FAMILY TYRANNIDAE 513 



February 8, 1962, the iris was mouse brown ; bare lower eyelid yellow- 

 ish green ; maxilla black, except at gape, which, like the mandible, is 

 dull buffy white ; tarsus and toes dull neutral gray ; claws black ; under 

 side of toe pads pale yellowish. Another male, from Armila, San 

 Bias, February 28, 1963, differed in having the iris warm brown ; gape 

 honey yellow ; tarsus and toes bluish neutral gray ; claws fuscous- 

 black. In other details, in the inside of the mouth, the inner face of 

 the mandible and the tongue were yellowish orange ; inner surface of 

 maxilla dusky at margin, shading to dull honey yellow in center. In a 

 female, from El Real, Darien, January 27, 1964, the iris was dark 

 brown ; maxilla black, mandible dull ivory-white ; tarsus and toes 

 bluish neutral gray ; claws fuscous-brown. 



Measurements. — Males (10 from Colon, Province of Panama, 

 Canal Zone, Darien, and San Bias), wing 70.8-74.7 (73.4), tail 

 56.5-64.6 (60.4), culmen from base 15.8-17.0 (16.2), tarsus 17.1- 

 18.6 (17.9) mm. 



Females (10 from Canal Zone, Province of Panama, Darien, and 

 San Bias), wing 67.2-72.6 (70.2), tail 53.5-58.1 (55.4), culmen 

 from base 15.6-17.1 (16.6), tarsus 17.5-18.2 (17.9) mm. 



Resident. Fairly common in forested areas ; on the Pacific slope 

 from the Canal Zone to eastern Darien (Jaque) ; on the Caribbean 

 side, from the Rio Indio (Chilar), western Colon, east to eastern San 

 Bias (Puerto Obaldia). 



In their forest haunt they range from the undergrowth up to the 

 lower tree crown, occasionally coming out into partly cleared areas. 

 They are found singly or in pairs, occasionally with several loosely 

 associated. Single birds may join traveling flocks of the smaller forest 

 birds. Alone, they may move rather rapidly among the branches, or 

 may rest quietly, merely turning the head about. 



Stomachs that I examined held insect remains. Goldman recorded 

 one seizing small flying insects in the air. The call is a low whis or 

 whees, with little carrying power. Eisenmann recorded the song as a 

 "very thin, but musically sweet, though monotonous, tee-tee-tee-tee." 

 Skutch (Anim. Kingd., vol. 59, 1956, p. 52) wrote that flycatchers of 

 the genus Rhynchocyclus "build retort-shaped nests" that differ from 

 those of the Yellow-margined Flycatcher (Tolmomyias assimilis) in 

 having large dead leaves in walls. He reports that they sleep in these 

 nests and suggests that some of these structures may be constructed 

 especially for this purpose. On Barro Colorado Island, Gilliard found 

 a nest April 13, 1937, with young about four days old. 



While the nest is known, no description of the eggs of this northern 

 race of the species has been found. 



