158 CALIFORNIA ACADEMY OF SCIENCES  [Proc. 4ra Ser. 
and exposed definitive feathers dominate the pileum. The 
lower tail-coverts have appeared, definitive feathers have in- 
vaded the posterior cervix, and the throat and sides of head are 
being clothed. No. 517, female, manifests further progress. 
The wings and tail are beginning to be visible through the natal 
down, the region below the eyes and the sides of the body are 
covered with definitive feathers, and the axillaries and under 
coverts of the wings have broken from their sheaths. In No. 
516, female, growing definitive feathers hide the skin on the 
throat and lores, and the wings and tail have lengthened and 
are freer from down. No. 515, male, has thrown off most of 
the natal down. The abdomen, however, is still hidden by it, 
and conspicuous remnants adhere to the occiput and cervix. 
No. 514, male, still carries some remains of natal down on the 
occiput, lower breast, abdomen, and under tail-coverts. The 
outer webs of the longer tertials are silvered with gray and 
edged with grayish white. In all the specimens the natal down 
is mouse gray, darkest in tone on the concealed secondary 
down. 
The twenty-eight adult Expedition specimens were taken as 
follows: Three on the 4th and 5th of January; fifteen on the 
8th, 9th, and 10th of May; four on the 16th and 18th of June; 
five at the breeding station on the 13th of August; one on the 
Oth of November. Although very deficient, this series sheds 
some light on the moult. Four of the fifteen May specimens 
have slight and irregular feather growth in progress, involving 
a rectrix in one instance. In two of the June specimens upper 
tail-coverts are being replaced. Three of the August specimens 
are renewing upper tail-coverts and a fourth two rectrices and 
some of the under tail-coverts and a little of the body plumage. 
The November specimen is replacing a rectrix and feathers on 
the breast and abdomen and in the lower tail-coverts. In the 
January specimens renewal is apparently quiescent. 
