LARIDA —LARINZZ: GULLS. 741 
Smaller: length about 24.00 inches; wing 17.00 or less; bill about 2.00; tarsus 2.25 /ewcopterus 769 
Mantle light blue; primaries the same, with definite white tips . . . . .. . glaucescens T70 
Mantle very pale blue, as in /ewcopterus ; primaries with slate-gray reeicentes . . « kumlient Tia 
B. Very large: mantle slaty-blackish; primaries crossed with black; size of thefirst . . marinus 171 
C. Large: mantle some shade of blue, darker than in 4, lighter than in £; primaries crossed with black. 
Mantle grayish-blue ; bill moderately robust ; feet fesh-colored aan ah or smithsonianus 772, 773 
Mantle slaty-blue; bill very robust; feet flesh-colored . .. . . . « occidentalis T74 
Mantle dark grayish-blue; bill moderately robust; feet yellow; ol oriined . cachinnans 775 
Mantle dark slate; bill moderately robust; feet flesh-colored. . .. . - . . afinis Ti6 
D. Medium and small: primaries crossed with black; feet dark-greenish; wets Rollo 
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 TTT 
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 brachyrhynchus 779, 780 
Il. Tail and under parts darkin adult. Head white; bill and feet reddish. (Blasipus.) 
Back slatyalead Color, s. eeeitsi | sche) eerie adie on Nits Vetin tO stp Ge) are eis heermanni 781 
L. glau'eus. (Gr. yAavxds, 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 g 9: Bill large 
and strong, very wide, but not so deep at angle nor so convex at end as in marimus, 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, ete. Northern and Arctic seas, cireumpolar ; 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 Z. marinus in 
these respects. 
L. leucop/terus. (Gr. Aevkds, leucos, white; mrepdv, pteron, wing.) WHITE-WINGED 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 ZL. 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. 
L. 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 Ist 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 
