144 



ORTHOGENETIC EVOLUTION IN PIGEONS. 



have appeared (few in number over the whole surface), but less advanced in the 

 middle than at the sides. At this age two has a smooth breast and a short crease 

 above of about 1 inch in length, and shallow as compared with one. Two is larger 



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TEXT-FIGURE 25. The breast-frill in juvenile hybrids, hatched February 16, 1900. 18 days old. Same size. Wilson 

 del., March 6, 1900. Sire, a hybrid from common pigeon X Twrlwr orientalis. Dam, a common pigeon. 



A. Hybrid (No. 1 1) is black in color. A remarkably wide median tract, without any feathers or pin-feathers in sight, 



within area marked by dotted lines. The feathers of the breast were well unfolded and covered over much of 

 the unfeathered tract, closing up for about an inch of the middle breast, but leaving a naked area above and 

 another below. The line of junction of feathers formed a deep crease or groove. Very scanty down at time of 

 hatching. 



B. Hybrid (No. 1 2) was less black. It had more down that its nest mate, and the unfeathered tract is not more than 



one-fourth the width seen in No. 1 1. No. 12 seems to me to represent the condition generally seen in domestic 

 pigeons, while No. I 1 is certainly a wide variation. In No. 12 the feathers come more smoothly together; they 

 are behind No. 1 1 in unfolding. 



( '. Same as A above, age 26 days, x 1. Wilson del., March 14, 1900. Hybrid No. 1 1 is now nearly 4 weeks old and 

 can fly. The unfeathered tract (between dotted lines) is represented as same width as before, but within this 

 pin-feathers are coining in, advancing from the sides toward the middle some of the outer ones just beginning 

 to unfold. The middle and wider portion of the tract still has only a few pin-feathers close to the older feathers 

 the central part for about an inch in length being still bare. Above and below this bare area the pin-feathers 

 have appeared (over the whole surface, though few in number), less advanced in middle than at sides. 

 D. Hybrid No. 12 has a smooth breast and a short crease above, about an inch in length, and shallow as compared 

 with No. 1 1. No. 1 2 is the larger bird, and though strong and robust is behind its mate in feathering; it can not 

 yet fly. 



than one, and is a little behind its mate in feathering, though strong and robust; 

 it can not yet fly. 



Two other hybrids of this same fraternity show the breast-crease. One of these 

 was of white color (text-fig. 26, fig. C), and the other (text-fig. 27, fig. A) was black. 



