° 1920 J Allen, Pattern Development in Teal. 56o 



death occurred shortly after, in April of that year. This interest- 

 ing case only serves to emphasize still further that this "necktie" 

 pattern is a newly acquired character in the phylogeny of the race, 

 and in the growth of the individual is assumed at the time of its 

 highest physiological development. The fact that the captive 

 bird finally lost this marking may have been due to impaired vigor, 

 either as a result of old age or as a result of the abnormal condi- 

 tions of captivity, which as is well known, nearly always result 

 in interrupting the usual course of physiological processes. If due 

 to senescence, it is paralleled by numerous other cases in both 

 vertebrates and invertebrates. A familiar one is the "going 

 back" of deer antlers in old males. 



The Southern Teal is not the only duck that might be cited as a 

 case of formation of a distinct geographical race through the 

 differential development of white areas in the plumage by res- 

 triction of pigmentation. Mr. Outram Bangs has called my 

 attention to the case of the Teals of the Andaman Islands, Pol- 

 ionctta albigiilaris, in which (Fig. 4) the ventral side of the throat 

 and a spot just below the eye are white, showing thus only a slight 

 restriction of the ear patches ventrally and about the eye. In one 

 of two specimens from the same locality, however, white feathers 

 appear at the base of the bill, and the white mark below the eye 

 is much larger than in the other, indicating that the pattern is still 

 in an unstabilized condition. The development of white areas 

 thus begun, is carried still further in the race P. a. leucopareus 

 from North Reef Island, in the same group, in which the restrict- 

 ion of the ear patches is so extensive (Fig. 5) that the upper throat 

 and side of head to the level of the eye are white as far back as the 

 ear opening, and a white collar has resulted through failure of the 

 ear patch to reach the upper edge of the neck patch. Behind the 

 ear, the crown patch is still united with the ear patch except at 

 the occiput, where a very small white spot occurs in one of the 

 two specimens seen. One might conceive of a further stage in 

 evolution of this pattern, whereby the crown patch would persist 

 intact, but the ear patches dwindle perhaps to a very small spot 

 over the ear opening. Such a pattern is found in the Old-squaw 

 female in winter. A subsequent loss of the crown patch would 

 then leave a head pattern similar to the adult male Old-squaw. 



