BIEDS OF JSrORTH AND MIDDLE AMEEICA. 783 



by a backward prolongation of the culmen, the posterior end of 

 which meets the upper portion of the basal lamina, the posterior 

 half of which is minutely punctulated; a conspicuous tumid rosette 

 surrounding rictus; eyelids with deciduous horny plates, that on 

 upper eyelid in one species erect, hornlike. Wing moderate, the 

 longest primary (outermost) exceeding distal secondaries by slightly 

 more than half the length of wing. Tail less than one-third (but 

 more than three-sevenths) as long as wing, very slightly rounded; 

 rec trices 16. Tarsus much shorter than middle toe without claw, 

 the acrotarsium with a narrow series of small transverse scutella 

 on lower half or more; outer toe (without claw) slightly shorter 

 than middle toe (without claw), the inner toe (without claw) slightly 

 shorter than first two phalanges of middle toe, its claw conspicu- 

 ously larger, more strongly curved, and more acute than other claws. 



Nuptial ornaments. — Basal portion of bill with eleven deciduous 

 pieces, which are shed after the breeding season,'^ as are also the 

 horny appendages to the eyelids and the tumid rictal rosette. 



Plumage and coloration. — Xo ornamental head plumes. Upper 

 parts, together with a band across foreneck, imiform black, the 

 pileum grayish brown; sides of head grayish or white (blackish 

 anteriorly in winter) ; under parts of body immaculate white. 



Range. — Circumpolar regions, south in winter to Massachusetts, 

 Canary Islands, Queen Charlotte Islands, and Kuril Islands. (Two 

 species.) 



KEY TO THE SPECIES AND SUBSPECIES OF FRATERCULA. 



a. Deciduous nasal cuirass occupying less than basal half of bill; grooves on sides of 

 maxilla and mandible very oblique, broad, and distinct; process on upper eye- 

 lid short, subcorneal; nuptial plumage with upper throat gray (whitish gray 

 posteriorly, light mouse gray anteriorly and laterally) and sides of head light 

 gray posteriorly; tail shorter (42-53 mm.). (Fraierculn arctica.) 

 b. Smaller, with relatively smaller and narrower bill; averaging vnng, 162.9; tail, 

 48.4; culmen, 48.9; greatest depth of bill, 36.3; tarsus, 26.4; middle toe, 37.4. 

 (Coasts and islands of northern Atlantic Ocean, including Iceland and 

 southern Greenland, south in winter to Massachusetts, Portugal, Canary 



Islands, etc.) Fratercula arctica arctica (p. 784). 



bb. Larger, with relatively larger and deeper bill; averaging wing, 176; tail, 52.2; 

 culmen, 53.7; greatest depth of bill, 44.7; tarsus, 28.5; middle toe, 42.5. 

 (Islands of Arctic Ocean, from northern Greenland to Spitzbergen.) 



Fratercula arctica naumanni (p. 788). 

 aa. Deciduous nasal cuirass occupying much more than basal half of bill; grooves on 

 sides of maxilla and mandible nearly vertical, narrow and indistinct; process 

 on upper eyelid elongated, hornlike; nuptial plumage with whole throat 

 blackish, the chin, only, gray; sides of head white; tail longer (60-68 mm.). 

 (Shores and islands of northern Pacific Ocean and Bering Sea, from British 

 Columbia to Kuril Islands) Fratercula corniculata (p. 789). 



a See Bureau, Bull. Soc. Zool, de France, ii, 1877 (1878), 1-21, pis. 4, 5; Stejneger, 

 Bull. U. S. Nat. Mus., no. 29, 1885, 48-51, the latter with special reference, however, 

 to Lunda cirrhata. 



