BIRDS OF NORTH AND MIDDLE AMERICA. 645. 
Clhroicocephalus] cucullatus SucKLEY, in Cooper and Suckley, Rep. Pacific R. R- 
Surv., xii, pt. ii, 1860, 277, ia text (Panama), 
[Gavia] cucullata Bonaparte, Compt. Rend., xlii, 1856, 771. 
[Chroicocephalus] kittlitzii Brucu, Journ. fiir Orm., 1853, 104 (s. Chili; based on 
a drawing). 
[Gavia] kittlitzii Bonaparte, Compt. Rend., xlii, 1856, 771. 
[Chroicocephalus] schimperi Brucu, Journ. fiir Orn., 1853, 104 (‘‘New Zealand’’). 
[?] [Chrotcocephalus] serranus (not Larus serranus Tschudi) Brucu, Journ. fir 
Orn., 1853, 106 (Peru). 
Larus cinereo-caudatus Purrert and Lanppeck, Wiegmann’s Archiv fiir Naturg., 
1861, i, 293. 
CHROICOCEPHALUS PHILADELPHIA (Ord). 
BONAPARTE'S GULL. 
Adults in summer (sexes alike)—Head and upper part of neck 
dark gray (between dark and dusky purplish gray); an elongated 
white spot on each eyelid; lower neck (all round), entire under parts, 
including axillars and under wing-coverts, lateral and lower portions 
‘of rump, upper tail-coverts, tail, edge of wing, alula, primary coverts 
and greater portion of distal primaries immaculate white, the neck 
‘and under parts often suffused with delicate cosine pink (especially 
in life and more recently killed specimens); back, scapulars, greater 
part of wings (except distal primaries) and upper and median por-- 
tions of rump, uniform delicate pale neutral gray; outer web of outer- 
most primary and terminal portion of first, second and third (count- 
ing from outside) black; fourth primary similar to third but inner 
web pale neutral gray; fifth and sixth primaries pale neutral gray 
with a large subterminal space of black and tipped with white (the 
third and fourth also with a small apical spot of white); remaining 
(proximal) primaries pale neutral gray, without white tips but with 
a subterminal spot (usually, or mostly, on inner web only) of black; 
bill black; interior of mouth, together with legs and feet, clear, rich 
orange-red or orange-vermilion; iris dark brown; naked orbital ring 
black. 
Adults in winter.—Similar to summer adults, but head and whole 
neck white, the occiput tinged with gray and the auricular region 
with a spot of dusky grayish; legs and feet paler red or flesh color. 
Young.—Lateral and under portions of head and neck, entire 
under parts, upper tail-coverts, and basal three-fourths (approxi- 
mately) of tail immaculate white; a dusky spot on auricular region; 
crown, occiput, and upper back grayish brown; scapulars and pos- 
terior interscapulars (lower back) grayish brown tipped with pale 
buff; central area of lesser wing-covert region dusky grayish brown; 
rest of wing-coverts, edges of secondaries, greater portion of proximal 
primaries, and upper and median portions of rump light neutral 
gray; distal portion of tail (forming a well-defined broad band) black 
