558 Allen, Pattern Development in Teal. [oct 



of Upland Plovers there. Thus does man's activities play havoc 

 with the finest natural homes of certain species of birds. The 

 colony of Ravens, formerly located in the romantic Rocky Gap, 

 six miles east of Cumberland, was also no more. As if to miti- 

 gate this disappointment, however, I found on July 9, a family 

 of Blue Grosbeaks (Guiraca c. caerulea) on Knobley Mountain, 

 making at least one species, and that an interesting one, to be 

 added to the birds of western Maryland. 

 Oak Park, Illinois. 



PATTERN DEVELOPMENT IN TEAL. 



BY GLOVER M. ALLEX 



An article by Mr. Frederic H. Kennard in ' The Auk' for October 

 1919, describing and naming the Southern Blue-winged Teal 

 as a distinct subspecies, brings out a point of considerable evolu- 

 tionary interest, which it seems to me is worth emphasizing. The 

 chief mark of the newly recognized race is the presence of a white 

 superciliary stripe continuing the white crescent between the eye 

 and bill, characteristic of the common Blue-winged Teal, and the 

 two stripes, one on each side, meet at the back of the head and are 

 continued medially to form a white nuchal patch of varying extent. 

 This unusual extension of the white crescentic mark is found in 

 the adult males only and is characteristic of the completely de- 

 veloped nuptial plumage in the Southern birds. A similar, 

 though often irregular line, is sometimes seen in partially white 

 domestic pigeons and ducks. 



The formation of a definite pattern of pigmented (i. c, colored) 

 and pigmentless (i. c, white) areas, particularly in birds and 

 mammals, is a subject which has greatly interested me, and in an 

 article in the American Naturalist (vol. 48, p. 3S5-412, 467-484, 

 550-56G, 1914) I have endeavored to establish that in these two 

 classes of vertebrates, white markings when present tend to occur 

 in certain definite places. This is due to the fact that the surface 



