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THE AMERICAN NATURALIST [Vol. XLYIII 



divide medially. Probably for some reason the forma- 

 tion of the pigment is more intense at the sides of the 

 crown than in the center where the nerve and blood 

 supply is less. In the pterylosis of this area the develop- 

 ment of feathers is seen to be greater at the sides also. 



The neck patches and the side patches are absent en- 

 tirely, but the shoulder patches are both present, in Fig. 

 56, that of the right side covering the scapulars and 

 middle of the upper back, that of the left side including 

 a few only of the scapulars. 



The tail patches are both present, and separate from 

 each other, as shown by the median white rectrices. 



In this same flock of mallards was a female which had 

 a white ring at the base ofthe neck in the same situation 

 as the white ring which in the male is a part of the per- 

 manent pattern. It was not quite complete dorsally, 

 however, in this female, and was somewhat broader than 

 regularly in the male. Nevertheless, it is apparent that 

 this white collar in the male is merely a primary break 

 between neck and shoulder patches that has become 

 developed as a part of the normal pattern. 



Stone (1912, p. 318) in his paper on the phylogenetic 

 value of color characters in birds, hints at the existence 

 of these patches. He says, in part : 



In matters of pattern there seems to be a deeper problem involved, 

 i. e., the determination of the cause -mem in- the appearance of a d it- 

 belonging to wholly different groups ... or the presence of a mystacial 

 stripe, a superciliary stripe, a light rump patch. ... In fact if a bird 

 exhibits a bright or contrasting patch of color, it is, in the vast major- 

 ity of cases, found on one of several definite portions of the plumage, 



These contrasting areas are due to the develop 

 one or more of the primary patches, or of breaks * 

 them, or again paler areas, as at the bend of the 

 on the rump, indicate often a lessening of pigment inten- 

 sity at a distance from the respective primary centers. 



(To be concluded.) 



