I20 BIRDS OF THE REPUBLIC OF PANAMA PART 3 



ings, and subelliptical in form. As one end had been damaged, ac- 

 curate measurements could not be made. Schonwetter (Handb. Obi., 

 pt. 14, 1967, p. 32) gives the size in 12 eggs of this race as 24.0-26.0 X 

 17.8-19.3 mm. 



The systematic position of the genus Lochmias has not been certain. 

 Peters followed Hellmayr (Cat. Birds Amer., part 4, 1925, p. 236), 

 who placed it at the end of the family, following Sclerurus (but 

 without statement as to close affinity). 



Vaurie (Classification of Ovenbirds, 1971, pp. 13, 30-34) allies 

 Lochmias to Margarornis squamiger, sl species of South America, as 

 the two have a "remarkable and conspicuous color pattern" where 

 in both the undersurface has "large white or whitish spots on the 

 under parts which are narrowly edged with black and are tear-like." 

 The similarity in color pattern is the only resemblance, however, as 

 the two groups differ distinctly in body form and in manner of life. 

 The Margarornis group are arboreal forest birds, active in trees, and 

 with a slighter, less powerful body form that includes weaker skeletal 

 development. Lochmias may be found low down in shrubbery but is 

 more terrestrial, with strong legs and heavier wing elements. The 

 Two appear to differ too definitely to warrant the suggested association. 

 It is preferable to continue listing it at the close of the generic sequence 

 for the family until there may be definite reason for its shift elsewhere. 



Family FORMICARIIDAE : Ant-thrushes, Ant-shrikes; 

 Hormigueros 



The assemblage of species in this family, found only in the New 

 World, is one typically South American, with extension north through 

 Panama in diminishing number. Peters (Check-list Birds of the 

 World, vol. 7, 1951, pp. 153-273) listed 223 species. While of these 

 only 38 are recorded in Panama, where, widely distributed in the 

 Tropical and Subtropical zones, they form a varied and highly inter- 

 esting assemblage of birds. They diminish steadily in number north- 

 ward until only 10 reach Mexico, with the Barred Ant-shrike alone 

 recorded north as far as southern Tamaulipas. 



In Panama these birds are found throughout the mainland, but 

 only two species appear to have ventured to off-lying islands. 

 Thamnophiliis doliatus is resident on Isia Coiba, off western Veraguas, 

 and on Isla Pedro Gonzalez in the Archipielago de las Perlas. Both 

 populations are darker than the mainland race Thamnophilus d. 



