750 . SYSTEMATIC SYNOPSIS. — LONGIPENNES— GAVI^: 



gulls. Tail square, or uearly so. There are no marked peculiarities of form of this genus, 

 the pattern of coloration being mainly its basis. The numerous species average much under 

 those of Larus in size (though one at least is among the largest of Larince) : they approximate 

 toward Xema and Bhodostethia in some respects, but the tail is neither forked nor cuneate. 



Aiialysis of Species. 



Tarsus longer than middle toe and claw. 



Bill reddish, feet the same. Length 16.00 or more atricilla 786 



Tarsus not longer than middle toe and claw. 



Bill reddish, feet the same. Length about 14.00 inches franklini 787 



Bill black, feet red or yellow. Length about 14.00 inches Philadelphia 788 



786. C. atricil'la. (Lat. atricilla, black-tail: only applicable to the young. Fig. 510.) Laughing 

 Gull. Black-headed Gull. Bill h)uger than middle toe and claw, shorter than tarsus or 

 head, moderately compressed, rather stout for this genus. Cuhrien and commissure both decurved 

 at the end, the latter somewhat sinuate at the base. Gonys considerably concave in front 

 of the angle, somewhat so between the angle and tip ; although the angle is well defined, 

 the tip of the bill is so decurved that a chord from tip to base does not touch it. Middle toe 

 barely three-fourths the tarsus. Adult in summer : BOl and edges of eyelids deep carmine ; 



legs and feet dusky-red j iris blackish. Hood 

 deep plumbeous grayish -black, extending further 

 on the throat than on the nape. Eyelids white 



(^ 



*^ posteriorly. Neck all round, rump, tail, broad 

 tips of secondaries and tertials, and whole under 

 parts, white, the latter with a rosy tinge (like tl*' 

 tint of peach -blossoms). Mantle grayish -pluii\- 

 beous. Ojuter six primaries black, their extreme 

 tips white ; their bases for a very short distance 

 Fig. 510.— Bill of Laughing Gull, uat. size. (Ad on the first, and only on the inner web, and for a 

 nat. del. E. C.) successively increasing distance on both webs of 



the others, of the color of the back. Adult in winter : Under parts simply white, not rosy ; 

 hood lost, the head being white, mixed with blackish. BiU and feet more dull in color. Imma- 

 ture : Bill and feet brownish-black, tinged with red. Plumbeous of the upper parts more or 

 less mixed with irregular patches of light grayish-brown. Primaries wholly brownish-black, 

 fading at the tip. Secondaries brownish-black on the outer web. Tail-feathers more or 

 less tinged with plumbeous, and with a broad terminal band of brownish-black, the extreme 

 tips of the feathers white. Upper taU-coverts white. Young-of-the-year : Entire upper 

 parts, and neck aU round, light brownish-gray ; the feathers tipped with grayish or rufous- 

 white, broadly on the scapulars and tertials, the blue of the adults appearing on the wing- 

 coverts. Eyelids whitish ; a dusky space about the eye. Forehead, throat, and under parts, 

 dull whitish, more or less clouded, with gray, especially on the breast, where this is the 

 prevailing color. Wings and tail as before. Length about 16.50 ; extent 41.00; wing 13.00; 

 tail 5.00; bill 1.75, along gape 2.25, its height at nostril 0.45 ; tarsus 2.00; middle toe and 

 claw 1.50. Tropical Am. and temperate N. Am. ; in the U. S. north coastwise in summer to 

 Maine, in the interior to Ohio or beyond ; on the Pacific side to California ; Central America, 

 both coasts, and various W. I. islands ; S. Am. to the Lower Amazon ; casual in Europe. 

 By thousands along the Atlantic coast during the migrations, breeding in colonies anywhere 

 along, wintering in the South. Nest on the ground, of eel-grass, seaweeds, and other vege- 

 table material; eggs mostly 3, sometimes 2; 2.10X1.55; ground color some oUve shade, 

 ranging from dull grayish to dark greenish, thickly marked all over with spots and irregular 

 splashes of brown, blackish, duU reddish and pale purpUsh ; sometimes the markiiigs chiefly 

 wreathed about the large end. 



