558 



PATAGONIAN EXPEDITIONS! ZOOLOGY. 



The sexes do not vary in size; there is much individual variation 

 however. 



Color. Adult male cited above. Adults of either sex are alike when 



in adult plumage. 



FIG. 278. 



Polyborus plancus, adult male. P. U. O. C. 7894. About one-fourth natural size. 



Head : A crested cap reaching from the base of the bill, above the eyes 

 backward to the occiput, where the feathers are elongated, dark seal-brown ; 

 region in front of the eyes, and sides of the face pale isabelline, sometimes 

 almost buffy white. 



Neck : Pale isabelline or buffy white ; immaculate on the throat, and 

 barred with dark seal-brown barring elsewhere, the barring giving more 

 prominence to the dark than to the light color. 



