STERNA HIRUNDO, COMMON TERN. 681 



the very estreuiity of the feathers. The whole upper parts are grayish-blue, or rather 

 deep pearl-blue, this color coramenciug insensibly ou 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 ou the rump, 

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

 erably lighter shade ol' the color of the back. Ou 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 tectrices and the circumanal region. The inferior 

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

 primaries are ou their superior and inferior aspects white, but deepen into blackish 

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

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

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

 This space ou 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, and runs up along the centre of tho 

 shaft a little further thau ou the edge. Ou the innermost primaries, again, it is very 

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

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

 mantle. The secoudaries are mostly purs white, but toward their euds have a space 

 grayish-blue of about equal extent ou 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 viuder tail-coverts 

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

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

 nearly pure white. The external imir, 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. 



Ubneiisionis. — 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 at 

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

 2.10 ; tibia} bare, 0.50 ; tarsus, 0.80 to 0.85 ; middle toe 0.75, its claw 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. 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.G6 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. 



Young-of-the-ytar in Juf/itst. — 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 .'u tinge of reddish. Forehead grayish-white ; ou the vertex 

 this gray is intermixed with lafge, roundish, illy-defined spots of blackish; ou the 

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

 only being gray. Ou the sides of the head, as far as the eyes, the black is also nearly 

 pure. The ground color of tlu; 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 

 couspicuous, and give i)erhaps the predominating color to the upper parts; bul they 

 are not so distiuctly defined, nor so dark, as in vxtcnira. The lesser wiug-coverts along 

 the edge of the fore-arm form a continuous band of nearly i)ure brownish-black. The 

 lesser and median coverts are conspicuously tipped with yellowish-gray. The greater 

 secoudaries, however, fade into nearly pure white at tlieir tips. The .secondaries are 

 white, with the outer web, excejjt at tip, and the median portion of the inner web, 

 dark ])lumbeous or ashy-gray. The primaries are colored almost exactly as in tho 

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

 the emargiualion being but little more than an inch. T\w inner webs of all the rec- 

 trices are nearly jiure while, but the outer webs are i)lumbe(>us-gray, inerea ing iu 

 intensity from within ontwaid ; so that the outer j)air of recti ices, which an; but 

 little tapering or elongatc-d, liavc^ their outer w^^bs grayish-black, deepest toward 

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

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



I have never seen the adult winter i)lumage of this species, and am therefore unable 



* 1 have seen a single undoubted specimen (»f this species which had tho outer wob 

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

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



