STERNA HIEUNDO, COMMON TEEN. 681 



the very extremity of the feathers. The whole npper parts are grayish-blue, or rather 

 deep pe'arl-lihie, this color commencing insensibly on the back of the neck, deepening 

 on the dorsum, and extending, quite undiluted, almost to the extreme apices of the 

 tertials. The bluish color, however, ends quite abruptly and distinctly on the rump, 

 so that the superior caudal rectrices are pure white. The under parts are of a consid- 

 erably lighter shade of the color of the back. On the throat, toward the chin and 

 along the borders of the black pileum, it fades into nearly or quite pure white, as it 

 does also on the inferior caudal teotrices and the circumanal region. The inferior 

 surfaces of the wings and the axillary feathers are pure white. The shafts of all the 

 prim.iries are on their superior and inferior aspects white, but deepen into blackish 

 toward their apices. The outer web of the first primary is black, with scarcely any 

 hoariness. The first four or five primaries are grayish-black, with a very strong sil- 

 very hoariness ; their inner webs with a space of white along their inner margins. 

 This space on the first primary at the base occupies the whole web, becomes narrower 

 as it ascends, and ends, or becomes a mere line, about an inch from the apex of the 

 quill. On the other primaries it is of less extent, aad runs up along the centre of the 

 sliaft a little further than on the edge. On the innermost primaries, again, it is very 

 narrow, but forms an entire margin to the inner webs, running quite to their tips. 

 The inner primaries have scarcely any grayish-black, but are rather of the color of the 

 mantle. The secondaries are mostly purs white, but toward their ends have a space 

 grayish-blue of about equal extent on both webs. The tail is moderately elongated 

 and forked, contained about If times in the wing ; the folded wings reach one to two 

 inches beyond it. The central feathers are broad to their evenly rounded tips ; the 

 lateral ones successively narrower, more tapering and acute. The under tail-coverts 

 reach to the very tips of the central rectrices ; the upper fall a little short of them. The 

 rectrices are on their outer webs light pearl-gray (very like the back), their inner webs 

 nearly pure white. The external pair, however, are on most of their inner webs, 

 especially terminally, grayish-blue, while their outer webs are dark grayish-black.* 

 Legs and feet light coral-red. 



Dimensionii. — Length (average), 14.50 inches ; extent, about 31 ; wing, from the car- 

 pus, 10.50; tail, 6: depth of fork, 3.50 (average); bill, along culmen, 1.35; height .it 

 base, 0.33; from feathers on side of lower mandible to tip, 1.60; gonys, 0.80; gape, 

 2.10 ; tibiai bare, 0.50 ; tarsus, 0.80 to O.bS ; middle toe 0.75, its claw 0.30 ; outer 0.70, 

 its claw 0.16 ; inner 0.48, its cl.aw 0.14 ; hallux, with its claw, 0.28 ; whole foot, about 

 1.75. Mr. Allen has given some elaborate tables of measurements, showing the follow- 

 ing range of variation in size of adult birds from the same locality in the breeding 

 season. The extreme range, so far as I am .aware, is as follows : length, 13 to 16 ; ex- 

 tent, 29 to 32; wing, 9.75 to 11.75; tail, 5 to 7; tarsus, 0.66 to 0.87 ; bill, 1.25 to 1.50. 

 Females average a little less than the malts. Young fall under the above minima; 

 length down to 12, wing to 9, tail to 4, bill to 1.12, &c. 



Youny-of-ilie-year in Awjiist. — Upper mandible brown, becoming blackish on the cul- 

 men toward the tip, and somewhat fleth-colored basally along the tomia. Under 

 mandible light yellow, darkening into brown toward the tip. Mouth yellow ; feet 

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

 this gray is intermixed with large, roundish, illy-defined spots of bl.ackish ; on the 

 occiput and nape the black is the prevailing color, the extreme tips of the feathers 

 only being gray. On the sides of the head, as far as the eyes, the black is 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 dull, 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 macrura. The lesser wing-coverts along 

 the edge of the fore-arm form a continuous band of nearly pure brownish-black. The 

 lesser and median coverts are conspicuously tipped with yellowish-gray. The 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 tlie inner web, 

 dark plumbeous or ashy-gray. The primaries are colored almost exactly as iu the 

 adults. The rump is white, with a tinge of pearl-blue. The tail is but slightly forked, 

 the emargination being but little more than an inch. The inner webs of all the rec- 

 trices are nearly pure white, but the outer webs .are plumbeous-gray, increa ing in 

 intensity from within outward; so that the outer pair of rectrices, which are but 

 little tapering or elongated, have their outer webs grayish-black, deepest toward 

 their tips. The entire under plumage, including the under wing-coverts, is pure 

 white, with no trace of the plumbeous wash of the adults. 

 I hove never seen the adult winter plumage of this species, and am therefore unable 



* I have seen a single undoubted specimen of this species which had the outer web 

 of the exterior tail feathers, as well as the inner, almost pure white, both webs being 

 of the same color as in ^aratZisea. This, however, must be very rare. 



