FAMILY PIPRIDAE 337 



The question is one of definite interest that merits study. Merely 

 as discussion, it may be noted that in examination of several hundred 

 specimens of the three forms concerned throughout their range I 

 have seen no hybrids of any nature. To anyone familiar with the 

 geographic areas concerned, it is obvious that forest destruction, 

 through human activities, with resultant restriction in the original 

 habitat, has been extensive. Because of this, the two forms found 

 together by Dr. Willis, presumed formerly to have been separated, 

 now may be mingled, a circumstance possible but less probable under 

 the normal condition. Dr. Willis in personal discussion has informed 

 me that the woodlot where his observations were made was a forest 

 remnant, isolated in pasturelands. The result might be interpreted as 

 similar in a sense to the hybridization well known among ducks, as 

 between males of the mallard and females of a variety of species. 



Lowe (Ibis, 1942, pp. 50-83) in an account of the anatomy of the 

 Golden-collared Manakin (made from specimens of nominate vitel- 

 Unus, but applying to the species as a whole) noted the considerable 

 development of muscles in the breast, shoulder regions, and the upper 

 leg. This he attributed to the special display in jumping and flight 

 of males. He mentioned also the thickened secondaries, in which the 

 quills are not fastened firmly to the ulna as usual in birds, but are at- 

 tached loosely to a tendon with large muscle slips that allow unusual 

 mobility. They thus control the loud snapping and other mechanical 

 sounds made by the wings. The muscular development he described 

 is clearly evident during preparation of specimens. 



MANACUS VITELLINUS VITELLINUS (Gould) 



Pipra vitellina Gould, in Hinds, R. B. (editor), Zoology of the Voyage of 

 H. M. S. Sulphur, under the command of Sir Edward Belcher, R.N., 

 F. R. G. S., etc., during the years 1836-1842, vol. 1, pt. 3 (Birds, pt. 1), October 

 1843, p. 41, pi. 21. (Panama = Panama City, Panama.) 



Characters. — Male, foreneck, sides of head, and band across 

 hindneck more orange ; posterior under surface greenish ; rump and 

 upper tail coverts somewhat darker, duller, more grayish green. 



Female, above lighter, brighter olive-green ; lighter, more yellowish 

 on breast and abdomen ; tail and wings faintly duller. 



An adult male from Juan Mina, Canal Zone, January 12, 1961, 

 had the iris dark brown ; maxilla and tip of mandible black ; base of 

 mandible dusky neutral gray ; tarsus and toes dark orange ; claws 

 dusky neutral gray. In another, from Canita, Panama, February 6, 

 1962, the iris was dark wood brown ; base of mandible dark neutral 

 gray ; rest of bill black ; tarsus and toes dark orange ; claws black. One 



