22 PROCEEDINGS OF THE ACADEMY OF 



bus angustissime et perpendieulariter compressis, cutis callosa dura iu basi 

 mandibuli superioris. Ad supercilia cornu breue," etc. 



Coasts and Islands of the North Atlantic, very abundant. Rare in the North 

 Pacific, (Pallas,) where replaced by F. corniculata. In winter, south on the 

 American Coast to Massachusetts. Breeds on the islands in the Bay of Fundy, 

 (Boardman). Numerous specimens in all American Museums. 



Adult {breeding plumage.) — Iris hazel brown. Eyelids vermillion red, the 

 fleshy callosities bluish ash. Base of bill and first ridge dull yellowish, the 

 smooth contained space bluish, rest of bill vermillion red, the tip of the lower 

 mandible and the two terminal grooves yellowish. Legs and leet coral red, 

 claws black. Crown of head grayish black, the edges of which are sharply 

 defined against the color of the sides of the head, chin and throat, and the pos- 

 terior edge of which is separated by a very narrow but distinct transnuchal 

 stripe of ashy from the color of the back. Sides of head, with chin and 

 throat ashy white ; nearly white between the eyes and bill, and with a max- 

 illary stripe or area of blackish ash on either side of the throat. A narrow, 

 distinct line of white along the anterior edge of the antibrachium. Entire 

 upper parts glossy black, with a bluish lustre, continuous with a broad collar 

 of the same around the sides and front of the neck. Under parts from the 

 neck pure white, the elongated feathers of the flanks and sides blackish. Under 

 surface of wings pearly ash-gray ; inner webs of primaries and secondaries 

 dull gray-brown, the shafts brown, blackish at tip and whitish towards the 

 base. 



Length 13-50, extent 24-00, wing 6-50, tail about 2-25 ; tarsus I-OO ; middle 

 toe 1-40, its claw -40 ; outer toe 1-40, its claw -30 ; inner toe 1 -00, its claw -40 ; 

 bill — chord of culmen 2-00, its curve 2-10; depth of bill at base 1-40; rictus 

 1-25; gonys 1-45: greatest width of bill (which is at base of nostrils) -60; 

 length of nasal slit -35. 



Young. — Bill much smaller and weaker than in the adult ; without the basal 

 ridge, and with onlj' slight indications of the warty callosities at angle of ric- 

 tus ; the terminal grooves wanting, or faintly indicated ; the culmen much 

 less convex ; the gonys convex and ascending posteriorly, without the sharp 

 hamular process at base. Such are the general characteristics of the young, 

 thouo-h full-grown bird. Birds not grown have their bill much smaller still, 

 entirely without grooves or ridges, acute at the apex, the culmen and gonys 

 perfectly straight ; the lateral aspect of the bill is almost an equilateral trian- 

 gle. Bill basally blackish ; terminally yellowish. Legs and feet reddish yellow, 

 obscured with dusky. The eyelids want the fleshy processes. In colors of 

 plumage the young birds are almost exactly like the parents, except that the 

 ashy of the sides of the head is tinted with sooty black, more or less directly 

 continuous with the black of the crown, and lightening into a dusky ash on 

 the auriculars and lower parts of the sides of the head. 



Nestlings are covered with blackish down, becoming whitish on the under 

 parts from the breast backwards. 



This species presents little variation in any respect from the conditions as 

 above described. The dimensions do not vary much, and even the bill is very 

 constant in size, shape and colors. The plumage of the adults scarcely pre- 

 sents appreciable variation. 



The protuberance on the lower eyelid is horizontal, and occupies the whole 

 leno-th of the lid. That on the upper ej'elid is nearly perpendicular, and 

 higher than broad ; but is short, obtuse and never developed into an acute 

 process. 



There is absolutely no difference between American and European speci- 

 mens. The footnote on page 251, Pr. A. N. S. Phila. for 1861, is to be can- 

 celled as wholly erroneous. 



No bird of the familj' oi Alcidse is better known than the present species. It 

 is the type of the Linnaean genus Alca of 1744, but not of 1758, nor of subse- 



[Jan. 



