FAMILY FORMICARIIDAE 227 



cubated. The young when hatched "had dark flesh-colored skin 

 wholly devoid of down, and the interior of their mouths was yellow." 



GYMNOPITHYS BICOLOR BICOLOR (Lawrence) 



Pithys bicolor Lawrence, Ann. Lye. Nat. Hist. New York, vol. 8, 1863, p. 6. 

 (Atlantic slope near the Panama Railroad, Canal Zone, Panama.) 



Characters. — Forehead and side of head back of the eye dark 

 gray ; very faintly more reddish brown above. 



A male, taken at Juan Mina, Canal Zone, January 13, 1961, had 

 the iris dark brown ; mandibular rami and maxilla, except as noted, 

 dusky neutral gray, cutting edge of maxilla to tip, and rest of mandi- 

 ble neutral gray ; tarsus, toes, and claws neutral gray ; bare skin on 

 side of head light grayish blue. Two males from Armila, San Bias, 

 February 21 and 27. 1963, had the iris bright reddish brown; cutting 

 edge and tip of maxilla and distal half of mandible neutral gray; rest 

 of bill, including mandibular rami black ; tarsus, toes, and claws 

 neutral gray. 



Three females, collected in mist nets at Armila, February 27, 1963, 

 had the iris warm brown, but otherwise were like the males from 

 this locality. 



Measurements. — Males (10 from Canal Zone, Colon, and Province 

 of Panama), wing 73.3-76.4 (74.6). tail 43.3-47.5 (45.2), culmen 

 from base 19.8-21.2 (20.3), tarsus 27.0-28.5 (27.5) mm. 



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

 San Bias), wing 70.O-74.6 (73.0), tail 42.0-44.8 (43.7), culmen from 

 base 19.0-20.8 (19.8). tarsus 26.3-27.9 (26.9) mm. 



Weight, J' 33.1 grams (Gamboa. August 10, coll. R. S. Crossin). 



Resident. Locally common in Tropical Zone forests on the Pacific 

 slope from Santa Fe, Veraguas, east through Darien, to 575 meters 

 in the mountains ; on the Caribbean side from the Rio Calovevora, 

 northern Veraguas east through the Comarca de San Bias. 



The report by Salvin ( Proc. Zool. Soc. London, 1867, p. 145), 

 repeated by Salvin and Godman (Biol. Centr.-Amer., Aves vol. 2, 

 1892. p. 221 ) of a specimen (now in the British Museum in London), 

 collected by Arce from Santa Fe, Veraguas, is verified by a series in 

 the American Museum of Natural History taken by R. R. Benson in 

 1926. He secured others on the Caribbean slope on the Rio Calo- 

 vevora. 



These are birds of the undergrowth in forest, found occasionally 

 singly, more often in pairs or several in loose association, almost in- 

 variably over moving ant swarms. In this association they tend to 



