ALCID.E — THE AUKS — SIMORHYNCHUS. 



513 



color of bill dull brownish. Young (= Uria dubia, Pallas) : Bill simple and smooth as in the 

 winter adult, but smaller ; plumage as in the adult, but crest and auricular filaments absent or but 



^^§^ 



Summer adult. 



slightly developed. Bill dull brownish. Total length, about 9.00 inches ; wing, 5.25 ; culmen, 

 .45 ; tarsus, 1.00 ; middle toe, with claw, 1.35. 



Judging from the very extensive series of specimens before us, it appears that the young gradu- 

 ally assume both the frontal crest and the white auricular filaments during the latter part of their 



first year, the peculiar character of the bill being gradually assumed at the approach of the breed- 

 ing-season. Perfectly adult birds apparently retain as permanent ornaments the curled frontal 

 crest and line of white acicular feathers across the auricular region ; lint after the close of the 

 breeding-season the basal horny parts of the bill (perhaps also of the entire bill, since the terminal 

 vol. ii. — 65 



