242 Zoologica : N. Y. Zoological Society. [I ; 12 



have not observed a reverse case of feeding. The eggs are laid 

 in June, usually about the first week, and the time of incubation 

 lies between twenty and twenty-three days. Both parents take 

 part in feeding the young. The comminuted fish is brought in 

 the gular sac which is developed in both sexes. The male, owing 

 to the enlargement of the chin sac, is able to pack much more into 

 his throat than his mate. When one of the old birds comes to 

 the nest with food, the bill is opened widely and the young Ibis 

 reaches up and takes the food from the throat of the parent. 

 The sight of this feeding process is contagious and I have seen 

 unmated ibises moved to fly up with offerings of food, and even 

 the young bird of the preceding year makes similar attempts. 

 All are hustled away by the parents, however, before they have 

 had even a chance to carry out their altruistic efforts. 



II. Development and Annual Changes. 



For several years one or two pairs of White Ibis, Guara 

 alba (Linnaeus), have bred in the flying cage of the New York 

 Zoological Park. Usually two eggs are deposited but only a 

 single bird in each brood is reared to maturity. In 1912, a 

 young Ibis was hatched on July 6th, and another in a second 

 nest, about a month later. The desire to have this species estab- 

 lished as a regular annual breeder in the Park has led me to 

 leave the birds almost wholly undisturbed, but it was found pos- 

 sible during the present year to make a number of new observa- 

 tions, and the necessary handling of the nestling did not inter- 

 fere with the faithful care of the parents, who were able suc- 

 cessfully to rear the young bird. 



No definite description of the sequence of plumages in the 

 White Ibis has ever been written, as far as I have been able to 

 discover, and knowledge of the time of attainment of the fully 

 adult plumage is equally vague. In many ways Audubon's ac- 

 count is not reliable. 



The nestling in down plumage reveals a number of inter- 

 esting characters. At the time of hatching, the pterylosis of 

 the bird shows a very advanced development of down on the an- 

 terior portions. Thus the head, neck, upper breast and anti- 



