552 BIRDS OF THE REPUBLIC OF PANAMA — PART 3 



shape the eggs may be short ovate and blunt or more elongate and 

 pointed. The measurements of seven eggs average 20.3x15.7 mm, 

 . . . extremes measured 22.0 X 15.0, 19.9 X 16.1, and 19.1 X 15.6 mm." 

 In the Cordillera Central of Costa Rica eggs were found between 

 April 9 and June 2. 



He describes the nestling at hatching as with a yellow to pinkish 

 skin that "bears sparse, dark gray down. . . . The nestling's bill, 

 tarsi and toes are bright yellow." 



Earlier writings have included frantsii as a subspecies of Elaenia 

 obscura. Zimmer (Amer. Mus. Nov. no. 1108, 1941, pp. 15-16) 

 doubts this relationship, pointing out the considerable gap in the 

 range of frantsii as well as its differences in coloration. The extensive 

 series that I have examined confirm his findings. Nominate frantsii 

 ranges north through Costa Rica to Nicaragua. In Honduras it is 

 replaced by Elaenia frantsii ultima Griscom (described in Ibis, 1935, 

 p. 550) of Honduras, El Salvador, and Guatemala, which is some- 

 what darker, less greenish olive above, and darker, more olivaceous 

 on the breast and sides. 



Lawrence named the species for Dr. A. von Frantzius, a German 

 naturalist, in recognition of his studies of the birds of Costa Rica. 



ELAENIA CHIRIQUENSIS CHIRIQUENSIS Lawrence: 

 Lesser Elaenia, Mononcita 



Blainea Chiriquensis Lawrence, Ann. Lye. Nat. Hist. New York, vol. 8, No- 

 vember 1865, p. 176. (David, Chiriqui, Panama.) 



Elaenia sordidata Bangs, Auk, vol. 18, no. 1, January 1901, p. 28. (San Miguel 

 Island =: Isla del Rey, Archipielago de las Perlas, Panama.) 



Medium size, somewhat smaller and more slender than the Moun- 

 tain Elaenia, with light area on tertials less prominent. 



Description. — Length 125-145 mm. Adult (sexes alike) above 

 grayish olive to olivaceous hair brown, with crown feathers somewhat 

 darker centrally, these markings forming faintly outlined streaks; 

 center of crown with concealed white bases, in some these reduced or, 

 rarely, absent ; wings dusky ; middle and greater coverts broadly 

 tipped with brownish gray to white ; inner secondaries narrowly 

 edged with white ; primaries edged distally with brownish gray to 

 somewhat greenish white ; tail dark grayish brown, edged with pale 

 grayish brown, and tipped lightly with white; sides of head some- 

 what paler than crown ; supraloral region and eye-ring paler, the 

 latter varying to white ; chin and throat dull grayish white ; f oreneck, 

 upper breast, and sides, somewhat yellowish gray ; lower breast, 



