LARIDJE — LABIN^ . GULLS. ' 741 



Smaller: length about 24.00 inches ; wing 17.00 or less ; bill about 2.00; tarsus 2.25 /ej/cop/crns 76;) 



Mantle light blue; primaries the same, with definite white tii)B glaucescens 770 



Mautle very pale blue, as in /('KtOi^/erMs; primaries with slate-gray marliings . . . . kumtieni 770« 

 .B. Very large : mantle slaty-blackish ; primaries crossed with blaclc ; size of the first . . marinus 771 

 C Large : mantle some shade of blue, darker than in A, lighter than in B; primaries crossed with black. 



Mantle grayish-blue ; bill moderately robust ; feet flesh-colored argentatus or smithsonianus 772, 773 



Mantle slaty-blue; bill very robust; feet flesh-colored occidenlalis 774 



Mantle dark grayish-blue ; bill moderately robust ; feet yellow ; eye-ring orange . cachinnans 770 



Mantle dark slate ; bill moderately robust; feet flesh-colored ajfinis 776 



D. Medium and small : primaries crossed with black ; feet dark-greenish ; webs yellow. 



Tarsus obviously longer than the middle toe and claw ; bill of adult greenish-yellow, encircled 

 with a black band; first primary usually with a sub-apical white spot ; length about 18.00-22.00 



delaicarensis 778 

 Tarsus little if any longer than middle toe and claw ; bill with a red spot, but an imperfect black 

 band, if any; first primary usually with the end broadly white; length about 20,00-22.00 



cali/orntciis 777 

 Tarsus little if any longer than the middle toe and claw ; bill slender, greenish, without a black 

 band or red spot ; size very small ; length 16.00 or 18.00 .... canus or brachyrhyiickus 779, 780 

 n. Tail and under parts dark in adult. Head white ; bill and feet reddish. (Jilasipus.) 



Back slaty-lead color heennanni 781 



768. ^- glau'cus. (Gr. yXavKos, glaiikos, Lat. glaums, bluish.) Glaucous Gull. Ice Gull. 

 Burgomaster. Very large : leugth about 30.00 ; extent 60.00; M'ing up to 18.50; bill 2.75- 

 3.00 (chord of culuien), along gape 3.75, its depth opposite nostrUs 0.80, at angle 0.85 ; tarsus 

 3.00-3.25 ; middle toe and claw 2.75. No black anywhere at any age. Adult $ 9 : Bill large 

 and strong, very wide, but not so deep at angle nor so convex at end as in marinus, about as 

 long as middle toe and claw ; chrome yellow, the tip diaphanous yeUow, a vermilion spot at 

 the angle. Legs and feet pale flesh-color or yellowish. Iris yellow. Primaries entirely white, 

 or palest possible pearly-blue, fading insensibly into white at some distance from their tips, their 

 shafts straw-yellow. Mantle very pale pearl-blue. Otherwise, whoUy white. In winter : 

 Head and liind neck lightly touched with pale bro^-uish-gray. An immature stage : Entirely 

 white ; bill flesh-colored, black-tipped. Young : Bill flesh-colored, black-tipped ; plumage 

 impure white, mottled with pale reddish-brown, sometimes quite dusky on the back ; under 

 parts a nearly uniform pale shade of brownish ; quOls and tail imperfectly barred with the same. 

 Smaller: wing 17.50; biU 2.40 ; tarsus 2.40, etc. Northern and Arctic seas, circumpolar ; S. 

 in winter in N. Am. to the Middle States, coastwise ; breeds only in the high north. This is one 

 of the very largest and most powerful birds of the whole family, fully equalling L. marinus in 

 these respects. 



769. I^- leucop'terus. (Gr. XeuKoy, leucos, white; irrepov, ijteron, wing.) White- winged Gull. 

 Precisely like the last, but smaller. Leugth 24.00, rather less than more ; wing 16.00-17.00 ; 

 bill along culmen 1.75-2.00, along gape about 2.75 ; depth at angle 0.65 ; tarsus 2.00-2.25, 

 not longer than middle toe and claw. This counterpart of L. glaucns inhabits the same north- 

 erly regions, coming south to the same degree in winter. It appears to be much less character- 

 istic of N. Am. than of Europe. 



TIO. ^- glauces'cens. (Lat. glaucescens, growing bluish.) Glaucous-winged Gull. Like a 

 herring gull with the black of the primaries waslied out ; primaries of the color of the mantle 

 to the very tips, which are occupied by definite small white spots ; the 1st also with a large 

 white sub-terminal spot. BUI long and rather Aveak, the upper mandible acute and projecting 

 considerably beyond tip of the under, the convexity near the end comparatively slight ; angle 

 pretty well defined, the outline between it and the tip about straiglit. Tarsus rather longer 

 than middle toe and claw. Length about 27-00; wing 16.75; bill along culmen 2.25; 

 gape 3.25 ; depth at angle 0.70 ; tarsus 2.60 ; middle toe and claw 2.50. Adult iu summer : 

 Bill light yellow, an orange spot at angle of lower mandible, and a dusky one just above. 

 Mandible pearl-blue, much the same shade as in argentatus. Primaries scarcely darker than 

 the back, all with well-defined, rounded apical spots of white. First, the base not appreciably 



