COMMON GUILLEMOT 487 



in winter in the North Pacific Ocean, where a form with 

 a stronger beak is to be found. It also frequents the seas 

 of Europe in winter, and small numbers occasionally occur- 

 in the Mediterranean. 



DESCRIPTIVE CHARACTERS. 



PLUMAGE. Adult male nuptial. Top of head, hind- 

 neck, back, scapulars, and wings, shading from greyish to 

 brownish-black ; cheeks, chin, throat, and fore-neck, dark 

 sooty-brown ; secondaries, brown, tipped with white, form- 

 ing a short, narrow wing-bar ; primaries, greyish-black with 

 paler inner webs; tail (of 12 feathers), brownish-black; 

 lower fore-neck, breast, abdomen, under tail- and wing- 

 coverts, white; flanks, white streaked with grey. 



Adult female nuptial. Similar in plumage to the male. 



Adult winter, male and female. Chin, throat, fore- 

 neck, and cheeks, white ; sides of head behind the eye also 

 white, bounded below by a narrow post-ocular dark greyish- 

 black band. 



Immature, male and female. Resembles the adult winter- 

 plumage, except that the white on the sides of the head and 

 fore-neck is mottled with dusky-brown. 



BEAK. Blackish, lighter at the base of the lower segment. 



FEET. Dark brownish-black behind and on both sides of 

 the webs ; front of the tarso-metatarsus and toes, brownish- 

 white. 



IRIDES. Brownish-black. 



AVERAGE MEASUREMENTS. 



TOTAL LENGTH ... ... 18 in. Female smaller. 



WING 7-5 



BEAK 1-9 



TARSO-METATARSUS ... 1*5 ,, 

 EGG 3-25 x 2 in. 



Allied Species and Representative Forms. The Einged 

 or Bridled Guillemot is not a distinct species, and inter- 

 mixes with thousands of the Common form. It is so named 

 because its eyelids are margined with white, and there is a 

 white stripe in the furrow behind them. 



