5o8 BIRDS OF THE REPUBLIC OF PANAMA PART 3 



March 28, 1935, I found one building a nest in moderately heavy forest near a 

 small stream. It was about 2 meters from the ground, attached to a long, slender 

 aerial root, hanging down from high in the treetop. Newly begun, it was an 

 accumulation of dried inflorescences of Myriocarpa ysabalensis, a species of 

 Urticaceae. The nest grew slowly, as it was April 4 before the bird began to 

 separate the dangling fibers to form a nesting chamber. And on April 17 the 

 builder was still lining this chamber. When nearly finished the nest slipped 

 from the end of the slender supporting root and fell. Although I fastened it in 

 its original position, it was abandoned. 



The structure had grown to a length of nearly a meter, with a diameter of 

 175 mm. Midway the material had been spread apart to form the nesting 

 chamber. In the small proportion of total bulk actually occupied by the nesting 

 chamber this nest may be compared to that of the Royal Flycatcher. It differed 

 chiefly in its more homogeneous material, more regular form, and greater 

 diameter. 



Only one bird, assumed to be a female, worked on it. 



Zimmer (Amer. Mus. Nov., no. 1043, 1939, pp. 10-12, fig. 1) has 

 described the curious curved form of the wing. In this the four outer 

 primaries of the adult male "have the basal part of the shafts arcuate, 

 very strongly on the tenth. In addition, the terminal part of these 

 feathers is twisted upward and outward. All of the primaries are 

 more or less twisted in shape and position, so that in the closed wing 

 their outer margins are lifted away from each other, and come into 

 close contact only basally and near their tips. The 7th and 8th 

 primaries are further modified in another way. About two-thirds of 

 the distance toward the tip of the feather the outer web is abruptly 

 narrowed and the inner web equally abruptly widened, with a spot 

 of brighter color and a slight disintegration of the web on the outer 

 web at the point of change. On the inner web . . . there is a dark 

 submarginal line. . . . Along this line, the vane of the feather bends 

 readily, but between it and the shaft it is unusually stiff." 



Although I have had these birds frequently under observation, I 

 have noted no apparent use of this unusual structure. 



TOLMOMYIAS SULPHURESCENS FLAVO-OLIVACEUS 

 (Lawrence) : Yellow-olive Flycatcher, Moscareta Azufrada 



Rhynchocyclus flavo-olivaceus Lawrence, Ann. Lye. Nat. Hist. New York, vol. 8, 

 May 1863, p. 8. (Lion Hill Station, Panama Railroad, Canal Zone, Panama.) 



Rather small ; bill broad ; back olive-green ; abdomen yellow ; tail 

 slightly longer. 



Description. — Length 120-129 mm. Adult (sexes alike), crown 

 and hindneck somewhat grayish olive-green ; back, scapulars, lesser 

 wing coverts, rump and upper tail coverts bright olive-green; wings 



