BIRDS OF NORTH AND MIDDLE AMERICA. 669 
RHODOSTETHIA ROSEA (Macgillivray). 
ROSS'S GULL. 
Adults in summer (sexes alike).—Head, neck, entire under parts, 
including axillars, lower rump, upper tail-coverts and tail immacu- 
late white, the neck and under parts more or less strongly (often 
deeply) suffused with pure eosine pink; a narrow collar of black 
round upper part of neck, widest in front, formed by black tips to 
the feathers; back, scapulars, upper rump, and wings (including their 
under surface), pallid neutral gray (very slightly darker on wings), 
the secondaries and proximal primaries tipped with white or pink, 
the outer web of outermost primary mostly black or blackish; bill 
black; rictus and naked orbital ring deep orange to vermilion red 
(in life); iris dark brown; legs and feet orange-red, vermilion, or 
coral red (in life). 
Adults in winter.—Similar to summer adults but without any black 
collar, and pileum tinged with pale gray. 
Immature (second summer).—Similar to summer adults, but lesser 
and middle wing-coverts dusky or blackish superficially (only the 
concealed portion being pale gray); proximal secondaries, alula, and 
adjacent small feathers, together with three outer primaries, dusky 
or blackish, the inner webs of the last, however, with the marginal 
half pale gray; remaining primaries pale gray passing into white on 
the innermost ones, all of them broadly tipped with black; tail white, 
but third, fourth, and fifth pairs of rectrices (counting from outside) 
broadly tipped with black, this about 19 mm. wide on the fifth Mext 
to middle) pair. 
Young (first autumn).—General color of upper parts pallid neutral 
gray superficially (the feathers white beneath surface), but this 
broken by heavy cloudings of dark sooty, many of the feathers 
being broadly tipped with this color, the dusky prevailing on upper 
rump, where the feathers are narrowly tipped with dull buffy; 
lower rump, upper tail-coverts and greater part of tail immaculate 
white, the six middle rectrices tipped with sooty blackish, this about 
20-22 mm. wide on middle pair but reduced on third pair (from 
middle) to a slight mottling at extreme tip; lesser and middle wing- 
coverts, tertials, and most of scapulars dark’ sooty or sooty blackish, 
margined terminally with pale grayish buffy; greater wing-coverts 
immaculate pallid gray fading into white terminally; secondaries 
and two innermost primaries white; next two primaries with white 
inner webs and shafts, the outer webs pallid gray, the third (from 
inside) with inner web narrowly margined with black terminally, 
the fourth with an elongated spot of black on distal portion of each 
4 Tn some specimens this pink suffusion pervades practically the entire plumage, 
even the pale gray of the ‘‘mantle” being more or less tinged by it. 
