LARID.E THE GULLS AND TERNS. 223 



The species belonging to eastern North America may be char- 

 acterized as follows: 



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



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



1. L. plaucus. Wing, 16.75-18.fiO inches ; culmen, 2.15-2.65; depth of bill through the 

 angle, .75-] .00 ; tarsus, 2.30-3.00 ; middle toe, 1.95-2.50. Eyelids in summer adult, red- 

 dish purple; feet flesh-color. 



2. L. leucopterus. Wing, 15.40-16.50 inches; culmen, 1.65-1.90; depth of bill through 

 angle, .60-.70; tarsus, 2.05-2.20; middle toe, 1.70-1.95. Eyelids in summer adult, flesh- 

 color; feet inclining to orange-red. 



b. Mantle pale pearl-blue ; primaries similar, but abruptly tipped with white. 



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

 fore the white tips ; color of the mantle as in L. leucopterus, and size about the 

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

 color. Wing, 15,00-17.00 inches ; culmen, 1.60-1.90 ; depth of bill through angle .S5-.66 ; 

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

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



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



4. L. marinus. Wing, 17.60-19.50; eulmen, 2.40-2.60; depth of bill at angle; .98-1.05; 

 tarsus, 2.70-3.10. Hob. 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. argentatus. 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 yellow, the mandible with red subterminal spot; eyelids yellowish; iris sil- 

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



6. L. argentatus smithaonianus. Similar to true L. argentatus, but averaging larger 

 and with less white and more black on primaries. Wing, 16.25-17.50; culmen, 1.95- 

 2^0; depth of bill through angle, .68-.8S; tarsus. 2.30-280: middle toe, 1.85-2.25. 



7. L. delawarensis. Mantle pale pearl-blue (much as in L. argentatus^. Wing, 13.60- 

 15.75 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. canus. Mantle pale ashy blue (as in L. brachyrhynchus). Wing, 13.90-1450 

 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 vermilion- red; iris grayish brown; legs and feet yellowish green. 

 Sab. Palsearctic region ; accidental in Labrador ' 



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



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

 small; the bill slender. (Chroicocephalus, ETTON.) 

 a. Tarsus longer than tho middle toe and claw. 



9. L. atritsilla. Bill and feet dark brownish red, 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. 



6. Tarsus shorter than the middle toe and claw. 



10. L. franklinii. Bill and feet carmine-red; iris dark brown; hood plumbeous-black; 

 mantle deep bluish plumbeous. Wing, about 11.25 inches. 



11. L. phfladelphia. Bill uniform deep black ; legs and feet fine orange-red in summer, 

 flesh-color in winter; iris dark brown; hood dark plumbeous; mantle delicate 

 pearl-blue: Wing, about 10.25 inches. 



12. L. minntus. Bill reddish dusky; legs and feet vermilion- or coral-red; hood deep 

 black; mantle delicate pearl-gray; primaries without any black markings. Wing, 

 about 8.75-9.00 inches. Hab. Palzearctic Region; accidental in Massachusetts and 

 Bermudas. 



