246. Zoological N. Y. Zoological Society. [I; 12 



The two gular patches had increased in size and intensity of 

 color. 



On the fifty-sixth day the pale band had disappeared from 

 the lower mandible, but was still discernable on the upper. A 

 new area of pale color had now appeared at the tip of the up- 

 per mandible. 



About a month later, when the young bird was eighty-three 

 days old, the pale terminal area on both mandibles had spread 

 backward, so that the anterior half of the beak was then a 

 clouded pinkish. The basal half was not as black as in the 

 young chick. Ten days later the pinkish area had reached the 

 second of the congenital pale zones, and the skin around the 

 eye had become distinctly pink. 



In the six months' old bird the bill was wholly of a clouded 

 pink color, very much lighter than in the adults. The bare face 

 was pale flesh color. The iris at this age was pale slate blue, 

 with a narrow inner ring of hazel. 



Recorded measurements in millimetres are as follows: 



Length. Culmen. Wing. Tail. Tarsus. 



3-day chick 150 19 29 22 



23-day chick 230 37 60 23 55 



2-months' juvenile 450 65 235 90 75 



18-months' bird 625 158 286 100 92 



Fully adult bird 675 168 290 106 100 



I have kept a record of the pigment producing possibilities 

 of the feathers of a young growing White Ibis. The feathers of 

 the juvenile tail are uniform only in that the terminal half is 

 brown, and the basal half white. The zone of darker color is 

 not constant, and in the twelve feathers of any individual no 

 two may be alike, while the white area may be immaculate, or 

 variously clouded or mottled, especially on the outer web, with 

 brown pigment. A feather may appear, which on the terminal 

 half, is solid brown on the inner, broader web, while the outer 

 is pure white, the line of demarcation here being the shaft, but 

 this is exceptional. Having in mind that it is upon such varia- 

 tions in feathers that the theory of color-change in the dead 

 feather has been chiefly based, I applied the only possible proof, 

 and by marking feathers such as the last, ker)t them under con- 



