LABID2E — LABIN^: GULLS. 141 



Smaller: length about 24,00 inches; wing 17.00 or less ; bill about 2.00; taTBVi%2.26 leucopterus 769 



Mantle light blue ; primaries the same, with detinite white tips giaucescens 110 



Mantle very pale blue, as in ^eucoju^eras; primaries with slate-gray markings . . . . kumlleni 110a 



B. Very large: mantle slaty-blackish; primaries crossed with black; size of the tirst . . marinus 111 



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



": Mantle grayish-blue ; bill moderately robust ; feet llesh-colored argaiiatus or smithsonlamis 772, 773 



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



Mantle dark grayish-blue; bill moderately robust; feet yellow; eye-ring orange . cachinnans 775 

 Mantle dark slate; bill moderately robust; feet flesh-colored affinls 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; tirst pruuary usually with a sub-apical white spot ; length about IS. 00-22. 00 



delawartns is 118 

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

 band, if any; first primary usually with the end broadly white; length about 20.00-22.00 



ccdlfonilciLS 111 

 Tarsus little if any longer tban 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 reddissh. {Ulasijjus.) 



Back slaty-lead color heennannl 781 



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

 BuEGOMASTEXi. Viii-y large : length about 30.00 ; extent 60.00; wing up to IS. 50; bill 2.75- 

 3.00 (chord of culinen), along gape 3.75, its depth opposite nostrils 0,80, at angle 0.85 ; tarsus 

 3.00-3.25 ; middle toe and claw 3.75. No black anywhere at any age. Adult ^ ? : 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; chronie yellow, the tip diaphanous yellow, a vermilion spot at 

 the augle. Logs 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, whuUy white. In winter : 

 Head and hiud neck lightly touched with pale brownish-gray. An innnature 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; und'er 

 parts a nearly uniform pale shade of brownish; quills and taU imperfectly barred Avith the same 

 Smaller : wing 17.50 ; bill 2.40 ; tarsus 2.40, etc. Northern and Arctic seas, circumpolar • ^. 

 m wmter 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 X. marinus in 

 tliese respects. 



769. L. leucop'terus, (Gr. Xet-^dr, leucos, white; nr,p6., pteron, wing.) White-wixgfd Guli 

 Precisely like the last, but s.naUer. Length 2i.OO, rather less than more ; wing 10 00-17 00 ■ 

 bill along culuien 1.75-2.00, along gape about 2.7.5 ; depth at angle 0.65 ; tarsus 2 00-2 25* 

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

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

 istic of N. Am. than of Europe. 



770. L. glauces'eens. (Lat. f,laucescens, growing bluish.) GLAUCOUS-wiNaBD Gull. Like a 

 herrmg gnll with the black of the primaries washed out; primaries of the color of the mantle 

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

 white sub-terminal spot. Bill long and rather weak, the upper mandible acute and proiecting 

 considerably beyond tip of the under, the convexity near the end comparatively slight an^le 

 pretty well defined, tie 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 3^5 ■ 

 gape 3.2o ; 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 inst above' 

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

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



