NORTH AMERICAN BIRDS. 



d\ Wing 16.25 or more, and not more than 2.3G times as long as the 



tail; exposed culmen 1.88 or more. Adult in summer : Mantle 



very pale pearl-gray. Adult in winter: Similar, but head and 



neck streaked with pale brownish gray. Young : Grayish 



white, tinged with brownish gray on lower parts, the upper 



parts transversely mottled with same. Immature (second 



year f) : Entirely white, including mantle and primaries. 



Downy young : Graj'ish white, paler below ; head and neck 



irregularly marked with scattered large spots of dusky, the 



back, wings, and rump irregular!}- clouded with dark graj-ish. 



e'. Length 26.00-32.00, wing 16.75-18.75 (17.99), tail 7.40-8.50 



(8.07), culmen 2.30-2.70 (2.52), depth of bill through angle 



.80-.95 (.88), through base .83-1.00 (.93), tarsus 2.60-3.05 



(2.85), middle toe (with claw) 2.68-3.00 (2.84). Eggs 



3.13 X 2.14. Hab. Coasts of the North Atlantic, and 



Arctic seas from Cumberland Gulf to Spitzbergen ; south, 



in winter, to Long Island and the Great Lakes. 



42. L. glaucus Brunn. Glaucous Gull. 



e'. Length about 25.00-28.00, wing 16.25-18.00 (17.12). tail 7.00- 



7.50 (7.28), culmen 1.88-2.30 (2.06). depth of bill through 



angle .72-.85 (.79), through base .70-.80 (.75), tarsus 2.40- 



2.78 (2.57), middle toe (with claw) 2.35-2.75 (2.55). Eggs 



3.05 X 2.03. JEab. Bering's Sea and adjacent waters, 



northeastward to Point Barrow, southwest (in winter) to 



Japan... 42.1. L. barrovianus Eidgw. Point Barrow Gull. 



a". Wing not more than 17.00 (usually less than 16.00), and nearly 



2.50 (averaging 2.41) times as long as the tail ; exposed culmen 



not more than 1.70. In plumage exactly like E. glaucus and 



E. barrovianus. 



Length 24.00-26.00, wing 14.75-16.50 (15.41), tail 6.00-6.70 

 (6.41), culmen 1.60-1.70 (1.67), depth of bill through angle 

 .62, through base .55-.62 (.59), tarsus 2.10-2.40 (2.22), mid- 

 dle toe (with claw) 2.10-2.35 (2.21). Eggs 2.79 X 1-89. 

 Hab. Coasts of the North Atlantic; south, in winter, to 

 Massachusetts and the Groat Tvukes. 



43. L. leucopterus Faber. Iceland GnlL 

 Primaries marked wilh distinct white tips and darker subterminal 

 spaces. 

 dK Darker spaces of primaries gray. 



e'. Second quill very pale pearl-gray, or bluish white, very broadly 

 tipped with white, the outer web with an elongated s])ace 

 of graj', everywhere very sharply defined against the paler 

 ground-color. 



RiDOW., .\uk, iii. July, 18S6, 330. 



