706 HYDROCHELIDON LARIFORMIS, BLACK TERN. 



the sides of the head below the eyes and ear-coverts, the chin, throat, neck all ronnd, 

 and the whole nnder parts, jjxre while. The under wing-coverts retain a good deal ot 

 their ]dnnilieous hue. The ujjper parts generally, and especially tiie ])riniarios, are 

 uiucb as in summer; but the tint of the pliuulieous, especially on the rump, is consid- 

 erably lighter, and the i'eathers have faint whitish margins. The back between the 

 shoulders is considerably lighter than in summer, but a little darker than the rump. 

 Along the fore-arm, just beyond the whitish edge of the wi)]g, there is a rather broad 

 baud of grayish-black, formed by several rows of the lesser coverts. Along the dorsal 

 aspect of the arm, also, there is something of this black band, but the color is con- 

 cealed by the scapular feathers. The secondaiies are considerably darker than iu 

 summer, being iu this respect fully equal to the ])rimaries ; and the comparative shades 

 of their inner and outer webs are exactly as in the i)rimaries. On the crown the white 

 of the forehead becomes obscured and variegated with blackish or grayish-plumbeous, 

 which grows darker on the nape, and on the sides of the head sends forward a band 

 througli the eye, to become intensitied into a blacker spot just anterior to it. The 

 feet are brownish-black, with little or no reddish ; the bill pure black. The rhachides 

 of the i)rimaries are darker than in summer. There is no appreciable difl'erence in the 

 eniargiiiatioii of the tail, nor in the shai)e of its individual feathers. 



IVIiile duntgb)(), in Jiiguist. (hiring the iiividf, the adults are in a peculiar state of 

 plumage. The entire uuder parts (except the inferior caudal tectrices), and the head 

 and reck all round, are remarkably variegated with pure white and pure black. The 

 relative amounts of the two colors varies with almost every specimen, dejiendiug of 

 couise upon the particular stage arrived at. In general, the forehead and throat, as 

 far as the breast, become lirst pretty uninterruptedly white. The crown, occiput, and 

 nape are then equally variegated with the two colors, in small spots and lines; but the 

 auriculars, and a spot jnst before the eye, are usually pretty purely black. The should- 

 ers and edges of the wings show traces of the giayish-black that is to appear. The 

 now old and worn-out primaries have lost most of their silvery hoariness, and the 

 shafts are nearly pure yellowish-white, except at their extreme ajiices. The bird iu 

 other respects is generally as in summer. 



YoniKj-of-the-yenr in zlufjutit. — The .size is less thau that of the adults; the bill is 

 smaller, weaker, softer, without very sharply defiued angles or ridges. The emargina- 

 tiou of the tail is very slight, being only about half an inch, and the lateral rectrices 

 want even the slight elongation and tapering which those of the adults have, being 

 broad to their very apices, which are somewhat oblique truncated. There is an inde- 

 scribable softness and general mollipilose condition to the plumage, readily recogniz- 

 able, both by sight and touch, to the expert in such matters. 



Bill brownish-black, the base of the lower mandible dull, dirty flesh-color, the 

 inside of the mouth yellow. Legs and feet light brown. Forehead grayish-white, 

 this color exteuding over the eyes as such, but deepening on The crown and occiput; 

 into grayish-brown. This color extends over the nape down to the back, and there 

 obscures the general plumbeous hue of the parts. On the middle of the back, between 

 the shoulders, this brown is quite uniform ; on other parts it merely forms tips and 

 margins for the feathers, including the superior alar and caudal tectrices, and the ter- 

 tials and scapulars. The row of least upper wing-coverts is grayish-black, as in the 

 adults iu winter. The tertials have also whitish tips, in addition to their subterminal 

 brown ones. Before the eye is a crescent of deep, pure black; behind the eye a patch 

 of pure black extends over the auriculars and a little distance on the sides of the neck. 

 The under parts are pure white ; on each side of the breast there is a large spot of 

 l)lnmbeous-browu, which, however, does not meet its fellow of the opposite side. The 

 sides under the wings are very light plumbeous, much the same hue as the inferior alar 

 tectrices and axillary feathers. The secondaries are like those of the adults iu winter; 

 the primaries like those of the full-plumagcd summer birds, oi;ly that their shafts a.ro 

 sui)erioily brown, not white. 



Dimensions of the adult. — Bill above, 1.10; along commissure, l.fiO; from feathers on 

 side of lower maudiljle, 1.08; gonys, O.GO; height at base, 0.iJ5 ; length, 9.25 ; extent 

 of wings, 24 to 25; wing froui carpus, 8.25; tail, :5.75; depth of forking, 0.90; tarsus, 

 0.08; middle toe and claw, 0.90; tibiiie bare, 0.40. 



Dimensions of llu- yonnd-of-the-year. — Bill above, 0.95 to 1 ; depth at base, 0.20; from 

 feathers on side of lower mandible, 0.95 ; gonys, 45 ; tarsus, O.OO ; middle too and claw, 

 •0.85; length, 7.75 to 8; extent of wings, 23.50 to 24 ; tail, 3; depth of emargination, 0.50. 



Anaioyniifil eharaciers. — The mouth is narrow, its sides concave, and its tip attenu- 

 ated, beyond that of any other species. The palate is soft and vascular to within half 

 an inch of the tip. The median palatal ridge .commences far foiward ; it is narrow, 

 but prominent, its edges posteriorly, and the edges of the nasal aperture, slightly i)apil- 

 late. The sulcus between it and the lateral ridge is well marked and deep. The lateral 

 ridges arc; short and sinuate, extending no farther back than the median. The poste- 

 rior vaulted space small but well arched, the nasal slit exteuding far into it. Posterior 

 fringe of oblique papilhe well developed. Tongue exceedingly acute, narrow, longi- 

 tudinally grooved along the dorsum, anteriorly corneous, its apex bilid, its xjosterior 



