402 THE FUE SEALS OF THE PRHJILOF ISLANDS. 



walked up to a flock of about fifty, and with care could drive tliem before me for some 

 distance before they took fight, being but a few feet away. The females always pluck 

 out a patch of feathej's on each side of their underbody, and fully half of the males 

 collected had done the same, thus showing that they also had taken part in incuba- 

 tion. They are often seen feeding in the water up to their breasts, and seem to take 

 delight in it. They swim readily, but not often. On June 30, I saw one fly out to a 

 stone in a pool, and, after gathering all the food possible, it deliberately swam to 

 another, and having visited each stone in the same way, flew back to the shore and 

 then bathed itself, occasionally taking a swim. 



The downy young are beautiful little things, silvery white beneath, bright, rich 

 ocherous above, varigated with black and dots of white. The general color above 

 lacks the grayness of the similar age of maritimus. The white dots are interesting 

 under the microscope. They are composed of a bunch of highly specialized down, in 

 which the radii near the tip are crowded and colorless. Fig. 1 , PI. XL, shows a bunch 

 composed of six downs, and also a single component, 1, a. The ordinary down is shown 

 in Fig. 2 ; these surround each dot or bunch. As they grow older the first feathers 

 appear on the sides of the breast, on the back and scapulars; then the primaries and 

 larger wing coverts appear. Fig. 3 shows the down attached to the tips of the rami 

 of these new feathers, and the amount of wearing near their tips. In fig. 4 a tip of a 

 ramus is shown with a down attached; at a is seen the swelling mentioned under Uria 

 lomvia arra. The feathering continues until the breast and under parts are covered, 

 when the tail appears. At this time there are no feathers on the rump or on the head 

 or neck. In the next stage feathers have appeared on the occiput and on the auricu- 

 lars, and are also extending up the neck. At the same time the tips of the back feath- 

 ers have become somewhat worn, so that the colored margins are narrower and the 

 black more prominent. The wing coverts are also to some extent worn on their tips. 

 When the bill is an inch long the down has nearly all disappeared, and when it has 

 entirely gone the birds appear in small flocks on the beaches, the young generally 

 keeping together. Then another change takes place, for the entire plumage now gives 

 way to another, that in which the bird passes the winter. A few late July, immature 

 birds show the beginning, for No. 118832, im. S , July 29, has a few new feathers on 

 the middle of the back and on the scaj)ulars. They soon extend all over the back, so 

 that specimens collected up to August 10 have many of the new whitish feathers on 

 that region. The contrast is striking between these feathers, the latest being of an 

 almost even shade of pale plumbean with darker centers and generally with a narrow 

 white margin. There are no specimens to show the complete change, but it is prob- 

 able that these young birds remain on the island until it is completed. By the mid- 

 dle of June the adults have fully changed to the breeding plumage, but on some 

 specimens a few feathers of the previous winter's plumage persists much later. Thus 

 on many specimens some alternate feathers of the scapulars and tertials are of the 

 previous winter's well-worn plumage. In fact, few specimens are free from these old 

 feathers. Soon after the middle of July the new plumage of the next winter begins 

 to appear. At first a few feathers show about the breast, then on the scapulars, 

 thence up the neck and over the head, so that by the 10th of August they have 

 changed one-half. On No. 118764, July 12, the three shortest primaries and on No. 

 118787, same date, the foui' shortest have been dropped. The tips only of the new 



