S. SUPERCILIAEIS VAE. ANTILLAKUM, LEAST TEEN. 693 



DiAG. S. mimitai similis ejusdemque statural ; sed uropygio canddque cum pallio concolori- 



ius, rostro hreviore, graciliore, viitd frontali migustiore; rostroflavo, apice nigra, pedibu8 



flams. 



i7a6.— Temperate North America, especially along the Atlantic coast of the United 

 States, but also on the larger inland waters. Up the Pacific coast to California (^Xantus, 

 Coues). South into the Antilles and Middle America generally. Apparently winters 

 beyond the United States. (The typical siqyerciliaris from South America; Brazil, Para- 

 guay, &c.) 



Lieutenant Warren's Expedition.— 900b, FHtteHiTeT; 9007, Loup Fork ; 8999, Yellow- 

 stone River. 



Adult, hreeding plumage. — Bill about as long as the head, slightly exceeding the tarsus 

 and middle toe together without the claw ; compressed; only moderately robust; the 

 tip very acute, but not much attunuated nor decurved. Culmen straight to the nos- 

 trils, slightly but equally decurved for the I'est of its extent; commissure curved 

 throughout ; rami concave in outline, short ; gouys straight, much longer than the 

 ramus. Nasal groove tolerably wide, but very short, aud not deep. Tomia slightly 

 inflected. Wings of moderate length ; first primarj' but very slightly longer than the 

 second; the rest successively more and more rapidly graduated. Tertials and inner 

 secondaries very short, reaching in the folded wing only half way to its tip. Tail 

 rather short, and only moderately forked ; the central rectrices broad, with broadly 

 rounded tips ; the external pair narrowing rapidly to a very acute tip. Tibiae bare but 

 a very short distance. Feet small, short, slender ; t.arsus equal to middle toe and half 

 its claw ; of ordinary characters as legiirds scutellation and reticulation. Outer toe 

 almost or quite as long as the middle, with its claw very much shorter and weaker; 

 iuner toe short, its claw just reaching to the base of the middle claw. Unguis of hal- 

 lux extremely minute. Webs moderately broad; the outer only slightly, the inner 

 very considerably, incised. 



Bill yellow, its tip for usually an eighth to a fourth of an inch black, but sometimes 

 altogether yellow. The junctiou of this black with the yellow is quite straight and 

 perpendicular, as it does not run off on the gonys, nor culmen, nor tomia. Pileum 

 glossy greenish-black. On the forehead a naiTvw lunula of white, the posterior border 

 of which is very concave, the narrow cornua of which extend over the eyes just to 

 their posterior borders. This crescent extends quite to the bill, but is separated from 

 the white of the cheeks by a narrow line of black, which runs forward as a prolonga- 

 tion of the pileum, through the eyes, to the extreme tip of the feathers on the side of 

 the bill. The entire upper parts of the bird, including its rump, nape, upper tail- 

 coverts, and the rectrices themselves, are pearl-blue, with a considerable tinge of 

 plumbeous. This color extends undiluted quite to the black pileum, on the sides of 

 the neck and head fading insensibly into the pure white of the under parts. The rec- 

 trices are about the color of the back, only they grow lighter toward their bases, and 

 their under surfaces, together with the outer web of the first, are nearly white. The 

 color of the hack extends undiluted to the extreme apices of the secondaries and ter- 

 tials, but the inner webs of these feathers are bosally nearly white. The shafts of the 

 first two primaries are white iuferiorly, black superiorly ; the webs themselves black, 

 the inner with a considerable space white ; this white space separated from the black 

 by a tolerably distinct line of definition, not extending to the tip of the feather. The 

 other primaries are a considerably darker shade of the color of the back, their inner 

 webs fading into whitish along their borders, which thus become conspicuously mar- 

 gined with white quite to their tips. Whole under parts, including the inferior alar 

 tectrices, pure white, without the least wash of plumbeous or tinge of rosy. Feet 

 orange yellow, the claws black. 



Toward the middle or latter part of July, the bird above described begins to change, 

 and, until it has fully completed its autumn moult, its plumage is as follows : 



Adults duriiig the August moult. — Bill mostly black, but a greater or less degree of 

 yellow remaining. The black pileum has already become variegated with white, the 

 front beiug mostly of that color. The upper parts are as in summer, but there are 

 indications of the dusky band that is to appear along the fore-arm. Tail scarcely at 

 all forked, from wearing away of the central rectrices. A larger number of the pri- 

 maries are blackish, without a silvery tinge, and this grayish-black extends along the 

 radial edge of the metacarpus to the carpal joint on the feathers of the ala spuria. 



At the finishing of the moult we have the — 



Adult, tcinter plumage. — Bill black ; legs and feet dull yellowish. Forehead aud lores 

 pure white ; vertex white, with more or less numerous, narrow, longitudinal lines of 

 black; occiput and nape wholly brownish-black, sending forward on each side over 

 the aurioulars, to just in front of the eye, a band of the same. The upper parts are as 

 in the adults in summer, but rather darker, and the mantle does not, as in summer, 

 extend quite up to the nape, but leaves a portion of the neck behind white, as are also 

 the whole under parts. There is a continuous band of grayish-black along the fore- 

 arm ; the bend of the wing from the primaries to the carpal joint is also of this color. 



