LABILE — STEBNINJE ; TEENS. 



763 



798. 



14.50 inches ; extent about 31.00 ; wing from the carpus 10.50 ; tail 6.00 ; depth of fork 3.50 

 (average) ; bill along culmen 1.35 ; height at base 0.33 ; from feathers on side of lower man- 

 dible to tip 1.60 ; gonys 0.80; gape 2.10; tibias bare 0.50; tarsus 0.80 to 0.85 ; middle toe 

 0.75, its daw 0.30 ; outer 0.70, its claw 0.18 ; inner 0.48, its claw 0.14 ; hallux with its claw 

 0.28 ; whole foot about 1.75. Extreme range : length 13.00 to 16.00 ; extent 39.00 to 32.00 ; 

 wing 9.75 to 11.75 ; tail 5.00 to 7.00 ; tarsus 0.66 to 0.87 ; bill 1.25 to 1.50. Females average 

 a little less than the males. Young fall under the above minima ; length down to 12.00, wing 

 to 9.00, taU to 4.00, bill to 1.12, etc. Young-of-the-year in August : Upper mandible brown, 

 becoming blackish on the culmen toward the tip, and somewhat flesh-colored basaUy along 

 the tomia. Under mandible light yeUow, darkening into brown toward tip. Mouth yellow ; 

 feet dull yellow, with scarcely a tinge of reddish. Forehead grayish-white ; on the vertex this 

 gray intermixed with large, roundish, illy-defined spots of blackish ; on occiput and nape black 

 is the prevailing color, the extreme tips of the feathers only being gray; on sides of head, as 

 far as eyes, the black also nearly pure. The ground-color of the upper parts is a rather lighter 

 shade of the pearl-blue of the adults, but every feather is tipped with duU light gray, and has 

 a subterminal spot (generally a crescent or semicircle) of light brown. These spots and tips 

 are quite conspicuous, and give perhaps the predominating color to the upper parts ; but they 

 are not so distinctly defined, nor so dark, as in macnwa. Lesser wing-coverts along the edge 

 of the fore-arm form a continuous band of nearly pure brownish-black. Lesser and median 

 coverts are conspicuously tipped with yellowish-gray ; greater secondaries, however, fade into 

 nearly pure white at their tips. The secondaries are white, with the outer web, except at tip, 

 and the median portion of the inner web, dark plumbeous or 

 ashy-gray. Primaries colored almost exactly as in the adults. 

 Rump white, with a tinge of pearl-blue. Tail sUghtly forked, 

 the emargination being but little more than an inch ; inner 

 webs of aU the rectrices nearly pure white, but the outer webs 

 are plumbeous-gray, increasing in intensity from witMn out- 

 ward ; so that the outer pair of rectrices, which are but little 

 tapering or elongated, have their outer webs grayish-black, 

 deepest toward their tips. Entire under plumage, including 

 the under wing-coverts, pure white, with no ta'ace of the 

 plumbeous wash of the adults. The winter range and changes 

 of plumage of this familiar species are not well known ; it 

 does not appear to lose the black cap, which nevertheless is 

 imperfect at that season. North America at large, Europe, 

 etc. Breeds and winters variously in its N. A. range. 

 Eggs 3, 1.65 X 1.25, not distinguishable from those of allied 

 species. 



S. for'steri. (To J. E. Forster. Figs. 50, 516.) Forstee's 

 Tekn. Similar to the last ; larger ; bill longer, stouter ; 

 wings shorter, tail longer; feet longer. Length about 15.00; 

 extent 30.00 ; wing 9.50-10.50 ; tail 5.00-8.00, forked 2.50- 

 5.00; bin along culmen 1.50-1.75, averaging 1.60, its depth at base 0.40 ; tarsus 0.90-1.00 ; 

 middle toe and claw 1.00-1.10; whole foot averaging 2.00. Adult, spring plumage: BUI 

 orange-yellow, black for nearly its terminal half, the extreme points of both mandibles yellow- 

 ish ; robust, deep at base ; culmen dechnato-convex, eminence at symphysis well developed ; 

 length from -jlj to -^ of an inch longer than that of S. Mrwndo. Black pileum not extending 

 so far down on sides of head as in Mrwnda, barely embracing eye (the lower lid of which is 

 white), and leaving a wider white space between the eye and edge of superior maxUla than 

 in hirimdo. The color of the back hardly differs from that species ; perhaps a shade lighter. 



Fig. 616. — Tail of Forster's Tern, 

 about I nat, size. (From Elliot.) 



