LARID.E— THE GULLS AM) TERNS. 223 



The species belonging to eastern North America may be char- 

 acterized as follows : 



A. Adult with the entire head, neck, lower parts, anil tail pun' white. (Lams, LlNN.) 



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



1. L. tlaueus. Wing, 16.75-18.f0 inches; culmen, 2.15-2.65; depth of lull through the 

 angle, .75-1.00; tarsus, 2.30 3.00; middle toe, L.95-2.50. Eyelids in summer adult, red- 

 dish purple; feel 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.ffesh- 

 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 he- 

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

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

 color. Wing, 15,00-17.00 inehes; culmen, 1.60-1.90; depth of hi!! through angle ,55-.66; 

 tarsus, 2.10-2.40. JIab. North Atlantic coast, breedingin Cumberland Sound, and 

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



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



4. L. marinus. Wing. 17.60-19. 50; culmen, 2.40-2.60; depth of bill at angle; .98-1.05; 

 tarsus, 2.70-3.10. llah. Coasts of the North Atlantic. 



(I. 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 subtermina] spot; eyelids yellowish; iris sil- 

 very while or pale ..riiow; legs and feel flesh-color. 



•*>. L. argentatus smithsonianus. Similarto true /-. argentatus, but averaging larger 

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

 2.50; depth of bill through angle, .68-.85; tarsus. 2.30-280: middle toe.l 



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

 15.75 inches; culmen, L.55-1.75; depth of bill through angle, .50-.65 ; tarsus, I, 

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

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

 yellow; legs an> inged with greenish. 



8. L. canus. Mantle pale ashy blue [as in I., brachyrhynchus). Wing, 13.90-14.50 

 inehes; 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 feel yellowish green. 

 Hab. Pal ■ii.ii ; accidental in Labrador? 



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



well deti ned "hood;" plumage of the lower parts rose-tinted; size medium b 

 small; the hill slender. (Chroicocephalus, Eyton.i 

 a. Tarsus longer than the middle t, e and claw. 



'•', L. atricilla. Bill and feet dark brownish red, the former .-• pped with 



brighter red; eyelids dull red; iris dark brown; hood dai slate; mantle 



p plumbeous- slab . Wing, about 13.00 inch 

 !», Tarsus shorter ti i olav . 



10. L. franklinii. Bill and feet carmini • : brown; hood pluml us 



mantle deep bluish plumbeous. Wing, about 11,25 ln< 



u. L. Philadelphia. Bill uniform deep black ; legs and feet One orange-recfin summer, 



flesh-color in wi dark brown; hood dark plumbeous; mantle delicate 



pearl-blue; Wing, about 10.25 inohes. 



12. L. m'nutus. Bill reddish dusky; legs and feel vermilion- or coral-red; hood deen 



black; mantle d ■ loate pearl-gray; primaries without any black markings. Wing, 



9.00 inohes, flab. Palaaarotic liegion ; accidental in Ma "sand 



Bei mudas. 



