FRILLS AND FUNDAMENTAL BARS AS PLUMAGE CHARACTERS. 



147 



appears as readily — expresses itself now in projecting feathers, now in feathers 

 lying more smoothly. 



Another similar hybrid shows similar conditions, except that the median crease 

 extends down the whole throat and breast (text-fig. 29, B, C), and more feathers 

 may sometimes be curled or tilted out of position. 



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Text-figdre 28. — Three stages of frill and feathering in a Juvenal African owl-pigeon (C2) hatched May 4, 1900. 



X 1. Wilson del., 1900. 



A. Age 17 days, shows the wide median tract, which was unfeathered at first and in width and appearance much 



like that seen in the common x orientalis hybrid of text-fig. 25. Pin-feathers are appearing, and a few are 

 turned mediad and a little upward; about 5 pins point upward. 



B. The same, May 30, 1900; age 26 days. The mid-tract still bare above; under base of beak this tract is 12.5 mm. 



wide; but the sides of this area are covered with pin-feathers. A few pins on each side are turned upward ; some 

 turn up and inward. In the very center of this mid-area may be seen two pins parallel, but turned in opposite. 

 Lower down the side-feathers meet in middle line; and just above place of meeting are about 9 feathers of the 

 mid-area turning in different directions. The upper side-feathers are pushed apart in the figure, to show the 

 area covered with pin-feathers. In situ, the feathers are 15 mm. apart near the middle height, i.e., midway 

 between the beak and the place where the feathers first meet in middle line. 



C. The same, June 9, 1900; age 30 days. The bare under-chill area of the 26-day stage is now covered, some feathers 



still showing there as pins. Lower on throat and upper breast the oppositely directed pins of the earlier stage 

 have expanded and (still in opposition) form a frill. 



In an adult Geopelia striata I have seen a full breast-crease showing something 

 of the same transient nature (text-fig. 26, fig. B). In a just-hatched G. humeralis 

 I found the down feathers of the throat curved upward — the contrary of the normal 

 slant of the later feathers of this region — and presenting a bristling appearance. 



The Breast- Crease and Frill in Common Pigeons. 



An adult male homer (B 1) shows a breast-crease and a small breast-frill. This 

 breast-frill is somewhat of a puzzle, as neither parent shows any trace of such a 

 thing. 8 It may be, however, that all pigeons are "liable" to this. It corresponds 



8 A young of this homer — the next bird to be described — has the breast-frill. — Ed. 



