FAMII.Y LAIilD^. GULLS AND TERNS. 



39 



Section 2. Length, over 21; bill, over 2; underparts, 



not white. 



Outer webs of primaries, ash color (immature) . 



Lams glaucus. Glaucous QuII. 



See Xo. 24. 



Outer webs of pritnaries, dark browu; wihg, over 17. .50; depth of bill at angle, over .90 

 (immature). Lams mar hms. Great Black-backed Gull. 



See No. 27. 



Outer webs of primaries, dark brown; depth of bill at angle, under .90; wing, under 17. .50 

 (immature). Lams anjentatus smithsonianus. American Herring Gull. 



See No. 30. 



Section 3. Length, over 21 ; bill, under 2 ; underparts, white. 



Back, grayish blue, more or less black on primaries. 



Larus argentatus smithsoniamis. American Herring Gull. 



See Xo. 30. 



Back, pale pearl color; pri- 

 maries, whitish or pearl color, 

 shading to white at tips. 



Lams leurDptrrns. 

 Iceland Gull. 

 See X'^o. 2.5. 



RiDg.billeil Gall. 



Back, pale pearl color; primaries 

 marked with slat_y gray. 



Lams kumlie,ni. Kumlien's Gull. 



See No. 2G. 



Hcniii^' Gull. 



