298 



BIRDS OF THE REPUBLIC OF PANAMA PART 4 



sured 20.0 by 13.9 and 19.6 by 14.1 mm. The shells had little gloss." 

 The eggs hatched after 15 days of incubation, and the nestlings were 

 flesh colored, with a tinge of orange. Their natal down was a pale gray 

 and by their third day the young had sprouted pinfeathers, but on that 

 afternoon there was a heavy rainstorm that evidently killed the nest- 

 lings. Skutch never found another nest. 



G. a. chiriquensis differs from other forms of G. aequinoctialis in its 

 somewhat larger bill, duller dorsal coloration, and the greater extent of 

 black on the forecrown. Despite the wide separation in range, the Chi- 

 riqui bird is clearly a representative of aequinoctialis and Hellmayr's 

 (Field Mus. Nat. Hist., publ. 347, vol. 13, part 8, 1935, p. 440) listing 

 of chiriquensis as a subspecies of aequinoctialis is probably justified, 

 although most authors have kept them as separate species. It may also 

 be noted that there is a similar, though less extreme, gap in the distri- 

 bution of the races of Geothlypis semiflava, and geographical isolation 

 is, therefore, not necessarily a compelling argument for specific dis- 

 tinctness. 



GEOTHLYPIS SEMIFLAVA BAIRDI Ridgway: Olive-crowned 

 Yellowthroat, Reinita Gargantiamarilla Coronioliva 



Geothlypis bairdi Ridgway (ex Nutting MS), 1884, in Nutting, Proc. U.S. Nat. 

 Mus., 6 (1883), p. 398. (Los Sabalos, Nicaragua.) 



Small; upper surface yellowish olive-green; undersurface yellow; 

 male has forecrown and facial area black. 



Description. — Length 111-125 mm. Adult male, forecrown, lores, 

 and side of face to lower edge of throat black; rest of upper surface, 

 including tail and all of wings except primaries, yellowish olive-green; 

 primaries dusky with outer web edged olive-green; sides and flanks 

 olive-green; rest of undersurface, bend of wing, and underwing co- 

 verts bright lemon yellow. 



Adult female, like male, but black replaced by olive- green, more yel- 

 lowish on forehead and superciliary; olive wash on undersurface more 

 extensive. 



Immature, like female, but buffier below. 



Measurements. — Males (10 from Bocas del Toro and Costa Rica), 

 wing 57.2-62.0 (59.2), tail 42.7-52.4 (47.6), culmen from base 13.8- 

 16.1 (14.9), tarsus 20.1-22.9 (21.7) mm. 



Females (7 from Bocas del Toro, Costa Rica, and Nicaragua), wing 

 54.2-57.0 (55.7), tail 42.6-47.3 (45.1), culmen from base 13.9-15.2 

 (14.7), tarsus 20.1-21.8 (21.2) mm. 



