FAMILY JACANIDAE 375 



be hybrids. Two have maroon backs with trifid frontal lappets, and 

 also a small rictal lappet. Two others with only a tinge of maroon on 

 the back have a small median frontal wattle between the two large 

 ones, and also a rictal wattle. One other, fully adult is completely 

 black on the back, with a small middle frontal wattle, and large ones 

 in the rictal area. All others seen have shown the normal differences 

 described. 



Part of the confusion in understanding of the differences that sep- 

 arate the two has been due to individual variability in Jacana jacana 

 hypomelaena, the race of the southern species involved. This name 

 is applied to the population found through most of Panama and 

 northern Colombia, in which the head and body are deep black. It 

 appears that this is a condition of melanism in which the dark pig- 

 ment conceals the chestnut brown pattern of the back and breast nor- 

 mal in other populations to the south. It is fairly common to find 

 specimens of hypomelaena in which a definite wash of brown is evi- 

 dent on the back and wings, often hidden by black tips of the feathers, 

 and an occasional individual in which there are definite chestnut 

 markings on back and breast. As the chestnut pattern is found also 

 in the northern Jacana spinosa, these aberrant individuals have been 

 attributed mistakenly to intergradation between the two groups, a 

 supposition supported by specimens of /. /. hypomelaena in which 

 the free margin of the frontal plate, through slight distortion in dry- 

 ing, appears to simulate the true central lobe of /, spinosa. The clear- 

 cut and striking differences in color of the frontal plate may be the 

 effective factor that separates the two groups during pair formation, 

 and thus maintains the two distinct. I have not seen a supposed in- 

 termediate adult specimen that could not be allocated specifically on 

 the characters that I have outlined. 



Current acceptance of Todd's designation of "Panama" as type 

 locality for this species (Ann. Carnegie Mus., vol. 10, 1916, p. 219) 

 requires amendment to western Panama in view of the limited range of 

 this bird in the Republic. The specific name spinosa of Linnaeus is 

 based solely on Edwards, Nat. Hist. Birds, 1743, p. 48, pi. 48. Edwards 

 was told that his specimen, "preserv'd a good while in spirits," lent 

 to him by Sir Hans Sloane, "was brought from Carthagena, South 

 America." It seems probable that it came from farther north in 

 Central America rather than from the limited area where this species 

 is found in western Panama. 



