810 
PROCEEDINGS OE THE ACADEMY OE 
light colored ; first, outer web wholly black, inner a rather lighter ashy than 
the black to within about three inches from the tip ; second, like the first, but 
the base of the outer web the color of the inner ; on the third, fourth and fifth 
the black gradually decreases in extent, till on the sixth it is merely a narrow, 
Subterminal bar ; the tips of all are white, smallest on the first, increasing 
successively on the others. Three lateral tail-feathers white, the others light 
pearl blue, deepest on the central. Bill deep carmine, crossed with black near 
the end, the extreme tip yellowish. Legs and feet red. Wing 11-25; bill above 
1-20 ; along gape 1*70 ; tarsus or middle toe and claw 1*50. 
Habitat . — Central America ; Panama, (Suckley) ; Louisiana, (Wurdemann.) 
Closely allied to Ch. FranJclinii and much resembling it. Easily to be distin- 
guished by the characters of the primaries, as will be seen by comparing the 
descriptions given. 
20. Chroicocephalus Franklinii Bruch ex Richardson. 
Larus Franklinii, Richard. 1831. Chroicocephalus Franklinii , Bruch, 1855. 
Sp. Char. — Bill comparatively longer and slenderer than in cucullatus, the 
tip more attenuated and decurved. The angle well- defined and acute ; but the 
depression of the tip makes it less prominent, gonys from angle to tip concave. 
Adult : Mouth and bill bright carmine, the latter crossed with black near the 
end. Feet dusky carmine. Edges of eyelids orange. A conspicuous white 
patch above and below the eye, and behind it. Hood deep plumbeous black, 
encircling the upper part of the neck as well as the head, and extending much 
further on the throat than nape. Mantle as in cucullatus. Primaries : Shaft 
of first white, of others white except along the black portions of the feathers ; 
first, its outer web black to within an inch of the end, its inner pearly white, 
crossed by a black bar near the end, the tip white for almost an inch ; next 
five crossed by a black bar near the end, two inches wide near the end, gradu- 
ally narrowing to a black spot on the sixth ; bases of all the color of the back 
fading into white along the outer edge of the inner vane and adjoining black 
portions ; tips of all white. Tail feathers as in cucullatus. Length 14 inches, 
extent 35, wing 11-25. Bill above 1-25, gape 1-75, tarsus or middle toe and 
claw 1-60. 
Habitat. — Interior of Arctic America; Nebraska ; Texas ; Mexico. 
21. CHROicocEPHALd^PHiLADELPHiA Lawrence ex Ord. 
Sterna Philadelphia, Ord, 1815. Chroicocephalus Philada., Lawrence, 1858. 
Larus capistratus, Bonap., 1828. L. Bonapartei , Richardson, 1831. 
Chroicocephalus Bonapartei , Bruch, 1855. 
Sp. Char. — Bill shorter than the head or tarsus, much compressed, slender, 
and sternine. Both mandibles with a slight but distinct notch near the tip. 
Nostrils linear, exceedingly narrow. Adult : Bill black ; mouth carmine ; legs 
and feet chrome, tinged with' vermillion. T Webs bright coral red. Hood 
plumbeous slate, not so deep as in Franklinii , enveloping the head and upper 
part of the neck, reaching further before than behind. White patches on eye- 
lids narrow. Mantle pearl blue, much lighter than in Franklinii or cucullatus , 
not so light as in minutus. Ends of the tertials and scapulars scarcely lighter 
than the back. Primaries : Shafts of the first five or six white except at their 
extreme tips, the others dark colored ; first, outer web and extreme tip black, 
rest white ; second, white, its tips black for a greater distance than the first, 
and on one or both webs, for a greater or less distance (sometimes half way 
down the feather) narrowly bordered with black; third, fourth, fifth, sixth, 
black at the ends for about the same distance on each, the black bordering the 
inner web much further than the outer ; the inner webs of the third and fourth, 
and both webs of the fifth and sixth, of a rather lighter shade of the coloi^f 
the back. Other primaries like the back, the seventh and eighth with a touch- 
of black on one or both webs. Length 14 inches, extent 32, ’wing 10-25. Bill 
above 1-20, gape 1-75, tarsus or middle toe and claw 1-40. 
Habitat. — Entire continent of North America. 
