are precisely like those taken in 

 April.) 



11422— VOL 4—07 ^33 



