Vol. XXXVIII 

 1920 J 



Allen, Pattern Development in Teal. 



561 



does each spotted individual differ in the extent of its pigmented 

 areas, but corresponding areas of opposite sides vary in the amount 

 of reduction in the same individual, so that often the contiguous 

 patches of one side may show a white break between them, while 

 those of the opposite side retain contact. 



Figure 2. — Head of Blue-winged Teal, to show pattern. In this and 

 the other heads, the approximate outline of crown patch and the boundary 

 between ear and neck patches, are shown by a heavier dotted line. 



Figure 3. — Head of Southern Teal, showing extension of white pattern 

 through restriction of ear patch dorsally and posteriorly. 



Figure 4. — Andaman Teal (Polionetta albigularis) showing slight re- 

 duction of ear patch. 



Figure 5. — White-cheeked Andaman Teal (P. a. leucopareus) showing 

 incomplete formation of a white collar by failure of ear patch to meet the 

 upper end of neck patch. 



But to return to the Teal, the point of interest is that the white 

 crescentic mark of the normal bird is due according to this view, 

 to a restriction of the ear patch (whose ultimate center is the aural 

 region) at its front end, so that a pigmentless area is left at the 

 base of the bill (Fig. 2). The head pattern of the common Blue- 



