LABIDJE — LARIN^ : GULLS. 
741 
Smaller : length about 24.00 inches ; wing 17.00 or less ; bill about 2.00 ; tarsus 2.25 leucopterus 769 
Mantle light blue ; primaries the same, witli definite white tips glaucescens 770 
Mantle very pale blue, as in ^e«cojj^('?-ws,- primaries with slate-gray markings . . , . kuviiieni 770a 
^. Very large : mantle slaty-blackish ; primaries crossed with black ; 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 occidtntalis 774 
Mantle dark grayish-blue ; bill moderately robust ; feet yellow ; eye-ring orange . cachinnans 775 
Mantle dark slate ; bill moderately robust; feet flesh-colored affinis 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 
delawarensis 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 
californicus 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 brachyrhijnchus 779, 780 
II. Tail and under parts dark in adult. Head white; bill and feet reddish. {Blasipus.) 
Back slaty-lead color hecrmanni 781 
768. Li. glau'cus. (Gr. yXavKos, glaukos, Lat. glaucus, bluish.) GLAUCOUS Gull. Ice Gull. 
Burgomaster. Very large : length about 30.00 ; extent 60.00; wing up to 18.50; bill 2.75- 
3.00 (chord of culmen), along gape 3.75, its depth opposite nostrils 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 yellow, 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, wholly white. In winter : 
Head and hind neck lightly touched with pale brownish-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 ; quills and tail imperfectly barred with the same. 
Smaller: wing 17-50; bill 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_ L. leucop'terus. (Gr. XevKos, leucos, white ; nrepov, pteron, wing.) White-w^inged Gull. 
Precisely like the last, but smaller. Length 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. glaucus 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. 
77Q_ Li. glauces'cens. (Lat. glaucescens, growing bluish.) Glaucous- winged Gull. Like a 
herring gull with the black of the primaries washed 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. Bill long and rather weak, 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 straight. 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 in 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 
