LARID^— THE GULLS AND TERNS. 223 



The species belonsring to eastern North America may be char- 

 acterized as follows : 



A. Adult with the entire head, neclc, lower parts, and tail pure white. (Larus, Linn.) 



II. Mantle very pale pearl-bliie; primaries the same, fading into white toward the ends. 



1. L. rlauous. WiuK, 16.75-18.1 inches; culmen, 2.15-2.65; depth of bill through the 

 ancle, .75-1.00; tarsus, 2.30-3.00; middle toe. 1.9.';-2.50. Eyelids in summer adult, red- 

 dish purple; feet flesh-color. 



2. I, leucopteruB. Wing. 15.10-16.50 inches; culmen. 1.65-1.00; depth of bill through 

 angle, .C0-.70; tarsus. 2.05-2.20; luiddlo toe. 1.70-1.95. Eyelids in summer adult. flesh- 

 color; feet inclining to orange-red. 



h. Mantle pale peai 1-blui' ; primaries similar, but abruptly tipped with white. 



3. 1. kumlieni. Five outer primaries marked with slate-gray spaces immediately be- 

 fore the white tips; color of the mantle as ini. /eucop/erws, and size about the 

 same. Eyelids in summer adult reddish purple, or purplish flesh-color; feet flesh- 

 color. Wing. Il>,00-17.00inrhe9; culmen, 1.60-1.90: depth of bill through angle ..5.5-66; 

 tarsus, 2.10-2.40. Hab. North Atlantic coast, breeding in Cumberland Sound, and 

 migrating south in winter to Nova Scotia, New Brunswick, and New York. 



c. Mantle dark slate-oolor, the primaries marked with black and white terminally. 



4. L, marinus. Wing, 17.60-19.50; culmen, 2. 40-2. 6»; depth of bill at angle; .98-1.05; 

 tarsus. 2.78-3.10. Hah. Coasts of the North Atlantic. 



d. Mantle some shade of bluish gray: primaries marked with black and white at and 



near the end. 



5. L. argentatns. Wing, 15.75-17.90 inches; culmen. 1.85-2.20: depth of bill through 

 angle. .70-.80; tarsus. 2.30-2.72; middle toe, 1.85-2.25. Mantle pale pearl-blue. Bill 

 deep yfllow, the mandible with red subterminal spot; eyelids yellowish; iris sil- 

 very white or pale yellow; legs and feet flesh-color. 



6. L. argentatus smithsonianug. Similar to true /,. argentalus, but averaging larger 

 and with less white and more black on primaries. Wing, 10.25-17.50; culmen, 1.95- 

 2.50; depth of bill through angle, .68-.85; tarsus. 2.30-2 80: middle toe. 1.85-2.25. 



7. 1. delawarensis. Mantle pale pearl-blue (much as in 7.. arsp/iiudtsi. Wing. 13.60- 

 1.5.75 Inches ; culmen, 1.55-1.75: depth of bill through angle, .50-.65; tarsus. 1.90-2.45; 

 middle toe, 1.30-1.60. Bill greenish yellow, crossed near the end by a blackish 

 band, the tip sometimes tinged with orange: eyelids vermilion-red; iris clear pale 

 yellow; legs and feet pale yellow, sometimes tinged with greenish. 



8. L. oanns. Mantle pale ashy blue (as in L. hrachyrhyncliua). Wing. 13.90-14.50 

 inches; culmen, 1.35-1.60; depth of bill through angle. .45-50; tarsus, 1.90-2.25; mid- 

 dle toe. 1,35-1.45. Bill greenish olivaceous (in the dried skin), the terminal third 

 yellow; eyelids vermllion-red; iris grayish brown; legs and feet yellowish green. 

 Hab. Palsarctic region ; accidental In Labrador? 



B. Adult with the head and upper part of the neck black or slaty in summer, forming a 



well deflned "hood :" plumage of the lower parts rose-tinted ; size medium to very 

 Bmi^ll; the bill slender. (Chroicocephalus, Eyton.) 

 a. Tarsus longer than the middle too and claw . 



9. L. atrioilla. Bill and feet dark brownish nrd. the former sometimes tipped with 

 brighter red; eyelids dull red; iris dark brown: hood dark sooty-slate: mantle 

 deep plumbeous- slate. Wing, about 13.00 inches. 



h. Tarsus shorter than the middle toe and claw. 



10. L. ftanklinil. Bill and feet oarmlne-rert; iris (lark brown; hood plumbeous-black ; 

 mantle deep bluish plumbeous. Wing, about 11.25 Inches. 



11. L, Philadelphia. Bill uniform dei-p black; legs and feet lino orange-red in summer, 

 )li'sh-c:olor in winter; iris dark brown; hood dark plumbeous; mantle delicate 

 pearl-blue; Wing, about 10.25 inches. 



12. L. m-nntus. Bill reddish dusky; legs and feet vermilion- or ooral-red; hood deep 

 black: mantle delicate poari-gray ; primaries without any block markings. Wing, 

 about 8.75-9.00 inches. Hab. Palsarctic Region; accidental in Ma.s8achu8utt8 and 

 Bermudas. 



