984 SYSTEMATIC SYNOPSIS. —LONGIPENNES. 



family, being those most typical of it. White, with a darker mantle, without a hood or col- 

 lar ; head and neck in winter streaked with dusky (Larus proper) ; or dark, with white head 

 and red bill (Blasipus). 



Analysis of Species. 



I. Tail and under parts white in adult ; bill and feet not reddish. {Larus.) 



A. Large and robust ; mantle whitish or pale pearly ; no black on primaries at any age. 



Mantle very pale pearly ; primaries the same, fading insensibly into white far from tips. 



Larger : length about 30.00 inches ; wing 18.00 or more ; bill and tarsus, each, about 3.00. Arctic, 



Pacific, Atlantic glaucus (and barrovianus f) 



Smaller : length about 24.00 inches ; wing 17.00 or less ; bill about 2.00 ; tarsus 2.25. Arctic and 



Atlantic leucoptervs 



Mantle light blue ; primaries the same, with definite white tips. Pacific glaucescens 



Mantle very pale blue, as in leucopterus ; primaries with slate-gray markings. 



Smaller : wing 16.00-17.00. Atlantic kumlieni 



Larger : wing over 17.00. Pacific nelsoni 



B. Very large : mantle slaty-blackish ; primaries crossed with black. 



Largest : size of (?/«!/«« ; length 30.00; wing 18.00-19.00. Atlantic marinus 



Not 80 large : length about 26.00 ; wing 17.00-18.00. Pacific . ■. schistisagus 



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. N. Am. at large 



{argentatus or) smithsonianus 



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



Mantle dark grayish-blue ; bill moderately robust ; feet flesh-color. Pacific vegm 



Mantle dark slate ; bill moderately robust : feet yellow. Greenland only affinis 



D. Medium and small : primaries crossed with black ; feet greenish or yellowish ; webs yellow. 



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

 band ; first primary usually with a sub-apical white spot ; length about 18.00-20.00. N. Am. at large 



delawarensis 



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

 first primary usually with end broadly white ; length about 20.00-22.00. Western N. Am. californicus 



Tarsus little or not longer than middle toe and claw ; bill slender, greenish, without black band or red spot; 

 size very small ; length 16.00-18.00. Chiefly Arctic and Pacific (Labrador?) {canus or) brachyrhynchus 



II. Tail and under parts dark in adult. Head white ; bill and feet reddish. {Blasipus. ) 



Back slaty-lead color. Pacific heermanni 



(^Subgenus Larus.) 



L. glau'cus. (Gr. ykav<6s, glauJcos, Lat. glaucus. bluish.) GLAUCOUS GuLL. ICE GuLL. 

 Burgomaster. Very large : Length about 30.00 ; extent 60.00; wing up to 18.50 ; tail up 

 to 8.50; 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 in summer : Bill large and strong, very wide, but not so deep at angle nor so con- 

 vex at end as in marinus, about as long as middle toe and claw ; chrome yellow, the tip di- 

 aphanous yellow, a vermilion spot at 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. A supposed immature stage (the so-called L. hutchinsi) : 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 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. Downy young: Pale gray, still paler below, the upper parts 

 marked with dusky gray spots. Eggs 2 or 3, 3.15 X 2.15. Northern and Arctic seas, circum- 

 polar; S. in winter in North America to the Middle States and San Francisco Bay, coastwise, 

 and in the interior to the Great Lakes. This is one of the very largest and most powerful birds 

 of the whole family, fully equalling marinus in these respects. 



L. barrovia'nvis ? (Lat. relating to Sir John Barroiv, for whom Point Barrow on the N. 

 coast of Alaska was named.) Point Barrow Glaucous Gull. Identical with the last in 



