26 NORTH AMERICAN BIRDS. 



d'^. Wing 16.25 or more, and not more than 2.36 times as long as the 



tail; exposed culmen 1.88 or more. Adult i?i sununer : 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 ?) : Entirely white, including mantle and primaries. 



Downy young : Grayish white, paler below ; head and neck 



irregularly marked with scattered large spots of dusky, the 



back, wings, and rump irregularly clouded with dark grayish. 



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 olaw) 2.68-3.00 (2.84). IJggs 



3.13 X 2.14. Ifab. 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 BRtJNN. 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. Hab. Bering's Sea and adjacent waters, 



northeastward to Point Barrow, southwest (in winter) to 



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



d''. 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 L. glaucus and 



L. 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 Great Lakes. 



43. L. leucopterus Faber. Iceland GulL 

 c^. Primaries mai"ked with distinct white tips and darker subterminal 

 spaces. 

 d^. 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 space 

 of gvay, everywhere very sharply defined against the paler 

 ground-color. 



' Larua barrovianus Eidgw., Auk, iii. July, 1886, 330, 



