34 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4TH SER. 
to different orders. In the preparation of part VI of the pres- 
ent paper, I have studied the moult in over two thousand speci- 
mens of albatrosses and petrels. This series, however, was 
collected without reference to moult, and in consequence is 
deficient in many respects. Specimens taken from day to day 
and studied in the flesh would have yielded far better results. 
In some species at least, the postnuptial moult of the Tubi- 
nares begins before the birds leave their nesting grounds, as 
in the Galapagos Albatross and Townsend’s Shearwater. Of 
the duration of this moult in individuals, I have no definite 
information, but in certain species, as in the Sooty Shearwater, 
I have found it protracted over most, if not all, of the year. 
Throughout its course very different stages are manifested in 
specimens of the same species taken on the same day. This 
diversity is accounted for in part by the fact that the individ- 
uals of Tubinarine species differ to a greater or less extent in 
the time of their breeding, even in temperate regions. As no 
two birds are exactly alike, it is self-evident that moulting in 
any species must vary more or less in different individuals 
independent of their age, the state of their health, or the time 
of their breeding. 
Owing to the protraction of the postnuptial moult period, I 
have been unable to determine positively from the material at 
my command whether there occurs or not a limited prenuptial 
or a deferred limited postjuvenal moult. It is apparent that 
the Tubinares offer a most inviting field for moult study. 
Wear of Plumage.—The changes wrought by fading and 
abrasion are so great in the Tubinares that the descriptions of 
certain species are incomplete unless they describe both worn 
and fresh plumages. Through wear, deep brown becomes 
decidedly paler, as in the Antarctic Fulmar’; dark gray browns, 
as in the Sooty Shearwater; washing or frosting vanishes, 
unvailing a darker color, as in Cook’s Petrel; blooms fade, as 
in the storm petrels; light tips are lost, causing uniformity in 
coloration, as in the Mottled Petrel; dark tips disappear, some- 
times exposing basal white and enlarging white areas, as in 
the Black-footed Albatross. Even before the postnuptial moult 
ends, the destructive changes in the new plumage are apparent, 
as in Cooper’s Shearwater. Obviously, specimens taken at 
1 Wilson, Nat. Antarct. Exp., N. H., v. 2, Aves, p. 83. 
POE NTI NS aE ee SI 
