556 



THE AMERICAN NATURALIST [Vol. XLVIII 



during a white throat, and as sometimes in the pigeon, 

 imperfectly, so that a little island of pigment is cut off 

 just at the chin. It is also obvious from these figures, 

 that reduction may take place either at one end or the 

 other, or at both ends in different individuals. The ulti- 

 mate development of this line of reduction will produce 



the narrow black collar seen in Xetfapus previously men- 

 tioned. It is worth noting also that in this goose the 

 limits of the neck patch are by their black color sharply 

 denned posteriorly from the gray of the breast which is 

 pigmented from the shoulder patches. 



The Shoulder Patches. — The shoulder patches appear 

 to center near the base of the wing, and in reduction 

 produce white remiges, such as appear in a domesticated 

 race of guinea fowl, as well as a white breast. The 

 domesticated guinea fowl often shows this white area in 

 the midline of the breast as the pigment areas fail to 

 spread ventrally. In the normal pattern of wild birds, 

 however, white wings are seldom seen except among cer- 

 tain sea birds. White wing patches are often developed, 

 but these are frequently only bars on pigmented feathers 

 as in the goat-suckers. Probably among small land birds 

 much white in the large wing feathers is a disadvantage, 



