92 ORNITHOLOGICAL EXPLORATIONS. 



the nasal tubes and the nail, and the nasal tubes themselves are always 

 light-colored, never dark, much less any other part of the bill. The re- 

 verse is the case in the different forms of the Atlantic birds, in which 

 the nasal tubes seem to be dark-colored, and in a great many, if not 

 all, dark-colored individuals, the whole bill has a brown color. There 

 seems also to be a constant difference in the color of the iris of the two 

 races, as it is given as yellow for the old Atlantic bird, while in the Pa- 

 cific variety itis invariably dark brown, although it should be stated that 

 Faber describes the Icelandic birds as haviug the irides ^^nigro fusciP 

 The accounts of the exact colors of the light parts of the bill in the 

 Atlantic birds are very uncertain and unsatisfactory. In the Pacific 

 race I found two very different styles of color of the bill. All those 

 which I examined at the breeding places, whether dark or white, had a 

 whitish bill with faint bluish, greenish, and pinkish shades, conse- 

 quently a kind of mother-of-pearl color. A faithful picture was pre- 

 pared by me from a fresh specimen and is reproduced as fig. 2, on pi. 

 vi, giving an exact representation of the color as it was invariably found 

 in the adult breeding birds from early spring until August, at least, 

 when I observed the last ones. The other style is represented in fig. 

 1, pi. vi, also colored from the fresh specimen, an old white bird from 

 Bering Island, obtained in February. The bill is absolutely yellow 

 with tinges of greenish and orange brownish. As this was the only 

 winter bird I got, I cannot say whether this difference in the colors of 

 the bill is due to season, but I really suspect it is, as I saw none among 

 the thousands and thousands of summer birds with yellow bill, although 

 I had excellent opportunity for observation, and I paid a special and 

 careful attention to the subject, as will be seen. Most of the Atlantic 

 observers record the color of the bill as yellow ; is that not due to the 

 fact that they had winter specimens before them ? Faber, one of the 

 most conscientious observers, describes the color of the bill of the Ice- 

 landic bird (in summer plumage, as he only got a few winter specimens) 

 as being " grisescens, dertro aduuco flavesceuti. * * * nares * * 

 * nigrse." (Beytr. Arct. Zool., II, Isis, 1824, p. 78G), which seems to con- 

 firm my opinion of a seasonal change in the color of the bill, as Nau- 

 manu, a not less careful observer, describes the bill of the old bird as 

 beautiful and rich yellow with the nasal tubes slaty black, he having 

 probably had only winter birds taken off the coast of Germany (Naturg. 

 Vog. Deutschl., X, p. 594: " Der Schnabel * * * an seinem gros- 

 sen Haken und dem Spitzentheil desUnterschnabels sehr schon hoch- 



